wefalck

Does your not have a top-slide ? Turning the whole carriage with the crank at the bed on the right seems to be rather cumbersome and it seems difficult to crank, keep an eye on dial readings and watch what happens. How do you turn the taper without top-slide ? Most of my turning of such things is done with a knife-tool that I grind from a HSS-bit. For such dimensions the width at the front should equal or be less then the shortest between two rings. The most used tool has a width of only 0.4 mm at the front and clearance on three sides. In this way I can turn to the left and the right without changing the tool. I normally make myself a dimensioned sketch and then decide on zero points for movements in both, x- and y-direction. I then note down in the sketch how much I need to move the carriage between the rings, taking into consideration also the width of the tool at the front. In order to avoid backlash issues, all the turning is done in one direction only. In this way I avoid measuring on the workpiece (at least for duplicates). With such a procedure you can turn out identical pieces within the accuracy limits of your machine. If the rings on the cannon need to be rounded, there are two options: you can use either a file to do that or using a forming tool in a secondary operation. As you don't seem to have a QCTP, chaning tools might not be such a good option though.

Some people also mill or plane the rough shape from a square billet and then slice it up to get the individual knees. The main stress occurs, when you are handling the pieces. Once in the model, stresses are of no concern.

If it doesn't have to be natural wood, there are various other materials, such as brass, acrylic glass or bakelite paper. If you find a dark brown version of the latter, it can look almost like wood, when polished. I am using it for blocks.

I don't know how it was done on your specific, but in in general metal brackets were fixed along the coaming and the cover fixed with battens that were wedged against the coaming with pairs of wooden wedged driven in from opposing sides. On the picture below you can see the arrangement on a somewhat later ship around the coamings of the skylight. http://www.maritima-et-mechanika.org/maritime/models/wespe/Laverrenz-20.jpg On the sailing ships of old, that would be at sea for months, the battens may have been nailed down in addition.

I gather it also depends on the absolute size you are talking about. Some people use the 'planking-first' strategy on small boats, where it might be difficult to cut a clean rabbet. Having said that, if you don't care about mimicking the real building techniques and are only interested in the appearance, a sort of hybrid strategy can be considered: rather than cutting a rabbet proper, you can put the keel and stem together from two pieces each, being the inbord and the outbord part respectively.

What wood are you using, that you are worried about splitting ?

Good progress. I somehow figured, that you would probably tighten the laminate onto the template with wire or string. Be cautious when working with ebony. It seems that ebony dust is not very healthy ...

There are different CAD systems, of course. If you work on a 2D CAD, the dimensions in one plane are not normally correlated with another plane. What I mean is that the body-plan is drawn separately from the plan of the waterlines. They are two independent drawings. This in turn means that you can make all the same mistakes as in hand-draughting. Only, when you use a 3D CAD system and print out different sections of the the same 3D body, everything should tally.

We are veering off a bit from the original subject of thread ... nevertheless the article quoted above seems to show an ordinary 2D pantograph engraving machine, though I didn't carefully look at all the details. As matter of fact, such engraving machines for door-bell signs, fountain pens, sports trophies (with special mounts) are an application of pantographs that persists until this day. The letters etc. to be engraved come in sets of templates. The machines and the special grinding machines for the engraving bits are still being sold. Otherwise, pantograph work has largely been replaced by CAD and CNC-milling or laser-cutting.

I have a pair of safety-glasses that have +2 lenses in them. There may be also stronger ones. They are very comfortable, like normal glasses and protect you, when working with machinery etc. I used to have safety-glasses with neutral lenses (being myopic), but found that with increasing age (or may increasingly small parts) I have to resort to the +2 ones.

Stairs and ladders 2 While struggling with something else I will be reporting on shortly, as a diversion at looked at the stairs and ladders again. I had fashioned the stairs from bakelite paper some three years ago (time is flying), but somehow I was not 100% happy with the result. The bakelite paper has a smooth surface and edge can be filed smooth too, but the glueing with CA was not quite so neat as I had wished. In principle it can be cleaned up well with a sharp chisel and fine steel-wool, but the inside edges of the steps are difficult to get to. Below is the result from that time: Selection of stairs (not yet trimmed to length) Having now the laser-cutter at my disposal, I decided to try my luck with it. The photo-etching templates I had drawn quite a while ago where modified for use on the laser-cutter. The idea was to build up the stringers from three layers of 0.15 mm thick Canson-paper. The innermost layer has slots for the steps. The steps themselves are build up from two layers of paper. Laser-cut pieces for stairs waiting to be assembled First the stringers were laminated together using lacquer and the edges sanded smooth, dito the steps. One stringer was then leaned against a little steel block with exactly square side on a glass plate. In this ‘jig’ the topmost and the bottom step were glued to the stringer with lacquer. Next the second stringer was glued on, while held exactly vertical with another little steel block. It was also checked that the step were at a right angle to the stringers. This assembly was let dry thoroughly. Still between the two steel blocks as ‘jib’ the remaining steps were slotted in and fixed with a drop of lacquer. Using the laser-cutting process ensured that the upper ends of the ladder had a uniformly rounded shape and the bottom was cut off at the correct angle to the deck. Collection of stairs and ladders (the stairs are 4 to 5 mm wide) The stairs were held in place (I assume) by shoes made from bronze. I cut out these shoes with the laser-cutter and attached them to the bottom end of the stringers. Eventually, they will be painted in bronze colour and glued to the deck. The colour of the Canson-paper soaked in lacquer comes close to that of teak, from which they were made presumably on the prototype. However, the actual colour depends on the number of layers of shellac I happend to apply and varied at places. So I will have to spray-paint them eventually to also get an uniform sheen on the surface. Assembly of ladders for the barbette The barbette is provided with two ladders, that allow the crew to scramble in and out of it, while for more leisurely access there is a narrow stair leading down from the bridge area. The stringers of the ladders, presumably steel on the prototype, were also cut from Canson-paper with holes for the rungs marked by the laser, which were opened up with a cutting reamer to exactly the right size for the wire to be used as rungs. Trimming flush the rungs of the ladders using a pair of cutting-tweezers After the trimming a second layer without perforations was laminated on. The ladders eventually will be painted white as the inside of the barbette will be. To be continued ....

This kind of sophisticated pantographs was used by cartographers in the old days, for instance, when they had to transfer the hand-drawn ordonance survey map originals onto the plates for printing. In fact, any time you needed a (technical) drawing for printing in a different size/scale you would have to re-draw it using a pantograph. Important point by Bob about transferring points, rather than lines. The same technique was/is used by sculptors, when they want to transfer their clay 'bozzetti' (the design model of the sculpture) onto a block of e.g. marble - but using a 3D-rig.

That's a very clever way of making the rivet heads in situ ! Did they just form by themselves by the heat, or did you use some sort of punch in addtion ? This rivet-making started my thinking, that one could make a head-former (die) as in real rivetting by shaping the hollow with a round burr in some brass rod. Using a piece of brass with appropriate holes as heat sink, one could mass-produce little styrene rivets in that way. Smaller rivets could be also made from stretched sprue or stretched styrene rods. Have to keep this idea in mind ...

My knowledge of the coconut trade is limited, but my understanding is that it is waste product from copra production. I didn't check, but I am rather surprised that the fibres should absorb so much water, given the fact that mooring and towing ropes are made from coconut fibres because such ropes float. Staining of cargo probably is not issue, as goods for sea-shipment would normally be sufficiently wrapped.

Well, Gustave Caillebotte became kind of a 'professional' in the area. He was successful in competitions, both on the Seine and off the coast. He designed his own boats, but hired a professional boat-builder and set up a yard to have them built. I don't think they used real silk sails on these boats, though Caillebotte might have had access to all sorts of fabrics, as his family's business was in fabrics. Sewn fabric sails are probably appropriate at this large scale. There is the silk that is used to cover the wings of model airplanes ('silk-span') or the fabrics used for silk-screen printing. This fabric is quite cheap actually. Not so easy to sew, but possible with a good machine. I have done it in the past with silk-paper backing to avoid distortion in the sewing-machine.

... these were supposed to be songs without word

In a German forum there is currently a discussion going on about classical draughtsmenship versus CAD. Somehow I have been leaning towards CAD early on, but have the feeling that certain elements would be quicker and easier using hand-tools - or perhaps I don't have the right CAD-tools. Still, there is this southing haptic experience of sitting at the drawing-board. I still have an A0-board that can be raised and tilted, together with the machine and all the draughting tools ... Will be watching this space !

Good start and the fairing sander is something I should make a mental note of. I seem to remember, I think from some magazine Article, that Bruno Orsel made a very elaborate metal framing device to produce the laminated frames. Reminded me of of the devices the Thonet factory used to make their bent-wood chairs (the 'classical' bistrot-chairs). I gather you will need a lot of clamps or something to keep the laminae bent in two directions, while settling.

In metal-working so-called 'engineers parallels' are used to raise work in a vice. These are either solid, ground steel-prisms or sort of short lengths of wavy steel sheets. They always come in pairs, ground to exactly the same height. There is also a height-adjustable variant, kind of two connected wedges. A cheap alternative are sections of drill-rod of different diameter and cut to the length of the vice. Drill-rod is ground to specific tolerances, so the diameter is constant, at least for our purposes. For narrow work-pieces use a single one, for wider work-pieces one in front of each vice-jaw. Yet another alternative are 'keys' that are used to 'key' say a gear-wheel onto a shaft. They come in a wide variety of sizes and are ground to certain tolerances, as they have to fit into the key-ways of given tolerances. As a mass-product the are quite cheap and I have pairs of different sizes for my miniature vices. As the jaws in the above vice are made interchangable, one can jaws of different height and perhaps different profile, say to clamp round work. Many engineers vices also have a rabbet cut into the edge of each jaw, so that thin, flat stock can be clamped without parallels.

There is a coloured drawing in the NMM, Greenwich, that shows the greenhouse arrangemnts in the great cabin. As I saw this in an exhibition in the 1970s, I don't remember though, whether it shows any skylights. I would search for BOUNTY on their Web-site.

As much as I admire McCaffery’s work, his insistence on using ‘permanent’ materials on about every second page in his book becomes tedious after a while. When it comes to the survival of artefacts, it is always a combination of factors and materials choices is but one of them. Storage conditions are of equal importance. Even brief periods of unsuitable conditions by accident can permanently damage a piece that has otherwise been kept under perfect conditions. Even changes from one set of conditions to another one, which both could be benign in themselves, can cause permanent damage. Most private homes do not offer the stable conditions one would find in the better museums.

Thanks again gentlemen ! Being myopic, there was a time, when I could just take off my glasses and didn't need to bother with any magnifying devices. Long gone. I am slowly moving on to stronger equipment. I have 2x magnifying safety glasses (which gives me together with my own 4.5 myopy a good magnification). Occassionally, I am using optivisors, but do not like them too much due to the short working distance. Some years ago I bought a set of magnifying telesopes as used by surgeons, but never really used them, because here the working distance is to large - they are meant to work standing over a patient, not for sitting at a work-bench. And then I got the stereo-microscope, which now that I adjusted it properly really like for working with the milling machine. It took the fear off of drilling 0.2 mm holes and you can properly watch what happens when milling tiny parts.

The good old 2nd Law of Thermodynamics gets us all and everything - sooner or later

There was a time, when I very much advocated, what Chapelle wrote and the requirements imposed in this respect by museums on the materials used in models they commissioned. However, there are practical limitations. Museums usually commission models at 1/48 or 1/50 and sometimes at 1/96 or 1/100 for larger, modern ships. So the ideas on materials to be used or not apply to those scales. If you are working in miniature scales and on more modern ships wood for instance is just not feasible, because you cannot cut it as thin as required. On could work with brass only and solder (lead-free of course), but this may also not practical for complex building units. So materials, such as styrene can be a practical alternative. So it is a trade-off between thicknesses of available materials, the surface texture, the workability and the long-term stability. In my current project I am trying to use long-term stable materials, but there are features, that just cannot be made with them (or my capabilities). I have models that made the half-way mark to 100 years and they show no visible deterioration. Some styrene may have become brittle, but as long as you handle it with care, it is ok. I even still use 'new' thin styrene sheet that I remember having bought in a London model shop in 1973 or so. I have seen intact samples of acrylic glass in museums that came of WW2 aircraft canopies. So, we do have 50 years more experience with these synthetic materials than Chapelle had. I think also, that acrylic paints will have quite a good survival rate, because acrylic molecules are quite stable. The pigment may be another question. As Bob said above, it may be a question of the original quality. I would trust in this respect more the manufacturers, who also or originally made paints for artists, than perhaps the ones that came more recently into the market and cater mainly for our community. Ok, everyone could cut corners, without the customer really knowing.

Wonderful work - but we don't expect anything less from this corner Without wanting to offend you in case it was hand-work, I hazard the guess that they were 3D-printed in wax and then cast in metal ?