wefalck

I would not use shellac and waxes on acrylics. Their thermal coefficient of expansion are different. In addition, shellac is too glossy - unlike on wood it cannot be rubbed down on paint. As for touching up: I avoid mixing paints, which removes the variable of getting the colour right. Of course, one would see touching up with a brush on a larger spray-painted surface. As I prefer to give my models a workaday look, the sprayed surfaces would be treated with washes (applied with a brush) of other paint anyway, so that touching up is not an issue.

But the flaking is mainly due to poor adherence to the surface. So that would not change with a an additional coating, just the flakes may be bigger. Obviously I don't have a life-time experience yet, let alone that of several life-times , but I have spray-painted with acrylics a metal hull back in 1989 or so and it still looks like on the first day, thirty years later.

To my knowledge the operational log-books have been lost, when the archives of the Admiralty were plundered in the days after the end of WW2. So we don't know, whether they ever practiced this settling on the mud-flats and what the experience with it was. The boats never saw real action, as they were decommissioned long before WW1. Half of them were stationed in the Baltic and other half in the North Sea, but they were effectively commissioned only for short periods of exercises. There are known sandbanks that would have been safer for the pupose than the actual mud-flats. I would have picked a sandbank close to a known tidal channel with the chance of a high current washing away the sand. In peace time these channels were and are marked with 'pricks', kind of brooms stuck upside-down into the banks of the channels. However, during war time all such marks were removed. So, in the Wadden Sea they would have certainly needed a pilot with pretty good local knowledge, probably a local fisherman. I gather, these 30.5 cm-guns were among the heaviest of their time, only surpassed, I think, by the 45 cm-guns of the Italian DUILIO and DANDOLO. I may mix this up, but I seem to remember that they built a special (still existing) steam-crane in Venice to insert these guns.

Acrylics typically take long to form a strong coating. There are two processes happening, the acrylics dispersion breaks down and the molecules begin to form an interlinked network and at the same time the 'solvent' evaporates, which becomes more difficult as the layer shrinks and the water molecules become trapped in it. Therefore, it may take several weeks before full strength is reached. It depends on the thickness of each layer that is sprayed on. Artist's acrylics (which includes modeller's acrylics) are made for decorative purposes, not for surface protection. Therefore, they may be not as scratch-proof as other types of acrylics. For a working model, I would be concerned about the paint being scratch-proof and adhering very well to the underlying surface. For a stationary model this is not that much an issue in my opinion. It really depends on how rough your handling is during the building process. Personally, I delay painting as much as possible, until all parts are made and fitted. Some modellers prefer a uniform sheen (usually matt or satin) all over their models. Again personally, I like to indicate different prototype materials by different levels of sheen (never really high gloss though). There may be a need to cover shiny spots of glue etc. over paint and in this case one may want to apply some varnish. In this case I would go for acrylics varnish, preferrably from the same manufacturer. Any unnecessary layer of paint might drown out surface details - airbrushed acrylics are really good to bring out surface detail, when sprayed on in thin layers. Acrylics are quite forgiving, when it comes to mixing layers of different types of paint, if one obeys to some basic rules: - spray thin layers to speed up curing - acrylics are pervious to water vapour, so water can evaporate through subsequent layers of acrylics; this may not be case when other types of paint are applied over acrylics, then water may become trapped and can cause problems with changing temperature. - obey the old painter's rule 'fat over lean' (as noted above already); acrylics molecules are hydrophilic and would not stick very well on 'fat' oil paints or enamels, which are typically lipophilic; oil paint or enamel over acrylics would also trap any residual water (see above). So in summary, unless you expect rough handling of your model during the construction or later, there is no need to 'seal' acrylics.

What is the purpose of this 'sealing' ?

Keith, the weight of the barrel incl. lock is 35.6 t (metric tons), the weight of the lock alone is 1.3 t. The total weight of upper and lower carriage together is 23.2 t. This means that with a loaded and manned gun close to 60 t would have needed to be controlled by the training mechanism.

You are right, the gun could be trained only through a relatively narrow arc. Otherwise, the boat should have had a much broader and/or deeper hull in order to take up the recoil forces from the massive gun. However, this would go against the foreseen tactical concept. At that time the naval strategic concept of Germany was entirely defensive (probably with France as the main anticipated enemy). The gunboats were designed as a kind of mobile detached fort. The main operating area would be the Wadden Sea, the tidal flats separating the German coast from the open North Sea. The heavy gun of these boats was meant to engage enemy ships before they could bring their own guns to bear, operating in the shallow tidal waters into which most enemy vessels could not follow. There were probably two tactical concepts: the gunboats would approach the enemy in shallow curved trajectory and once the enemy would pass through the line of the gun sights, one would fire. That is essentially the same tactics as used by the earlier rowing gunboats of Sweden, Denmark, France etc. Prussia had also such gunboats from the 1840s to the 1860s. The British Rendell-gunboats were designed for a similar tactic, as their gun could not be trained. The other tactic would be that the gunboats would retreat into shallow water, off the shipping lanes and let themselves fall dry during low tide. For this they had a flat bottom (for this they had German nicknames, such as 'mud bug'). When high and dry they would serve as gun platforms and to be able to do so, their gun neede to be able to be trained through a certain arc. The tactical concept was developed just after the Franco-Prussian War (1870/71), before the fish-torpedo became an operational reality. Their concept became largely obsolete, when the first torpedo-boats appeared in the early 1880s, as they themselves are vulnerable to such attacks. Nevertheless, their tactical usefullness was augmented in the mid-1880s by fitting them with an underwater forward torpedo-tube.

Thanks, druxey was faster ...

Thanks, Pat ... but close-up photographs are really unforgiving, as one can also see in the following ... ******************************************************************************************************** Further work on the lower carriage Back to the lower carriage. The (mor 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. Caster wheels prepared for assembly 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. Caster wheels in place 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. Caster wheels in place To be continued ...

The deck now looks rather mushroom-infested Did you experiment with image stacking now ? Or did you just use a telephoto-lense outdoors with a very small aperture to ge this depth of field ? I don't envy the crew to keep all that brass shiny. It seems that on SEA CLOUD they originally installed gold-plated taps etc. because it was less work to keep them clean ...

My first ride in one was back in 1962. The rear bench then was still strung with plastic ribbon like certain garden chairs ... I owned a 1972 one, my first car, from early 1977 until summer 1986, when I sold it for nearly the same price, for which I had bought it nine years early (ok, a lot of money went into repairs in between. Loved it. Speed certainly was not a merit of it, but I got through places and weather situations, where much bigger cars had to give up. Light-weight and most of the weight due to the engine on the driven front-wheels. I wa a geology student and used it for my field work, it served me almost like a 4WD. Once we some snow overnight in the mountains in late spring, everyone had changed back into summer tyres (I never had winter tyres) and I remember a Mercedes getting stuck on a hill - two people in the boot to balast the rear wheels, but still couldn't get away - still remember the acid look from the driver, when I simply drove past him and up the hill ... when travelling across Europe, I left the rear bench at home; for the night I drove to a camp ground, took the passenger seat out, put it behind the driver's seat and stretched out in my sleeping bag on an air-mattrass ... up hill my small-engine (498 cc, 23 hp) 2CV was struggling, but I 'made' most of the major Alpine passes, including the Cime de la Bonette, at 2860 m the highest European pass with a surface road ... in first gear and at 15 km/h. Downhill I was a lot faster and often had to push mountain-wise challenged flat-country drivers from The Netherlands and Belgium ... still no match for those mad local French drivers - I remember a 60 or 70 something year old farmer's wife in a Renault 4 chasing me on a mountain road ... how boring Alpine roads have become now in cars that have five or ten times the horse-power ...

'Fine detail plastic', at least in Shapeway's parlance is acrylic resin, right ? Then it should take acrylic paint very well, just like Plexiglass does.

Perhaps one could/should look also how such connection would have been done in real life. I gather this is a pump(-spill) related connection rod and cross-head ? Then the bolt with a cylindrical or semi-circular head would be either threaded at the other end and a sequence of a washer, a nut and a locking-nut would be screwed on, or, more commonly, the bolt would have a square slot; a washer would be put on and then a metal wedge would be inserted. Hexagonal nuts are easy to file from either thick-walled tube or drilled-out round brass rod. Washers can be produced with a hollow punch from styrene sheet or paper/cardboard. A wedge can be simulated by a tiny piece of styrene sheet. For the bolt I would use a brass or copper pin, but give it a more defined shape in an electrical drill. BTW, I would also file away the flash from the cast white-metal parts and straighten them a bit.

Personally, I would turn simple parts, such as the smoke stack, from brass - depending also on the size, as brass is quite expensive. However, complex 'free-form' shapes, such as cowl-vents are not that easy to machine from the solid. Here I see a lot of potential for the described technique. I wonder how well any putty would adhere to the nylon ? This could be critical for the longer-term stability of the parts.

At least here in Europe lead shot is being (or has been) phased out due to the environmental contamination it causes. I believe it is being replaced by tungsten (alloys). BTW, 'cannon balls' are not made from (cast) steel, but cast iron. Steel was only introduced when ogival projectiles were introduced together with rifled breech-loading guns. Only then they were machined, rather than being used as cast. The balls seem to have been usually painted in black oil-paint to prevent them from rusting, so that should not really look 'metallic'.

Why and since when cowl vents are painted red inside still seems to be an unresolved question. We have been discussing in various fora etc. for the Imperial German Navy, but the discussions remained unconclusive. At some stage white seems to have been common, apparently to serve as a light conduit as well. I have also seen black ones - e.g. the boiler-room ventilators on my SMS WESPE at least in the early years; presumably to make coal dust less visible. French ventilators in the 19th century seem to have been the same colour outside and inside. Another suggestion for the choice of red as colour has been that it resembles (faintly) the copper from which many early (smaller) ventilators were made.

You seem to be getting closer to my size range 👍 Yes, one can't really bore that well with a ball-endmill, but it also depends on how it is ground.

Keep venting ...

The kit presumably is based on the set of plans published by the AAMM: http://www.planeteloisirs-bg.fr/index_fichiers/pages/bateau/marie-jeanne-1.html I am not absolutely sure, but the above plans in turn may be based on a plate in Pâris' Souvenirs de la Marine.

Keith, this is a very simple machine. I started a separate thread on it: https://modelshipworld.com/topic/23478-miniature-desk-top-laser-cutter/ Essentially, it is a very simple piece of software that reads the image pixel by pixel, row by row. It's bit image driven, not vector driven.

Thanks, gentlemen, for your kind words ... ******************************************** 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. Best available image of the bow scrollwork and name-plate 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. Only available image of the stern scrollwork 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. Artwork for the bow scrollwork 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. Some examples of the (unused) laser-cut scrollwork and the name-plates 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. Scrollwork and name-plate in place 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. Stern scrollwork in place 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. To be continued ...

When it is only about protection from solar radiation, one could put a second light roof over the actual roof with a few inches of distance. The chimney effect should cool the lower roof. Solar panels for that second roof would generate some electricity too. That doesn't solve the problem of high humidity though. To my knowledge these mobile A/C units are rather inefficient and have significant carbon-footprint.

Somehow, I missed the last instalment. Playing around with paints of different sheen is a good idea. I've played with gloss, semi-gloss and flat acrylic varnish. Some people prefer their models flat all-over, but I think even at relatively small scales the different sheen of of different materials is noticeable and brings a model to life 👍

Well, the descerning owner prefers exclusive small producers ... we collect a case or two from time to time from https://www.vivino.com/max-cochut-champagne-aristide-de-saint-cyr-brut/w/6366721?year=U.V

Very good idea for turning/milling the legs from the solid ! Probably gives a much cleaner and crisper result than trying to fabricate it from sheet.