first published in autumn 2006 last
updated 12/10/24
Wespe-Class Armoured
Gunboat: The Model
Introductory
Note
Work on this model began in autumn 2006 and then progress with
various long interruption for personal reasons and due to
diversions, such as the construction of tools and machnies
described elsewhere on this Web-site. While you will find below a step-by-step description of
building the model as it progresses,
this is not a continuous 'blog', so watch out for the date on
the beginning of paragraphs to identify new material. For ease
of reference the following table allows to jump to the various sub-sections.
The scale chosen for the
model is 1/160, which admittedly is somewhat unusual for a ship
model. However, the reasoning behind this choice was that a
large selection of N-scale railway figures is available that
eventually will crew the ship. There are also space and
portability consideration, which are important for someone, who
has to move from time to time for professional reasons.
The model will be a waterline model. This will
allow a dioramic presentation of the finished model. Besides,
the hull below the waterline is not quite so graceful. Above
the waterline the hull is also more or less prismatic, with
vertical bulwarks and virtually no sheer. These parameters
together call for a bread-and-butter construction.
The building
drawings are a combination of re-drawn Admiralty plans and scans
thereof. These are printed to scale on the laser printer and the
print-outs glued on top of e.g. the MDF board to serve as a
guidance for cutting and sanding.
Materials
Choice of materials
I had been contemplating a variety of materials for
the hull; for instance Plexiglas®
layers with bulwarks made from brass foil. In the end, I
choose MDF (medium-density fibre) board, which is available in
thicknesses down to 1 mm from architectural model supply
houses. Other parts will be constructed from or covered
with Bristol board, which is also available in various
thicknesses (or rather weights per square metre). The bulwarks
etc.. will be made from Pertinax®
(phenolic resin impregnated paper, FR-2), which is
available in thickness's down to 0.1 mm. Bristol board
and then Pertinax® are easily cut with a scalpel, a razor blade or
scissors and will not crease or dent as metal foil might. I currently have no facilities for photo-etching
large parts, but if I had, perhaps I would have made the
bulwarks from brass still. The other advantage is that
Bristol board can be readily and permanently glued using
white glue. Bonds between large areas of metal foil and Plexiglas® might become detached, though the plating on the steam-tug,
made from copper foil, has lasted now for nearly twenty
years. Pertinax® can be glued using
cyano-acrylate or epoxy-resins. The dinghy of the steam-tug
had received planking made from Pertinax®
and glued with cyano-acrylate glue.
While I have been shying away from thermoplastics,
such as polystyrene, on account of it being suspicious to be
not 'permanent' (e.g. the articles
by
Dana Wegner), practical experience shows that plastic
models built over 35 years are still intact. So I may
reconsider my position in this respect. Polystyrene, of
course, has several advantageous properties.
Some thoughts on Etched
Parts
Some people refer to the process of making
photo-etched parts as chemical milling and that is the way I
view it; a process to cut out and shape parts that are too
small or otherwise to delicate to handle conveniently with
other manufacturing processes. Unfortunately, the employment
of this process moves much of the modelling work onto the
computer, as the patterns or masks now are produced with the
help of a drafting program. These masks are largely developed
by scaling the contemporary drawings and drawing the
respective part over it in a different layer. These parts are
then composed into the actual mask. Of course, 'left' and
'right' sides have to be drawn separately, if the part is to
receive surface-etched detail. A strict procedure of copying
and mirroring has to be adhered to in order to achieve a
perfect line-up. Much thinking has to go into the best shape
of parts and some experimentation. The etching process is not
so well controllable, as a machine tool, at least in the
simple set-up I am using. The best thickness of interlocking
slots or the drawing size to achieve cut-outs of a specific
dimension and similar features have to be found by trial and
errors sometimes. Literary it is often 'back to the drawing
board'.
This set-up is only suitable for dip-etching.
Commercial companies use foam or spray etching, which work
faster and produce less undercut. I decided to work with very
small 'frets' only, the size of one or two large stamps. This
reduces the cost of material, if something goes wrong and the
smaller size seems to make it easier to get uniform results
over the whole 'fret'. I bought second hand a UV-source for
exposing printed circuit board. It has a timer and hence makes
the process more repeatable. The developing and etching
vessels are plastic film tins, coming from the standard film
rolls (don't get any new ones since I have switched to
digital, of course). The brass is bought in a ready-sensitised
state, so no messing about with UV-sensitive lacquer is
needed. Much experimentation went into a suitable way of
making the masks. Eventually a newly bought ink-jet printer
produced sufficiently uniform print-outs on overhead foil, but
the resulting masks are not really perfect. However, I did not
want to go a commercial photo lithography company for them.
The hull and
superstructures
Autumn 2006 - The
basic bread-and-butter construction of the hull is shown in
the pictures above.
The Barbette mainly consists of a semi-circular breastwork
armour, backed by hardwood and by an open space covered with
thin plate. The latter presumably to retain splintering wood
in case of an impact. Since no tube of suitable dimensions for
the breastwork was to hand, I made a short laminated one from
Bristol board glued together with white glue. The edges were
soaked in thinned white glue before being trimmed down on the
lathe. The tube then was varnished with filler for wood before the edges
were sanded. Finally a half-circle was cut from the tube on
the jig-saw. More wood-filler was applied before final
sanding. After cutting in half it was glued into place. The
inside of the barbette was lined with hard-paper to give a
smooth finish.
The fore-deck has been covered in a sheet of thin Bristol
board and the camber of the wooden decking built up with an
additional piece of board and putty (I am using fast drying
bodywork putty from car repair suppliers). The anchor pockets
have also been lined with thin Bristol board, but Pertinax
would have been better for this.
All surfaces that would have been iron plating, will be
covered in thin sheets of Pertinax. The necessary holes for
portholes and other opening will be drilled or cut before the
sheets are fixed. In this way the barbette was lined with sheets
of Pertinax,
as was
the deck-house.
Cutting the layers on a
powered fretsaw
Sanding the
sides of each layer vertical on an improvised disc
sander
The first
layers
The barbette
and pockets for the anchors cut out
Milling
slots for the rubbing strakes
Improvised
drum
sander to work the inside of the barbette
Shaping
the body on the new shop-made disc sander
Tube
made from laminated Bristol board
Trimming
tube
on the lathe
Drilling the hawse pipe
on the horizontal milling machine
Deckhouse partially
clad in Pertinax
January 2017
Most of the decks were plated and this plating
was covered in oil-paint that was mixed with sand and cement
in order to provide a certain corrosion resistance and above
all a better grip in wet conditions. A modelling
plan drawn by Wolfgang Bohlayer shows wood on some
decks, but evidence that since has become available shows that
this was not the case.
Linoleum decking
apparently was never used on these boats. However, as the model
will show the boat in its original appearence, the plating was
reproduced by engraving fine lines into then sheets of Pertinax.
All decks, including that of the barbette will covered in this
way. The exception is the deck above the foc'sle that a cover in
planks, presumably to reduce wear, where the anchors were
worked. This planking was laid-out in a radiant pattern, which
seems to have been more resistant to the gun-blast than the more
common parallel layout. The planks were also reproduced by
lightly engraving the plank seams. In reality these seams would
have been more or less flush with the deck, depending on the
temperature and humidity, but a light engraving adds some life
to the appearance.
Progress in
constructing the hull
Engraving
plating and planking
Excerpts
from contemporary drawings
Barbette
Toner-trasnfer printing of
bulwark layout
The
barbette - The floor of the barhette is partially covered
in planking, presumably to protect the armour-steel deck
underneath from the damage that might occur, when the heavy
shells are handled. The steel deck underneath and in front of
the barbette armour-belt is slightly sloping to deflect incoming
enemy-shells from the ammunition storage-rooms. Within the
barbette this is filled with timber to make a level floor. The
interpretation of the various items that can be seen in the
contemporary drawings is not straightforward. However, one can
see a hatch that gives access to the crew's quarters (where also
the hand-cranks for turning the gun-carriage is located). Then
there is a round hatch for hoisting up the charges from the
powder-locker below and a square hatch for hoisting up the
shells. From the drawings it appears that these hatches were
covered in steel-gratings. There is a further hatch with a
double-lid that, according to a hand-written notice on one drawing
is a man-hole leading
to the ante-room of the shell-locker. However, as it is not
drawn in the cross-sections we do not know its height. There are
also a couple of racks for shells and some other rack-like
features, the purpose of which I do not know - perhaps for tools
needed in handling the shells. Unfortunately, there are no
photographic images that show the rear of the barbette.
Stairs leads down from the bridge into the barbette. In addition
two ladders allow quick access from the deck.
The
floor of the barbette, which apparently did not have any camber,
was built up from two layers of Pertinax one representing the
steel-plating and engraved accordingly, the second cut out and
engraved to represent the wooden flooring. The construction of
the various hatches is described below.
Bulwarks,
hull- and deck-plating installed
Making
and installing the hawse-pipes
Scraper
for half-round profiles
Rails and
rubbing strakes installed
Toilet evacuation pipes
Milling the steps of
jacobs-ladders
May 2019
- The main-deck plating, which had already been prepared a long
time ago from a piece of bakelite (see above). The holes for the
various fittings where marked out over a drawing and then
drilled. The translucent property of the bakelite is very
helpful for marking out. Once glued on, the deck was carefully
sanded to the contour of the hull.
I spent a lot of time deliberating the best way to make the
plating of the hull and the bulwark. The shape is quite simple,
as the sides are vertical from just below the waterline
(probably to facilitate the production of the armour plating
that needed to be curved in only one direction). The original
idea was to cut the plating in one piece from brass shim stock.
This would have resulted in near scale thickness of the bulwark
plating. I considered this too flimsy, even if the handrail was
soldered on. Another option would have been to use 0.13 mm
styrene sheet. Again I considered it too soft. Bakelite sheet of
0.1 mm thickness would have been closer to scale, but rather
brittle. For practical reasons I decided to use 0.2 mm bakelite
sheet.
The layout of the freeing ports, the location of stanchions, the
ash chutes, toilet drain pipes, and port-holes were drawn onto
an expansion of the bulwark that was developed from the original
drawings. The drawing then was laser-printed onto an overhead
projection foil (remeber these ?). This foil was taped to a
piece of bakelite sheet and the drawing ironed onto it, using
what is called the toner-transfer method.
The plating was cemented to the MDF hull using cyanoacrylate
glue (CA). I am not very fond of CA glue, but it forms secure
bonds with bakelite. On the prototype, the
bulwark plating was attached to the hull by an angle iron (8
cm x 8 cm) running along the top of the hull. I simulated the
vertical part with a 0.5 mm wide strip of self-adhesive
aluminium sheet into which a row of rivets had been embossed.
The horizontal part would disappear under a thick layer of
tar-based paint that was mixed with sand and onto which sand
was dusted to provide a non-slip deck.
The hawse pipes were made from
some 2 mm x 0.5 mm brass tube. First the angle with the hull
was cut and then an oval ring from 0.4 mm copper wire was
soldered onto this surface. The part was then taken into a
collet on the watchmakers lathe and drilled out to 1.7 mm ID.
Finally, the funnel shape was formed with diamond burrs and
polished with silicone burrs. The hawse-pioe then was cemented
in place and the end above the deck ground down in situ flush with
the deck. The cover on deck is an etched part I made already
several years ago. It was cemented on using CA and then
another funnel was shaped with diamond and silicone burrs.
Next step was to install at the bows the fairleads for mooring
cables etc. These were milled and filed from 0.8 mm thick sheet
of Plexiglas®.
Then the rails on the bulwark in the rear part of the ship were
installed. The rail also serves as a rubbing strake and
continues to the anchor-pocket at the bows. At first the bulwark
and rail (0.4 mm x 1.7 mm on the model) caused some
head-scratching and concerns for the stability of the
arrangement. I though about cutting a longitudinal slot into
some rectangular styrne, but finally decided to make it in two,
with the half glued inside and outside to the bulwark that have
been designed higher for the purpose. In this way a 0.4 mm x 0.7
mm styrene strip could be glued all the way to the outside of
the hull. A similar strip was glued to the inside. The
half-round profile was shaped using a scraper made from a piece
of razor-blade and held in pin-vice. The profile was shaped
after attaching it to the hull, because it was easier to clamp
the rectangular styrene strip while glueing. The glueing was
effected by infiltrating CA into the joint between the styrene
strip and the bakelite bulwark.
Arrangements varied somewhat between the different boats of the
WESPE-class, but there was a WC for the officers in the
deckshouse on the starbord side and a WC and pissoir for the men
and petty officers on the port side. Each had a half-round
evacuation pipe rivetted to the outside of the hull. The pipes
were protected against damage by a wooden fender. After a few
years of service, a strong wale/rubbing strake was added to the
boats that also widened to a kind of sponson at the stern to
protect the screws. However, this did not exist at the time in
which the model is represented.
Steps
ready to be installed
Jacob-ladders
Fairlead
for mooring hawser
Laser-cut lids
for the freeing-ports
Installation
of frames and lids
Laser-cut
doors
Decks-house and back of
the fore-deck with the doors installed
June 2019 -
There are two jacob-ladders on each side of the hull, a wider
one underneath the door in the bulwark and a narrower one a bit
forward. The steps probably were made from wood and had slots
towards the hull to prevent the water from collecting there and
to prevent the wood from rotting. The steps are made from 0.8 mm
thick Plexiglas® and the slots milled in. The sheet then was
sanded down to the width of the steps and the ends rounded. Then
individual steps of the right thickness were cut off on the
lathe set-up with a mini saw-table. Unfortunately, the steps
could only be cemented to the hull using cyanoacrylate glue,
there being no positive locking. A bit of cellotape provided a
guide for alignment. Nevertheless, the procedure was a bit
nerve-racking.
Further, fairleads for the aft mooring hawser were installed.
These were made from oval rings of copper-wire. The rings were
formed over two 1 mm-drills taped together, cut off and closed
by silver-soldering. The rings were sanded down to half their
thickness and one each of these rings cemented to the inside and
outside of the hull. The hole was drilled out and filed to
shape. February
2020 -Freeing
Ports - Originally
I had planned to surface-etch the lids and the frames on the
inside of the bulwark. The drawings for the masks were ready,
but I never got around to actually etch or have the parts
etched. Since I now have the laser-cutter, these parts were
cut from printer-paper (80 g/m2 = 0.1 mm thick). With a width
of the frames of only 0.5 mm, the surface-etched rivets may
not have come out anyway. The same for the rivets on the
hinges of the lids. At least not with my somewhat primitve
home-etching arrangement. If I had etched the parts from 0.1
mm nickel-brass, the overall thickness would have been reduced
to a more correct 0.05 mm (= 8 mm for the prototype) The lids have no latches to lock them and the
ports no bars across them to prevent items or people being
washed over board. This makes their construction simpler.
Papers, even the
smoothest ones, alway have a certain surface-roughness, at
least compared to the bakelite of the bulwark. Therefore,
the chosen paper was soaked in wood filler and spread to dry
on a thick glass-plate that was covered in cling-film. The
latter allowed to remove the paper without it rolling up.
The surface was then smoothed with very fine steel-wool. The
lids were cut from the thus prepared paper, but it needed
several trials to find the right cutting parameters in order
to arrive at parts of the correct dimensions. This is a
disadvantage of such simple laser-cutters and their
software. As the material is practically free, this is only
a nuisance, but no other loss. Also the etching may not work
out right in the first go, which may mean a considerable
loss of money and time, if the process had been outsourced-
Unfortunately, it does not work for very small parts with
the paper prepared as above. It turned out to better for the
very small parts, including the frames, to cut them from
unprepared paper. Perhaps I should switch to dark paper. Due
to its lower albedo (reflectivity) it absorbs more energy
from the laser. Unfortunately, all the coloured papers I
have come by so far are quite rough on the surface.
I cheated somewhat for the freeing-ports. As I was afraid
that I would not been able to cut them out cleanly and
evenly, I abstained from it. Also, the bakelite-paper used
for the bulwark for reasons of stability would have had a
scale-thickness of 64 mm, when looked on from the side.
Therefore, frames and lids were glued flat onto the inside
and outside of the bulwark respectively. I hope one will not
notice this too much, once the stanchions are in as well.
Frames and lids were glued on with zapon-lacquer. Little
laser-cut rectangles of 0.3 mm x 0.5 mm were stuck onto lids
to simulate the hinges.
Foredeck and decks-house were accessible through various
doors. These were cut from 0.1 mm bakelite paper with the
laser-cutter. The hinges were laser-cut from thin paper. In
both cases various tries were needed with different cutting
parameters and slightly altered drawings in order to arrive at
the correct size. Die parts were assembled using
zapon-lacquer. Zapon-lacquer was also used to glue the door
into place.
On historical photographs I noticed that each door had a
narrow step. These were represented by shaped and laser-cut
tiny strips of paper.
Once the door were in place the hole for the bullseyes were
drilled out. The laser-cut hole served as a guide. Once the
boat is painted, the glazing will be installed in form of
short lengths of 1 mm Plexiglas rods. The front of the rods
will be faced and polished carefully on the lathe.
At a later moment also the door-knobs will be turned from
brass and installed.
Best
available image of the bow scrollwork and name-plate
(S.M.S. SCORPION)
Only
available image of the stern scrollwork (S.M.S.
NATTER)
Artwork for the
bow scrollwork
Some
examples of (unused) laser-cut scrollwork and
the name-plates
Scrollwork and
name-plate in place
Stern
scrollwork in place
June 2020 - Scrollwork and
name-plates - As I had tried laser-engraving on
cardboard for the gun-layer stand, I wanted to try out this
technique also for the scrollwork and the name-plates.
Originally, I had foreseen to develop the scrollwork by
printing the design onto a decal-sheet and then build it up by
sculpting it over the printed lines with acrylic gel. The
name-plates could have been surface-etched in brass. One could
have etched, of course also the scrollwork in brass and then
complete it with acrylic gel.
It is not very clear what the scrollwork looked like when new
and from what material it was made. The fact that it seems to
have persisted intact over the whole life of these ships may
indicate that it was actually cast in some metal, rather than
carved in wood.
There are no close-up photographs of sufficient resolution in
the black-white-yellow paint-scheme. Closer photographs are
only available from a later period, when everything was
painted over in grey and some of scrollwork may have been
picked out in a darker grey. Originally it was probably
painted in yellow-ochre with parts of gilded. In any case,
available photographs are not clear enough to truly
reconstract the scrollwork, so some interpretation was
necessary.
In addition to the scrollwork per se, there was a shallow
sculpture of the animal after which the ship was named, for
SMS WESPE, of course, a wasp. Existing photographs only give a
vague idea what these sculptures really looked like. In any
case not for SMS WESPE.
There has also been some scrollwork at the stern, but
pictorial evidence for this is rather scarce. There is only
one known photograph that gives a full view of the stern of
this class of ships and this was taken at the very end of
their service life. Available copies of this photograph are
not clear enough to really discern what the scrollwork
actually looked like, so a fair amount of imagination is
needed to recreate it.
Creating the basic artwork for the decoration was a
multiple-step process. First a photograph of the respective
section of the model as built was taken in order to give the
necessary proportions. In the next step the best available
photograph with the least perspective distortions was chosen
and fitted over the model photograph. In another layer of the
graphics software (Graphic for iPad) the scrolls were drawn
free-hand (with the iPen) using the paintbrush-function and a
good amount of smoothing. This artwork was saved as a JPEG. On
the Internet I found a nice drawing of a wasp and turned this
into a pure b/w image with a good bit of editing in Photoshop.
Both, the scrollwork and the wasp were saved as transparent
GIF. In my favourite CAD-program (EazyDraw), the parts were
mounted together. This could have been done also in Photoshop,
but I did have a scaled drawing of the bow-section in EazyDraw
to which I exactly fitted the artwork. There were also some
addtional parts to be cut.
The scrollwork was cut/engraved with the laser-cutter using
the ‘half-tone’ function, which means that the laser is
modulated to emit less power when a grey pixel is encountered
and full power, when a black pixel is encountered. I had to
play in several iterations with the settings of the
laser-cutter in order to arrive at a satisfactory result.
In a first try the name-boards were made in the same way, but
the half-depth engraving around the letters resulted in a
somewhat fuzzy apearance of the letters. I, therefore, tried
out a different idea. From previous trials it was know that
the laser had no effect on transparent materials and very
limited effect on translucent materials. Hence, I covered some
cardboard with a thin layer of Pleximon 192 (essentially
liquid, light-hardening Plexiglas). A thorough curing this
sandwich was sanded flat and presented to the laser-cutter.
The laser removes all the cardboard, but leaves the acrylic
virtually untouched, with the exception of some light surface
roughness. One ends up with a piece of thin acrylic sheet to
which the letters and the scrollwork of the name-board are
attached. Within the limits of the resolution (0.05 mm) of the
laser-cutter the lettering turned out reasonably clear,
perhaps not as crisp, as when photoetched though.
The scrollwork elements were attached to the hull using
fast-drying varnish. The actual painting and guilding will be
done, once the hull has been painted.
The
aft part of a WESPE-Class-Boat (Lavverenz, 1900)
Etched
and soldered together stanchions (they are about 5.5
mm high)
The bulwark-stanchions in
place
Recessed
slide and anchor release gear
Recessed slide with
Inglefied-anchor put temporarily in place
View of
the bow with the anchor stowage
Plexiglas plugs
ready for insertion
Glazed portholes
Glazed portholes
December 2020 - bulwark stanchions - The bulwark in the
aft part of the hull is supported by a number of stanchions that
were cut from sheet metal and rivetted together. The looks for
these stanchions is reasonably well documented on a number of
photographs.
The stanchions I had drawn
already years ago and depicted the rivetting by
surface-etching. The material is 0.1 mm thick nickel silver.
They were made in double as mirror images and soft-soldered
together in pairs with soldering paste so that the rivetting
appears on both sides. The location of the stanchions
was marked on the bulwark before this was put into place by
thermo-transfer of a drawing, i.e. a laserprinter printout was
ironed on. The stanchions were cemented in place with
fast-dryining varnish.
Already a short while ago I had fashioned
the boiler-ash chutes by milling to shape little blocks of
acrylic glass. They were cemented to the bulwark inside and
outside at this stage too. January
2021 - Anchor stowage and release gear - The
Inglefield-anchors are stored on sort of recessed slides and
released by a traditional form of gear. This gear consists of a
rotatable iron bar with a couple of thumbs welded on over which
the securing chains are hooked. The chains go around the anchor
and the other end is shackled to the wall of the recess. The bar
is prevented from rotating by lever that is also welded to it.
The lever in turn is locked by a rotating claw at the end of a
second lever. I suspected this mechanism from the available
drawings, but wasn’t shure about it – a German colleague had
better eyes than me an could confirm this indeed on the not very
clear photographs.
The slide is protected by three T-rails on each from the weight
of the heavy anchors.
The release gear was fabricated from 0.3 mm diameter tinned
copper wire and assembled using varnish. The rails in turn are
fabricated from laser-cut strips of Canson-paper that was soaked
in varnish. They also function as bearing for the bar of the
release gear. I suspect the bearings were a bit more elaborate
on the prototype, but I don’t have more detailed information.
The locking claw is also a microscopic laser-cut piece. As
usual, I had to experiment with different variants of the
drawings and settings of the laser-cutter until I managed to
produce reasonably clean parts. December 2021 - Porthole Glazing - Following the
discussion on ways to make the porthole glazing further up, I
looked over all available photographs and came to the conclusion
that one does not actually seem to see the bronze frame from the
outside. On the other hand, most photographs or their scans do
not have sufficient resolution to really see such detail.
In order to make my life simpler, I decided to go for solid
Plexiglas plugs. I did have 1 mm Plexiglas rod in stock and
short sections were cut from this to make 2 mm long plugs. The
plugs have to be a bit longer than their diameter, so that they
can be inserted straight. The front face was turned flat on the
lathe and the back-end was given a bit of a chamfer for easy
entry into the pre-drilled holes after which it was painted
black using a black permanent marker pen. The pieces were then
transferred to the micro-mill for polishing the front face with
a silicon rubber polishing bit.
In order ensure that the porthole plugs are set at equal depth,
a little ‘tool’ was made, a punch with a recess of 0.3 mm depth
around the rim.
The 30.5 cm Rk/l22 gun
Lower Carriage
February 2007 -
There are some fixtures for the gun that need to go into their
place in the barbette early during the construction, including
the races for the gun carriage and the semi-circular toothed
rack that is part of the gun-training machinery. I decided to
make these from steel, even though ferrous metals in model
construction are frowned upon by museums. My justifications were
that it is difficult to represent cast iron or steel by paint
and that there hundreds of models in museums around the world
that contain iron. I have used steel it in models some twenty
years ago and presumably due to the lacquering shows no signs of
rust.
Cutting thin disks from round stock of sizeable diameter is a
pain I wanted to avoid. Against my better knowledge I picked a
suitably sized steel washer as starting material. Unfortunately,
the steel used does not cut very well at all and lot effort was
spent to avoid chatter marks while turning and to obtain a
reasonably good finish. The various types of wheel collets
available for the watchmaking lathe come into good use for
working on inside and outside diameters of the disks.
I set up the
hand-shaper for cutting the rack teeth, but had to throw away
the first two attempts because of the poor material and because
- again against better knowledge - I did not lock the traverse
slide when cutting. The table was removed from the shaper and
the home-made dividing head bolted on instead. For lack of a
proper tool grinder (another project) I hand-ground a cutter for
the rack tooth (0.1 mm at the bottom) from a rod of high-speed
steel. For holding this tool-bit in the shaper, the old
lantern-style tool holder from the watch lathe came very handy.
The unwanted parts of the ring were cut away on the shaper using
ordinary left and right hand lathe tools. Finally the necessary
sections were trimmed off with a fine saw blade on the lathe's
sawing table.
Roughing out the metal
disk with the backing of a wooden disk
Grooving the
races with a specially ground bit
Cutting out
the inside of the large, backward ring
Trimming the
outside of the small, forward ring
Shaper
set-up
for cutting the toothed rack
Cutting
the
toothed rack with a specially ground tool
Cutting
away
the unwanted part of the ring with an ordinary
tool
The
set-up showing the finished rack
The
races and the toothed rack ready to be trimmed
to correct length of arc
Base-plate
and rails for upper carriage laser-cut from
Canson-paper
The
basic frame of the lower carriage from the
rear
February 2020 - The
lower carriage of the gun was a rather complex construction
from rolled L-profiles and thick steel sheet. Unfortunately
only the drawings in GALSTER (1885) and the coloured synoptic
drawing from the Admiralty have come to us. Many construction
details are superimposed onto each other with dashed lines, so
that the interpretation of the drawings is rather difficult in
places. As aids to interpretation with have one close-up
photograph, the large demonstration model in the navy museum
in Copenhagen, and the preserved guns of Suomenlinna Fortress
off Helsinki. The carriage for the Danish iron-clad HELGOLAND,
however, differs from that of SMS WESPE in some details, being
actually a turret-carriage. The carriages in Suomenlinna are
Russian copies of Krupp fortress carriages, but they allow to
verify certain construction details that are not clear from
the drawings.
Originally I had planned to construct the lower carriage,
like the upper carriage, from surface-etched brass parts. To
this end I produced some time ago already the needed detail
drawings. Surface etching is a very good process to simulate
rivetting. In the meantime, however, I had purchased the
laser-cutter, so that laser-cut parts would be an alternative. I
had hoped to cut the parts from bakelite paper. Various trials
with different cutting parameters unfortunately were not very
successfull for the intricate parts. The 5 W laser ist too weak
to burn the material fast enough. Burrs of molten and partially
carbonised resin form. Therefore, I fell back onto Canson-paper,
which is a bit over scale with its thickness of 0.15 mm.
The
drawings for the etching masks had to be reworked for laser
cutting. It turned out during assembly that I had made several
mistakes or misinterpretations. If I had send them off for
etching this would have been costly, as both masks and etching
would have to be redone. When cutting paper with a laser such
corrections can be made quickly and easily – and the material
costs practically nothing.
The laser-cut parts were soaked in nitrocellulose wood-filler
and once dry rubbed with very fine steel wool. To double up
parts and for assembly zapon lacquer was used. This dries so
fast that no special arrangements for fixing the parts are
needed.
I did not take pictures of the different steps of assembly, as
this would have rather impeded the process. First all parts to
be doubled up were cemented together using zapon lacquer and
weighed down to keep them flat during drying. The longitudinal
parts of the carriage had slots cut into them, so that the
transveral parts could be positioned exactly. The frame assembly
then was cemented to the base plate (which in reality was not a
plate, but rather the frame was put together from L-profiles and
steel sheets). The racers, again in one piece, where glued on
top of this assembly. Underneath the base plate the housing for
the training gears (which will be very much simplified as they
will be barely visible upon completion of the model).
One can see on the laser-cut parts marks for the rivets. These
will be added as tiny spots of white glue. More details will be
added in the next steps, but have not all been drawn yet.
The basic
frame of the lower carriage from the rear
The basic frame
of the lower carriage from underneath with the
housing for the training gears
The
basis frame of the lower carriage with the upper
carriage and the gun put temporarily in place
Working
drawing for the parts of the hydraulic brake
The
individual parts of the hydraulic recoil-brake
Dry-fitting of the recoil-brake into
the lower carriage frame
Buffer
beams on the lower carriage
One buffer dry-mounted
March 2020 - The 30.5 cm
gun in pivot-carriage C/76 was one of the first guns in the
Imperial German Navy that was fitted with a hydraulic
recoil-brake, at a time, when compressors and brooks were still
the standard.
The recoil-brake consists of a long cylinder with
screwed-on cylinder-covers at both ends. The covers are pierced
for piston rods and are sealed with packed glands. The piston
rods are fixed at the front and rear end of the carriage
respectivly. The piston is designed as self-opening one-way
valve. The cylinder is filled with glycerine through a valve on
top. The front-end cylinder covers acts also as cross-head and
the upper carriage is linked up through two short forked
connecting rods. The cross-head runs on a kind of slide to
support the weight of the brake. The two piston-rods are only
connected by the short piston, which also acts as valve, and
that would not be able to support the weight.
When the gun is fired, the upper carriage slides back and the
piston is pushed through the glycerine, converting the kinetic
energy of the recoil into heat. The valve in the piston prevents
the upper carriage from sliding back into firing position. In
order to bring the gun forward, the rear end of the carriage is
raised by turning the excentric bearings of the rear wheels and
opening the valve in the piston. To facilitate this, the rear
piston rod is hollow and a spring-loaded valve-rod extends
beyond the piston-rod. The valve rod can be srcewed in and out
by the aiming gunner using a long lever. In this way he can let
the gun roll back into the firing position in a controlled way.
Unfortunately, not much of the hydraulic brake will be visible
on the finished model, so that it was reproduced in a somewhat
simplified way. It consists of five parts.
The piston rods were fashioned from clothes pins of 0.6 mm and
0.7 mm diameter respectively. Clothes pins are very suitable for
piston rods, as they have a nicely polished surface. The eye of
front piston rod was milled/filed from the head of the clothes
pin.
The cylinder was turned in one piece together with the covers
from a short length of 2.5 mm round steel. On the micro-mill a
hole was cross-drilled for another short piece of steel that had
the cross-head pins turned on. This piece was soft-soldered into
the cylinder cover. The packed gland is compressed by a
hexagonal nut, for which the hexagon was milled on in the
dividing head in the same set-up.
The forked connecting links were laser-cut from paper and
consist of three pieces each. The bronze
housing for the valve spring was turned from 1 mm brass rod. The valve lever will be added at a later
point.
Buffers and
fastening nuts
Buffers and
fastening nuts – the buffer have a diameter of 1
mm
Safety
claw, pivot plate and drive shaft
Milling the loading
crane
Fork for pulley
Milling
the pinion and cog-wheel for the winding
mechanisms
Part-assembled
loading crane
Buffer beams - In
order to limit the recoil and the running out of the gun,
buffer beams are installed at both ends of the frame of the
lower carriage. Each beam carries four buffers against which
the front cross-beam of the upper carriage runs. The buffers
are designed as pistons with piston rods screwed to the back
of the beam. It is not completely clear what the elastic
elements were. The drawings seem to indicate rubber discs with
metal separating discs. On some of the guns at Suomenlinna
fortress there are remains of rubber discs, while the
demonstration model of the Danish navy seems to have spiral
springs.
The bodies of the buffers were turned from 1 mm soft steel
wire. The spring element was simulated by winding around it
several turns of 0.15 mm tinned copper wire. Whether this is
meant to meant to represent rubber discs or springs I will
decide, when it comes to the painting stage.
The nuts that keep the buffers to the beam were also turned
from 1 mm soft steel wire. First, the hexagon for a 0.6 mm
spanner width was milled on in the dividing head of the
micro-mill. On the lathe a 0.4 mm hole was drilled and 0.3 mm
long nuts parted off. And no, I didn’t cut a 0.4 mm thread.
The parts of the buffer beams were laser-cut from 0.15 mm
thick Canson paper and soaked in wood-sealer. They were folded
and assembled using zapon varnish. In order to make folding
more precise, a row of tiny holes were ‘punched’ along the
folding lines with the laser-cutter, which weakens the
material there. The rivetting was simulated by tiny drops of
acrylic gel that was applied with a syringe and a fine
injection needle. The needle was ground flat at the end for
this purpose. Safety claws - A heavy forged claw at each end of the
frame hooks under the rail on which the carriage trucks run to
prevent the carriage from lifting off the pivot. The profile
of the hooks was taken off the original drawings and cut in
multiple copies from Canson paper. These were glued together
as a stack and sanded smooth – not a 100% satisfying solution,
but filing such tiny but wide claws from the solid I found too
fiddly. The lugs that attach the claws to the frame were also
cut from Canson paper.
The gun is trained with the aid of a curved rack, a
crown-wheel segment in fact. In to this rack made from bronze,
a steel pinion engages that is driven by a shaft from a sort
differential, which is powered by man-power from the deck
below the barbette. After some consideration I decided not to
make the pinion, though I would have liked the challenge,
because it will not be visible once the gun has been installed
on board. The driving shaft, which also is barely visible was
fashioned in a simplified was from a clothes pin, the head of
which was turned to shape. May 2020 -
Loading crane - Mechanically, the loading crane is
a relatively simple affair, a rope winding drum driven
through a pinion and cog-wheel, powered by a hand-crank,
and for turning a worm-wheel drive equally powerd by a
hand-crank. The console on which the crane rests is a
quite complex part that was bolted together from several
cast parts. My first thought was to mill the console
from the solid or rather to solder it together from
several milled parts. I finally decided to put the
laser-cutter to work and fabricate it from several
cardboard pieces. On the bottom line, this was the
easiest solution and compatible with the rest of the
under-carriage
The crane on the demonstration model in Copenhagen
mainly consists of bright pieces of steel or cast-iron.
Whether this was the case too originally on the
prototype cannot be verified anymore, as no detail
photographs exist. It is perhaps doubtful due to the
continuous maintenance required to keep rust at bay.
Although, the navy was not concerned about camouflage at
that time, they were aware of the risk of early
detection by the enemy due to bright metal part
reflecting the sun. However, I allowed myself the
artisanal-aesthetic license of bright metal, as I think
it will be a nice contrast to the dark green of the gun
carriage later.
The actual crane was milled from a 2.5 mm steel rod. To
this end the thickness profiles in both dimensions were
taken off the original drawings and ‚stretched’ out
straight in the CAD software. After milling, the part
was softened in the flame, so that it could be bent
according to the drawing. The hole and slot for the
pulley were machined afterwards, as the part could break
there during bending. The final shaping was done with
silicone-bound grinding bits.
Pulleys and forks form them are tiny
parts machined on the lathe and the milling machine.
The mechanism of the crane consists of a good dozen of
lathe-turned parts, that were, apart from their minute
size, were not particularly challenging.
The cog-wheel, the pinion, and the worm-wheel were
turned together with their axes in one piece. On the
photographs I counted 60 teeth on the large wheel,
which gives, together with a diameter of 3 mm a module
of 0.05. Making a single tooth mill seem to be too
much work, so that I took the short-cut of just
gashing the wheels with a 0.1 mm thick circular saw.
It is only about the look and I did not intend to make
these gears functional. Hobbing a worm-wheel of just 1
mm diameter was too big of a challenge, but at least I
tilted the axis 20° when gashing it. The
final assembly can only be done, once the
crane-console has been attached to the carriage and
the whole thing is painted.
Drawing for laser-cutting -
gun-layer stand
First Version
with engraved surfaces of the platform for the
gun-layer
Final
Version of the platform for the gun-layer
Tea-bag fabric
The collection of
gratings and steps
Caster
wheels prepared for assembly
Caster
wheels in place
May 2020 - Gun operating platforms and gratings - The gun
is mounted effectively on a turntable, so that platforms for crew
are needed to give them access to the gun, while is being trained
left or right. These platforms are made of wire gratings that are
placed into angle-iron frames. The frames are suspended from the
lower carriage by brackets. The pictorial evidence (photographs,
drawings) is not detailed enough to fully understand what the
brackets actually looked like and how and where exactly they were
attached to the lower carriage frame. Some additional information
is given by the Danish instruction model and the Russian clones in
Suomenlinna fortress, but the carriages of these guns differ in
detail from that on SMS WESPE. So the reconstruction of these
platforms remains somewhat conjectural.
There are 13 gratings and steps in total, plus the platform for
the gun-layer. The original plan was to photo-etch the frames from
brass sheet, but with the arrival of the laser-cutter I changed
this plan. The drawings were modified accordingly. The obvious
solution to simulate the angle-iron frame was to design an open
frame and then fold-up the vertical parts of the angle. However,
it proved impossible to fold the narrow, 0.3 to 0.4 mm strips
consistently and without distortions. Not sure this would have
worked with the PE parts either. It was then decided to make the
open frame and the vertical parts separately as narrow strips and
glue them together with lacquer. After several iterations of
drawings and laser-cutter settings to arrive a workable width of
the strips etc. I arrived at an acceptable solution, albeit the
‘angle-irons’ are somewhat over-scale.
Assembly was a slow and nerve-wracking process. I did not manage
to do more than one grating per evening and it involved a lot of
(mental) foul language. Eventually, I got them all together.
Zapon-varnish was used throughout the assembly. The finished parts
are surprisingly strong
The original plan was to simulate the wire-mesh of the gratings by
real wire-mesh and I obtained from wires.co.uk some really fine
mesh in brass and steel. The idea was to pull every second wire in
one direction, as the original mesh was rectangular. It proved,
however, very difficult to cut such small pieces (sometimes only
1.5 mm wide) from the wire-mesh. Then a present to wife in form of
a box with various (fruit) teas came to my rescue: some of the
teas came in bags made from extremely fine but lightly woven
fabric. I do not know what material it is, but as it dissolves in
acetone, it is probably cellulose acetate silk or Rayon. Such
fabrics are also used in silk-screen printing and I had not
chanced upon the tea-bags, I would have looked there. This
silk-screen or fabric can be precisely and easily cut with a new
scalpel blade. The small pieces of fabric were dropped into the
frames and fixed at the edges with a light touch of varnish.
The platform for the gun-layer is a more complex structure. A 5 mm
sheet-metal armour shield is meant to protect him from shrapnel
and small-arms fire. The armour shield is reinforced at the edges
with rivetted-on metal strips. The original plan was to produce
this as a surface-etched part. I realised that the laser-cutter
interprets half-tone images as instructions to modulate the laser
power so that it does not cut all the way through. Laser-engraving
in other words. It did produce the desired effect, albeit with the
engraved surface being rather rough due to the digitising effect.
However, this part then was so thin and flimsy, that it would not
stay in shape, when attempting to shape the round corner. I
reluctantly accepted that it would be somewhat over-scale in
thickness and cut the armour shield and the reinforcing strips
separately. They were glued on top of each other with varnish and
then the round of the shield formed over a rod. Folding and gluing
completed the process.
I am not entirely happy with the result and tend to think, that
etched parts may have looked finer. But then their assembly would
have required a lot of very delicate soldering work – I don’t
trust CA for metal/metal bonds too much. On the other hand,
attaching the gratings to the lower carriage frame is likely to be
easier for the cardboard parts than for brass parts. Before that
can be done, I need to add the wheels, which requires a lot of
handling ... June 2020 - Caster-wheels - The (more or less) central
pivot determines its rotational axis, but the weight of the gun is
actually supported by four (kind of) caster wheels running on
cast-iron rails bolted to the bottom of the barbette. The rails
had been turned already a long time ago. The forks for the
caster-wheels were fabricated from laser-cut cardboard. The wheels
themselves are simple turned steel discs with a groove.
For the assembly, the rails were taped down onto an appropriately
scaled print-out of the original plan of the vessel and carriage
fixed with a clothes pin. The wheels and forks are temporarly
united by axels made from short lengths of copper wire. The
casters then were cemented under the carriage in the correct
position with respect to both, the rails and the carriage frame,
using again varnish.
The wheels will have to be removed again before painting the
carriage, because they will be left in bright steel. I do not
know, whether this is correct for the flanges of the wheels, but
it gives the whole arrangement are rather ‘technical’ look. The
axles with cylindrical end-caps have already been prepared from
steel rod and will be installed during the final assembly.
Stiffening brackets added over the
caster-rollers
Supporting brackets and
rods for working the training gears
Rollers
in brackets to lead the running-in tackle
The
lower carriage with the gratings installed
Lower carriage
temporarily placed into the barbette
June 2020 - More details on the lower carriage - While I
was drawing some additional parts to be cut with the laser, I
realised, that I had completely forgotten the stiffening brackets
for caster wheels. They are essential elements in the
construction, as the wheels each have to carry around 15 tons of
the total weight of the gun. The brackets were fabricated from
steel plates and forged(?) angles, fabricated on the model from
tiny pieces of Canson-paper cut with the laser.
There were also two brackets needed for the operating lever
including connecting rod of the gun training mechanism and for the
clutch that connects the cranks below the barbette with the gun.
The latter allows to connect gears for two different speed ratios,
a high ratio for fine weather and a low ratio through as
self-locking worm-gear for foul weather. A quite sophisticated
arrangement actually, but as nothing of it will be visible on the
model, it was ignored.
Connected to the gun training mechanisms is also a kind of capstan
to help run-in the gun. A tackle is hooked into each side of the
upper carriage and the runner lead by two guiding wheels into the
lower carriage and onto the capstan. The wheels were turned from
steel rod and their supporting brackets cut from Canson-paper. I
meant to closely reproduce the original design, but in the end had
to simplify it, because the parts were simply too small to
laser-cut and handle. Because they are so flimsy that had to be
put into place now and will have to painted over.
Finally the gratings were installed. Their brackets have flaps for
glueing. The 'glue' used was again zapon-lacquer, which results in
a surprisingly strong joint. The platform for the gun-layer was
only put up for the photographs. It has not been attached yet, as
it is too delicate and would impede the painting and the handling
of the carriage.
The gun barrel and lock
March 2007 - Because
there will various visible areas of bare metal, the material of
the original, that is steel, was chosen. A piece of round
bar was faced, centred and rough drilled for the bore. This hole
served as a protective counter bore for the tailstock centre
during the following turning operations. In order to get a good
roughening finish the automatic feed was set up. Unfortunately
the minimum feed per revolution on the watchmaking lathes is
still too high to get a 'mirror' finish. One day I have to
construct some sort of reduction gear. The outer part of the
barrel has slight taper (1 degree included angle) and the
top-slide was off-set for this operation. For rounding off the
ends of the rings the LS&Co. hand tool rest came to good
use. The work was finished off with fine wet-and-dry paper
(remember to cover ways!) and steel wool. The bore was bored to
diameter using the slide-rest and micro-boring tool. I had
originally envisaged to also show the rifling, but a quick
calculation told me that for a 1 mm bore and 72 rifled fields I
would need a tool edge just over 0.04 mm wide ...
Races and rack
provisionally in their place inside the barbette
Facing and
centring a piece of steel rod for the gun barrel
Rough drilling
of the gun barrel
Turning the
barrel using the automatic fine feed
Taper-turning
with
off-set slide rest
Rounding
the
'rings' using a hand turning rest
Boring
the barrel using a micro boring tool
Set-up
showing for milling the seat for the lock
For drilling holes for the trunnions
and milling the seat of the lock the diving head was set up on
the slide-rest. I could have done this operation on the milling
machine, but on the lathe the dividing head is centred
automatically. The outer end of the barrel was supported by the
arm with an appropriate centre fitted. The resulting shape from
the milling operation looks like a keyhole, but something like a
mushroom shape with sharp edges is required. This was achieved
by hand filing. For the next operation the set-up had to be
transferred to the mill anyway: milling the seats for the square
trunnions. The trunnions merge in a concave curve with the
barrel. The trunnions were turned up on the lathe as disk with
two round stubs protruding from either end. In the dividing head
on the mill the disk was milled square to the size of the seat
(or rather the other way round). These parts then were
soft-soldered to the barrel. Back on the mill the concave curves
of the square part of the trunnion were milled using a miniature
ball-head cutter, rotating the barrel in the dividing head.
Aiming a gun in these days was a rather
primitive affair, using just simple sights. The sights (two of
them on either side of the barrel) consisted essentially of a
round bar with a sliding rod to give the elevation. The beads
(mounted near the trunnions) were observed through a ring of
inverted U-shape on top of the rod. The bar was screwed into a
notch in the barrel. Now, drilling into a round at a tangent is
nearly impossible without deflection and breaking the drill (0.3
mm!). Therefore, I ground flat a broken drill bit to make a
make-shift micro-mill and sunk a start hole. This was finished
with an ordinary drill.
Close-up of the milling
operation in the dividing head with support
Working drawing
and files used to finish the lock seat
Milling the
square part of the trunnions
Milling the
seat for the trunnions
Trying
the trunnion
Milling
the concave transition between trunnion and barrel
Milling
the seat for the sights
Drilling
the
seats for the sights
Round-
milling the lock piece
Cutting
off the finished lock piece
The next thing to be
tackled was the lock piece. This 'wedge' has a rather complex
shape with a flat front, but a round back and various recesses
and cut-out. I decided it would be best to undertake most of the
machining operations while it is still attached to some (round)
material that can be easily hold in a collet. The round back was
milled on the mill's rotary table after the various coaxial
holes had been drilled and the flat sides milled, all in the
same set-up. For machining the other recesses the piece had to
transferred to the diving head on the mill. The large ring was
also turned up and two holes drilled into it for seating the
circular rack that forms part of the elevating gear.
The most time consuming
part turned out to be the cover piece for the lock, which in the
prototype was fastened by five hexagonal head bolts. It holds
the moving and locking screws in their place. It took me four
tries before I produced a half-way satisfactory piece. Soldering
the microscopic bolts (0.4 mm head diameter) in place got me
quite a few grey hairs. Finally a fake locking screw was turned
up and the moving screw, which moves the lock in and out, was
faked from a couple of drilled-together 0.1 mm copper wires,
covered in a thin layer of solder to make them look like steel.
The various parts of the lock were assembled using
lacquer and cyanoacrylate glue.
Milling square and
hexagonal bolts
Facing the
locking screw in special protective brass collet
The
(almost) finished gun barrel with its lock
Part
view of the drawings for the photo-etched upper
carriage frames
Surface
etched frames for the upper carriage
Filler
and covering pieces laid out for soldering
Assembled
side
pieces and ties laid out
The upper carriage
Throughout 2008 - Much
time has been spent on re-drawing the carriage as templates for
etched parts. After the etching process has been more or less
'mastered', surface etched parts of sufficient quality were
produced.
February 2009 - The side pieces
have been assembled. A filler was sawn from 0.8 mm brass sheet
and the etched covers soldered on. Then 'rivetted angle-irons',
from etched parts were soldered on. These will connected by
tie-plates. The frame is also strengthend by horizontal ties.
These are composites from several etched parts in order to show
the rivetting. The horizontal ties were soldered to the side
pieces, while the bulkhead-like ties were glued in because it
would have been to difficult and risky to bring the heat for
soldering at the right places. The covers for the
trunnion-bearings were bent from an etched part and soldered
together.
The upper carriage was further
kitted-out with wheels, the gears etc. The front and rear
rollers were turned from steel to give them a real 'steel'
appearance. On the prototype the rear rollers sit in excentric
bearings that allows them to be brought into to contact with the
rails on the lower carriage: when being fired the upper carriage
slides back on these rails, the rollers allow it to roll back
into the firing position.
Assembled
carriage
from the rear
Assmbled
carriage
from the front
Carriage with the barrel in place.
Note the trunnion bearings cover (not yet trimmed
to lenght)
Added the rollers plus the sockets
aft for the lever that is used to turn the
excentric bearings of the rear rollers
March 2009 - The gears were cut
from brass stock in the milling machine with the help of direct
dividing head and different division plates. The shape of the
teeth is not exactly correct, because I used a disc-shaped burr
as cutting tool. However, at this module (0.06), where the
teeths are merely pitched 0.1 mm apart, this is hardly
noticeable. The gear wheels are parted off from the stock on the
lathe. The gear segment that will be attached to the barrel was
produced in the same manner.
Cutting the gears for the gun
elevating mechanism using different division
plates
Cut-off wheels before further
machining
The elevating gear
train in GALSTER (1885)
The elevating gears on
the instruction model in Copenhagen
Krupp
factory photograph (TU Berlin)
The
step-wise forming of the dished handwheel
July 2020 - Completing the upper carriage
-With the lower carriage basically ready for
painting, I turned my attention back to the upper carriage.
The structural elements made from photo-etched parts had
already been constructed many years ago. Dito some of the
details had been fabricated more than ten years ago, or at
least partially. The elevating
mechanism consist of a double reduction gears and is driven
by a deeply dished handwheel with six spokes. These
reduction gears are duplicated on each side of the carriage.
The last wheel in the drive has a pinion on the inside of
the carriage, which acts on a gear segment that is attached
to the gun barrel. How the gear segment is guided is not
clear from the available drawings and the model in
Copenhagen. On the Russian Krupp-clones the arrangement is
slightly different.
There is
a friction-brake on the axle of the last large wheel of the
gear train, which is worked with a cross handle. How this
functions is not clear, but it presumably just pull the gear
onto the frame via a short thread that is cut onto the end of
the axle. On the starboard side of the gun there is a
brass disc and an indicator lever that somehow shows the
degree of elevation and presumably the range of the gun with
different kinds of projectiles and charges. Again, how this
indicator disc is coupled to the elevating gears is not clear,
as I do not have any suitable photographs. In any case, the
respective gear train will not be really visible on the model.
The dished handwheel
started life as parts photoetched from 0.2 mm brass. In order
be able to bend each spoke into the dished shape, a former was
turned from some round steel and set up on the watchmakers
‘staking tool’. The spokes were pre-bend by hand and then
finally pulled to shape using a hollow punch. The parts then
were chemically tinned and soldered together with the aid of
some flux.
The remaining parts,
such as the axles, are simple parts turned from steel rod for
strength, as they are quite long compared to the diameter.
August 2020 - The
gear segment for the elevating mechanism of the barrel was
produced by turning a short piece of copper pipe that I happened
to have in stock to the correct inside and outside diameters.
The teeth then were cut on the micro milling-machine using the
dividing head in a horizontal position. Then slots were sawn at
the angular distance required and then a slice of the required
thickness parted off. The ends of the segments were finally
filed to shape. The copper then was tinned in self-tinning
solution to resemble steel. For the brackets with which the gear
segment was attached to the reenforcement ring of the gun barrel
a piece of brass rod was turned out to the correct inside
diameter. On the mikro-mill with the dividing attachment in
upright position the other faces were milled to shape. Finally,
the individual bracket were sawn off with a circular saw at the
correct thickness. The parts, which are just over 1 mm long,
were chemically tinned to adapt them somewhat to the steel
colour of the barrel. As they will not have to withstand any
mechanical forces, they were glued to the reenforcement ring
with zapon lacquer. There were still a few
details missing on the upper carriage, for instance the
indicator disc for the elevating mechanism. How this indicator
is coupled to the elevating mechanism I was not able to find
out. It is not shown on the drawings, it is not visible on the
model in Copenhagen, and the respective parts are missing from
the guns in the Suomenlinna fortress. There was probably a
gear train on the inside of the carriage. For this indicator
disc a piece of 2 mm brass rod was faced off and a mock
gradation engraved with a toolbit turned onto its side in 6°
steps. There is a steel indictor lever (the function of which
is not clear to me, either the disc turned or this lever,
probably the former). For this a steel disc was turned with a
short arbor and transferred to the micro-mill, where the shape
of the lever was milled out. This indicator disc seems to have
been fitted only to the starbord side of the carriage. Furthermore the
brake-handels for the elevating mechanism were missing. A
short piece of 0.25 mm diametre copper wire was flattend in
the middle with a 0.8 mm diametre punch in the watchmaker’s
staking tool. The resulting round flat part was soldered to a
short distancing bushing and turned cap glued on from the
other side.
Progress in homeopathic
doses: I realised that I forgot the the two steps at the end
of the upper carriage. So, the parts for the frame were
laser-cut, pieces of tea-bag mesh inserted and the assembly
attached to the carriage with lacquer.
(Almost) all the parts of the
elevating gear laid out
The
elevanting gear provisionally assembled
Engraving the indicator disc for the
elevating mechanism on the lathe
Steps for the gun-layer
September 2020 - Assembly of the gun
I realised now that I had assembled so many tiny parts for the
gun, that it became difficult to not loose them and to remember
what they were for. Some of the parts indeed had been made years
ago. Therefore, I will proceed now to paint the parts and to
assemble the gun, which then will be placed as a whole into the
barbette, once the model is getting close to be finished.
The gun carriage will be painted green, as
evidenced by some contemporary builders’ models and a somewhat
later instruction manual. The hue of the green is another
issue. It was probably based on chrome oxide green.
The barrel of these breech-loading guns was scraped clean,
then wiped with vinegar until a brownish oxide layer
developed. The process was repeated several times and any
loose ‘rust’ wiped off. Finally, the barrel was rub down with
lineseed oil, effectively producing in situ a paint with
ferric oxihyroxide and ferric acetate as pigment. The
resulting colour would be something like caput mortuum. This
is the way the barrel of the demonstration model in Copenhagen
seems to have been treated. Moving parts and mechanically
relevant surfaces were keept clean carefully, of course. I
will, therefore, lightly spray the barrel in Schmincke caput
mortuum.
All parts temporarily assembled had to be taken apart for
painting first. After selecting a green for the carriage, all
the parts were given several light coats with the airbrush
until a uniform colour and sheen was achieved. Not so easy on
some of the complex parts. After letting it thoroughly dry,
the paint was scraped off from those parts that are meant to
be bare metal, but could not be masked off, due to being
difficult to access.
The assembly then proceeded from the inside out
on the lower carriage. First the parts for the hydraulic
recoil brake were installed. I decided to deviate from the
prototype and not to install the protective tunnel over the
piston of the brake in order to show the metal-work. I think
this small bit of artistic license is permissible. All parts
were put together with small blobs of zapon-lacquer, which
dries up quite invisible.
Next the spring buffers were installed. Putting
in the tiny hexagonal nuts required a very deep breath each
time.
Flipping the carriage over the caster-wheels were
put back, but this really taxed my patience. The wheels are
held in place by little flat-head pins inserted from both
sides. A simple through-pin would have been easier to install,
but wouldn’t be quite prototype fashion.
The lower-carriage was very difficult to
handle due to the flimsy and delicate grilles and steps. One was
broken off in the process, but luckily attached nicely again.
The rail on which the upper carriage runs would
be bare metal. Here the limitations of using cardboard as
structural element shows its limitations. If I had used etched
brass parts, I would have chemically tinned them before
assembly and now could have just scraped off the paint or
masked the area before painting to reveal the metal. Now I had
to simulate it with paint and a soft lead pencil. I am not
entirely satisfied with the result, but can’t do anything
about it now anymore.
Overall, I am somewhat ambivalent as to the
merit of using cardboard. The surface and cut edges simply are
not as smooth as those of metal or plastics, such as bakelite
paper or styrene. Unfortunately, styrene could not be cut with
my small laser-cutter.
When proceeding to the
upper carriage, I noticed a couple of mistakes I made years
ago, when putting it together. Two of the transversal members
were installed at a wrong place. The wheels of the carriage
would have not touched the rails otherwise. When trying to
rectify this, the whole assembly gave, but luckily I managed
to put it back together without permanent damage.
Another issue also
arose: one should not work from drawings alone, particularly
in a project that streches so long as this one. It turned out
that the carriage was a couple of tenths of milimeters to
narrow and would not fit over the lower carriage with its
guiding plates. I should have properly verified this, when
developing the parts for the lower carriage. With a bit of
bending and tweaking it could be made to fit, but cobble-jobs
like this leave parts behind that are not as crisp as they
should be.
Painting the gun barrel
turned out to be a major nightmare. I did not want to prime
the steel in order to not loose its metallic appearance.
Usually, acrylic paints dry so fast that there are not serious
issues with rust formation. When I first applied the first
coat it looked ok, but the next morning it had developed a
mottled appearance. The same phenomenon reappeared after each
coat, but somewhat less. I attributed it to the fact that the
bottle of paint was actually almost 25 years old and it had
not been sufficiently mixed. In the end I cleaned off the
paint and began again, but with the same result. Once more I
took the paint off and then sprayed it, but without agitating
the bottle, thinking that some of the pigment might have
coagulated – same result. Finally, I decided to lightly prime
the barrel with zapon-lacquer to isolate the steel. This forms
a very thin and virtually invisible layer. This did the trick,
but the priming was not done carefully enough and some spots
were left bare – with the result that those areas appeared
mottled again. I tried dipping, but this leaves a too thick
layers in corners etc. Eventually, I managed to obtain a
reaonably even layer – one has to work very fast and going
over areas already treated is virtually impossible due to the
rapid drying. It is also very difficult see, whether one has
covered the whole surface. In conclusion, I think the pigment
of caput mortuum, which probably is the mineral haematite
(Fe3O4) has reacted with the steel (Fe0) leading to the
mottled appearance. However, I managed to reproduce the
appearance of the barrel of the demonstration model in
Copenhagen reasonably well, considering the small scale.
A few of the flimsy and easy to break off details
have not yet been installed and some levers to work the
mechanisms still have to be fabricated.
The close-up photographs also show a lot of
dust and fluff that need to be cleaned and that the paintwork
has to be touched up here and there.
The
painted and (part) assembled gun
October 2020 - Ammunition and ammunition
handling
Thanks to the book published in 1886 by Carl Galster, we are
relatively well informed about the ammunition of the German naval
artillery of that time. The WESPE-Class was the only class of
ships fitted with the Rk 30,5 cm/l22. According to Galster, three
types of projectiles were available for these guns in the late
1870s/early 1880s: a) armour-piercing shells, b) shells with a
time-fuse, and b) dummy shells for gun-drill.
All shells had two copper guiding rings that would be squeezed
into the rifling. One ring sat shortly above the bottom and the
second ring where the cylindrical part would transit into the
ogival part of the shell.
The armour-piercing shells were cast in a particular way to harden
the steel from which they were cast. They were hollow, but with
only a relatively small chamber for powder in the rear part. The
nose was cast solid. However, at that time functional impact fuses
were not yet available, so the shells were filled with a mixture
of sand and sawdust to give the approximate weight distribution as
a powder charge would give. The threaded hole for the fuse in the
bottom was simply plugged. Armour-piercing shells were painted
blue.
The ordinary shell had thinner walls and consequently a larger
power-charge. The nose was threaded for time-fuses. It is beyond
the scope of this building-log to discuss the fuses in detail, it
suffices to say that these were made from brass. Shells were
painted red and when actually charged with powder marked with a
black ring around the nose.
Dummy shells were ‘seconds’ of ordinary shells filled with a
sand-sawdust mixture to give the same weight as a real shell. The
hole in the nose was closed with a wooden plug. They were painted
black all over.
Powder charges were supplied in cylindrical bags. Each bag weighed
46 kg. Up to two bags could be loaded, allowing to adapt the
firing range. The bags were stored and handled in cyclindrical
boxes lined with zinc sheet or where made from German silver.
A total of five shells were kept ready in the
open barbette. I would assume that these would be only the
armour-piercing and drill ones, as the fuse of ordinary shells
would be rather exposed to the elements. I set out to make six
shells in total, three armour-piercing and two drill-shells, that
were stored in their respective racks in the barbette. The sixth
is an ordinary shell to be placed in the shell-cradle under the
crane.
My preferred steel in the workshop are copper-coated welding rods.
The copper-coating is very convenient here, as their diameter of 2
mm is exactly the scale diameter over the copper guiding rings.
The nose was turned free-hand with my special Lorch, Schmidt &
Co. graver holder. The shells are 4.8 mm long. For the live shell,
a little brass button was turned and inserted into a pre-drilled
hole in the nose.
Shells
in handling cradles
Powder
bag
Free-hand
turning of the shell
Gun
drill, showing the cradle
The
finished ready-shells
It not clear, how the heavy shells (weighing
around 330 kg) were handled inside the ship and hoisted to the
level of the barbette floor. The crane on the gun-carriage
does not actually reach over the access-hatch to the
shell-store through which the shells presumably were hoisted.
The drawings are not clear on the various hatches in the
barbette and over the shell-storage, because of various
elments being hidden behind others and therefore not drawn. I
will have to live with this ignorance.
On the decks, the shells were wheeled around
in trolleys. In the Rigsarkivet in Copenhagen a blue-print (in
the true sense of the word) for such a trolley has survived. The
trolly forms a cradle that can be hoisted by crane to the breech
of the gun. At the rear of the gun two hooks are provided (not
realised on the model) into which the cradle hooks. The shell
then can be pushed into the gun with a rammer.
The parts for the trolley where laser-cut and
assembled using zapon lacquer. Effectively the trolley was built
around the shell for rigidity. A hole was drilled into the shell
to secure the hoisting ring.
The racks for the ready shells were laminated together from
laser-cut pieces and painted white. The retaining bar was made
from flattened pieces of 0.3 mm diameter copper wire that was
chemically tinned. In theory, each individual shell should have
had its own retaining ring (keeping in mind how important it is to
restrain these 300 kg beasts in anything but the slightest sea),
but after several attempts to put these into place without
damaging the paint-work on the shells too much, I gave up.
Flattening the wire reminded me of another pending workshop
project, namely a micro-rolling mill to produce metal strips of
consistent width and thickness from soft wire.
Deck
Furniture
Bollards
May 2007 - The ships was
fitted with four pairs of bollards of square cross section; two
at the rear and two on the raised quarterdeck. Luckily a good
rather close-up photograph of the real specimen is available
(see main page). The bollards are milled from round brass stock.
Round stock was chosen as a starting point rather than e.g. flat
stock, because it can be held easily in the lathe for turning a
spigot on which, by which the part can be held for further
machining. Otherwise it would be difficult to mount such small a
part on the miller for machining five sides. The spigot is also
a convenient reference for machining and for fastening on the
model eventually. From the lathe the raw part is transferred to
the dividing head mounted on the milling machine. After each
pass with the tool, the part is turned by 90º or 180º depending
on requirements. Thus a square and symmetric part is produced.
For a final machining step the part is transferred back to the
lathe and the dome shaped head formed using a very fine file on
a roller-filing rest. The job is completed by rounding off the
corners using a not-too-hard rubber-bonded abrasive wheel (CRATEX)
in the mini-drill. Remaining machining burrs are removed by
offering the part to wire brush wheel.
Turning the raw bollard
Mounting the
raw bollard in the dividing head on the milling
machine
Milling
operations: first squaring, then producing the
waist
Rounding
off
the cap
The
roller filing rest
Finished
bollards
and part of working drawing
Drilling
the
holes for the bases
September
2008 - The base for the double bollards were intended
to be a surface etched parts, but I was not happy with the
results. So I decided to make them from solid brass. Solid brass
was easier to handle for machining than brass sheet.
Nevertheless the envisaged machining operations prompted me to
make a couple of gadgets, fixtures, for the mill and the lathe. Milling around the edges
or on top of flat material always presents work-holding
problems. Worse, if several identical parts have to be
produced. Hence I divined a work-holding block with several
clamps and stops running in a T-slot. Similarly holding small
parts for cutting off on the circular saw is tricky and best
done on the lathe with a special saw table clamped to the
top-slide. This saw table allows parts to be safely clamped
down for cutting.
The
three parts of each bollards were soft-soldered together.
Drilling
set-up
Milling
the beading
Sawing
off surplus material
Parting
off the individual bases
Milling
a bevel
Parts
of double bollards
Work
holding for soldering
Bollards,
chain
stoppers and spill
Chain-stoppers
May 2007 - One
pair of chain stoppers is located immediately behind the hawse
pipes as usual. A second pair is placed above the chain locker,
which is located immediately in from of the armoured barbette.
The bodies of the stoppers are rather complex castings, calling
for some complex machining operations in model reproduction. The
same basic technique as for the bollards was used. Given the
complex shape, however, machining is not possible in one set-up.
for certain operations the axis of the spigot has to be
perpendicular to the milling machine, while for others, such as
drilling it has to be parallel. For the latter and for milling
the various slots, I choose to transfer the dividing head to the
lathe. This has the advantage that its centre line is at the
centre of the lathe spindle.
The
slots were milled using a micro-tool made from a broken carbide
drill, the end of which was ground flat. This results in a
non-ideal clearance of 0º, while the cutting angle and side rake
are that of the original drill bit. However, not much metal is
removed so that this doesn't really matter here.
Milling the profile of the
chain stopper
Milling the
slots on the lathe
Milling
bits and product
Squaring
the part on the upright collet holder
Close-up
Round-milling
on
the rotary table
One set of stoppers was milled from brass,
while for the other one I used PMMA (PLEXIGLAS®,
PERSPEX), the main reason being that I ran out
of brass stock. However, genuine PLEXIGLAS®, is pleasant material to machine and easy on the
tools. It holds sharp edges and it easier to see what you are
doing than on the shiny brass. Acrylic paints seem to key-in
well - basically its the same molecule, of course. On the
downside one may note that small and thin parts are rather
brittle. Using diamond-cut carbide tools gives a nice smooth
finish, but normal CV- or HSS-tools can also be used, of
course.
While for the bollards and the front pair of
stoppers the spigot could be on the geometric centre of the
part, making it easy to measure while machining, for the after
stoppers I had to place the spigot to the centre of the pipe
down to the locker, so that the concentric rounded edges could
be milled. The pictures show this operation.
October 2008 - The
stoppers have now completed with etched brass releasing
levers, etc. The fore stoppers were also soldered to surface
etched base plates.
Undercutting
using a micro saw bit
Stoppers
compared
against a 5 Euro-Cent coin
Drilling
the
hole for the release lever
Finished
after
stopper
Etched
fret with stopper base plates (bottom left) and
levers (bottom right)
Finished
fore
and after stoppers (right column)
Anchor
capstan
August
2007 - One component that always has puzzled
me somewhat as to their manufacture in a model has been the
sprocket on capstans. While the geometry on horizontal
windlasses is quite simple, with suitable depressions for the
chain links around the circumference, the sprocket on a capstan
is a complex affair. In any case the capstan head cannot be
manufactured in one piece. So I broke it down into three pieces:
the spill head, the sprocket and the base drum with the pawls.
The whole capstan has more pieces including four guiding rollers
and a finger to pull the chain off the sprocket. The cast base
on the prototype will be reproduced as a surface-etched part.
The sprocket started out as a 2.5 mm brass rod taken into the
dividing and into five notches were milled to produce something
like a five-pointed star (these sprockets typically have five or
six arms). The notches for the horizontal links were cut on the
lathe with a forming tool. The sprocket then was faced and
drilled to fit onto the capstan stem. The next step is cutting
it off. This produces some burrs that need to be taken off.
Luckily I have collected over the years almost every type of
work-holding device that was ever made for the watchmakers
lathe. Here the insert jewel chucks came handy to hold the 2.2
mm by 0.6 mm sprocket for facing-off.
Milling the sprocket, 1st step
Milling the sprocket, 2nd
step
Cutting
with a forming tool
Drilling
the sprocket
Facing-off
the sprocket in a jewel chuck
Capstan
head ready for cutting off
The capstan head is a simple turning job. The curved
surfaces are pre-cut with appropriate lathe tools and then
finished with very fine files. Incidentally, the implement shown
on the appropriate picture is a rare miniature micrometer, also
coming from the watchmakers toolbox and very handy for measuring
narrow recesses and the likes. They came in sets of three, the
other two are a depth-micrometer and one for measuring the width
of notches respectively.
Finally, the three parts are soft-soldered together.
September 2008
- Again the guiding rollers are a simple turning job.
The shapes were produced with a free-turning graver and by
rotary milling in the dividing head. In the meantime various
etched parts had been produced, including the base plate made up
of two different superimposed parts and minuscule pawls. Also a
chain separator from 0.3 mm copper wire rolled flat was
produced. The various parts were soldered together.
Assembled
capstan head
Shaping
the head of the rollers by rotary milling
Set-up for
shaping the rollers using the geared dividing head
Etched
fret with capstan base plate (top left) and pawl
(bottom centre)
Finished
Capstan (bottom left)
Engine-room
telegraph drawings, original in the Norsk Maritimt
Museum, Oslo, and the two telegraphs on the model
October 2019 - Engine-room telegraphs.
On
the ‘official’ lithograph of SMS WESPE from the
early 1880s an unsual form of engine-room telegraph was drawn.
It has a horizontal dial. In the earliest known photography of
the ship during fitting-out, the telegraphs had not yet been
installed.
A short while ago I discovered during a visit to
Oslo in the Norsk Maritimt Museum a very similar telegraph on
display. Unfortunately, the legend is not readable on my
image. I seem to remember that the inventor or patentee was
named. A search on the Internet and in my library did not
produce anything, so I would be grateful, if anyone has an
idea, who the inventor or patentee might have been.
The telegraph was
redrawn from the lithography in order to serve as a working
drawing with measures to guide the lathe operation.
The whole telegraph
seems to have been made from brass and accordingly the model
was turned from brass. The indicator arm and follower were
made from flattened brass wire and the ‘wooden’ handle built
up from PVA glue.
SMS WESPE
had two telegraphs, one for the starbord and port engine each,
of this early twin-screw naval vessel.
Binnacles
from the 1880s lithograph
Working
drawings for the binnacles
Milling
the octogonal columns
Milling the glass hood in the shape of
an octogonal pyramid
Cleaning
up after painting
The parts
of the binnacles
Binnacles temporarily
assembled
November
2019 - Binnacles. SMS WESPE was originally equipped with
three binnacles, one on the bridge, the mother-compass on a sort
of pole in front of the engine-room skylight, and the third one
in front of the emergency steering-wheel at the stern. In the
1890s a fourth binnacle was installed on a platform atop the
engine-room skylight, but is left off here. As SMS WESPE was
built in 1876 the original binnacles lack the conspicuous
compensation spheres, that were only invented in the 1880s by
Lord Kelvin. Also other type of compensation gear is not visible
on the lithographs and the earliest photograph. A photography of
the early 1890s shows a much more substantial binnacle in front
of the emergency steering-wheel, which preumably now houses the
compensation gear and also sports the compensation spheres.
Originally, the compasses must have been illumanted by petroleum
lamps, but from the lithographs it is not clear, where these
lamps would have been attached. At least there are exhaust
funnels on top of the binnacles, which have disappeared in later
photographs. This seems to indicated that electrical
illumination might have been introduced, when a dynamo was
installed on board in the early 1890s for a search-light.
For
the model the individual binnacles were redrawn from the
lithograph in order to serve as a basis for working sketch to
guide the lathe- and mill-work. One needs to keep in mind that
the total height is somewhere between 10 and 15 mm.
The columns presumably were made from mahagony and were turned
from brass rod before being transferred to dividing head on mill
to cut the octogonal shape.
The actual compass was made, as usual, from brass and so on the
model. Body and funnel did not provide a particular challenge,
not considering the small size. To the contrary, the glass hood
with its narrow frames of perhaps 15 mm width on the original.
The body was roughly turned from Plexiglas and then transferred
to the mill. Here the octogonal pyramid was milled. Using a 0.3
mm ball-head burr narrow grooves were cut into the edges and
these grooves filled in with brass paint.
Once the paint had thoroughly dried, the faces were very lightly
milled over, which resulted in sharp narrow brass strips at the
edges. This is a technique that I copied from making engraved
scales.
Originally I had the crazy idea of placing a miniature
compass-card underneath the Plexiglas hoods, but even without
it, assembling the binnacles was fiddly enough.
January
2020 - Steering-wheels. All the boats had two sets
of steering wheels, one on the bridge and the emergency
steering-wheels at the stern. Both stands had double wheels that worked in the
traditional way on drums and ropes. There is a rather good
photograph of the emergency steering position, which allows to
deduct the details of the wheels. On the model these wheels
are rather delicate affairs of only just under 10 mm diameter
overall. I had been considering many different ideas for
different kind of materials for fabricating them. Machining
the slender spokes seemed a daunting task. Photo-etching and
assembling them from different layers seemed a more realistic
proposition. It then appeared to me that laser-cutting might
be also an option, as I had recently acquired a cheap, small
machine.
After some tests with the laser-cutter, I finally
chose 120 g/m2 Canson-paper, which is 0.15 mm thick and has a
smooth surface. It cuts well with the laser-cutter, as it is
not ballasted with inorganic material, such as barytes. Some trials were needed to determine the right
cutting parameter combination of contrast, laser-power and
cutting depth. One should assume that for a simple B/W-picture
the contrast should be 100%, but somehow changing the contrast
setting changes the width of the cuts. For this reason the
final dimensions of the parts depend on the contrast setting.
Laser-cutting is
contactless and the cut-out parts are not moved during the
cutting process. Therefore, it is possible to cut them out
completely and in contrast to the photoetch-process they do
not need to be attached to some frame. When designing the
image with which the laser-cutter works, one needs to consider
all these factors that sometimes can only be determined by
trial and error.
The wheels are built up
from five layers in order to simulate the joinery work and to
arrive at the necessary 3D-rendering. The core part was
thickened by two more layers, the outline of which was drawn a
bit smaller to simulate the profiling of wheels and handles. A
further layer on each side simulate the rim and hub. The
individual layers were glued together with zapon-lacquer,
which impregnates and stiffens the paper. Unlike many other
glues, this lacquer only forms a very thin layer, not adding
to the thickness of the wheel, and the parts can be adjusted,
as long as the lacquer has not dried.
The prototype
steering-wheels were re-enforced by brass-rings screwed onto
each face. My intention was to make these rings from real
brass shim (remember: only real metal looks like real metal
...). However, I did not manage to cut so narrow rings from
0.05 mm brass-shim. In the end, I bored out a piece of round
brass stock to 6.8 mm and turned down the outside to 7.2 mm.
From this tube with 0.3 mm wall thickness, slices of 0.1 mm
thickness were parted off. After a few trials to get the
settings right, this worked fast and repetable. The rings were
deburred on 600 grit wet-and-dry paper, ground finely on an
Arkansas-stone and polished on a piece of paper with some
polishing compound. The brass rings were glued on with
lacquer.
The axle including drum
for the steering rope were turned from brass. The wheels will
be spray-painted painted all over and then the paint rubbed
off from the brass rings. This will nicely simulate the rings
let into the wood as per prototype.
Laser-cutting
machine
Laser-cut steering wheels
Components
of wheels
Steering-wheels and brass reenforcement
rings
Assembled wheels and
components
Gratings:
JPG-mage as input for the laser-cutter
Steering-wheel
pillars: JPG-mage as input for the laser-cutter
Machining the bearing caps in a
‘jewelling’ collet
Shaping the covering cap of the
wheel-axle using a cup burr
Wespe-Class Armoured
Gunboat: The Model 
