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wefalck

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About wefalck

  • Birthday 05/01/1956

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  • Website URL
    http://www.maritima-et-mechanika.org

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  • Gender
    Male
  • Location
    Paris, France
  • Interests
    19th shipbuilding and naval history, indigeneous boats and their history

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  1. Acrylic paint vs acrylic ink

    Well, you partly answered yourself your question: the key point is particle size or rather the absence of particles. For this it is important to recall the difference between the different media: Paint essentially is a suspension of pigment particles in a solvent and film-formers; the objective is to create a covering layer of paint made up from the pigments and the film-formers; in the case of acrylic paints, the acrylic monomers will also undergo some sort of chemical reaction, by which they cross-link to form a layer into which the pigment particles are embedded. Dyes are molecules dissolved in a solvent; the dyes either adsorbe to the surface of the material or may undergo also some chemical reaction with the material to be dyed; in consequence, they do not form a continuous layer on the surface of the materials. Inks can be either paints or dyes; in the former case they are called pigmented inks; acrylic inks fall into this category; like paints they form a more or less continuous layer on the paintes surface albeit their particle size is much smaller than in paints, allowing them to be used with e.g. pens. Simulating the tarring etc. of ropes presumably can be done with inks, as on the prototype the tar only partially penetrated and part of if acted as a dye and part of it as a paint. Paints on the other hand would stay on the surface and form a layer. I gather paints could be used to simulate the tarring with coal-tar of later periods, but would be less suitable to simulate applications of wood- (Stockholm-)tar.
  2. The separator is a good idea - it is easier to search through a small pile of debris than across the whole workbench (which unlikely is as clean as in a clean-room ). I gather the rentention capacity would depend on its length, so a long, narrow jar might be safer than a shallow one, or you would need to put a bit of foam in front of the internal suction pipe.
  3. Dumas Barrelback engine

    I have not been suggesting that a 1/72 or 1/48 scale resin model would be the solution for your problem.
  4. Dumas Barrelback engine

    If you have CAD-program and the skills to go with it, you could develop a virtual 3D-Model and have it printed ... trawling the 3D-printing companies, such as Shapeways, might also be worthwhile. Wasn't there even a Chris Craft with an egine here on the forum, or was this a Riva ? I have been tossing with the idea of a model of an early run-about or speedboat with one of those huge marinised surplus aero-engines that they used in the 1920s or so. There various WWI resin engines in 1/72 and 1/48 scale available.
  5. Bench Vise

    One probably needs several sizes of vise ... the best small bench vises are those for jewellers/clockmakers, but they can be very expensive, even second hand. Brands are Bergeon, Leinen or Boley over here in Europe. It is a good idea to have one that can be turned. For precision work a jaw width of 40 to max. 60 mm seems a good size. If you cannot buy one of the above brand ones, it is always a good idea to check the one you intend to buy, whether the jaw close neatly and parallel. There is a lot of cast-iron scrap being flogged to undiscerning customers. For really small work, you might also want to look at so-called toomakers insert vises. They come as small as 25 mm jaw-width and are (usually) very precise (at only around 35€). They are mainly used in EDM-machining, but come hand for other purposes. You can use them on the bench, but may have find a way to fix it to the bench - they have normally two M4 threaded holes at the bottom.
  6. I kind of suffer from the same disease: not enough space ... one soution I decided upon some time ago was to tackle only projects that can be drawn on an A4-sheet ... for bigger projects I would scan the plans and correct them for distortions as mentioned above. You then can print out (again checking for distortions) as many working copies as you need. For individual parts I usually print them out even at a magnification (say 10x) and add measurements by hand. This allows you to correct for additive errors due to line thicknesses etc. The overall part has to have the correct size and you can correct your measurements to fit into the overall size. In other words, you arrive at a sort of graphical cooking-book from which to work. I have either the sheet flying around my work-table or fix it to light-weight clip-board.
  7. Angle of ship masts

    A displacement hull driven by sails cannot go beyond the theoretical hull speed you mentioned, raked mast or not. Sails just cannot supply enough energy in order to overcome the cavitation effects at the end of the hull that would develop. Before towing-canals and the theoretical foundation (e.g. Froude) were developed, ship designers experimented by feel and looking for examples in nature. As you noted, it is the combination of design and implementation parameters that determine, whether a given ship is fast or not. Changing this combination by trim, for instance, can change the performance rapidly. However, as I said before, raking masts can make a particular ship faster, but not necessarily so - but it certainly makes it look faster, which can be important in both, a naval and a commercial context. A fast looking ship is likely to attract more business. This is why the ocean-liners of old were given raking funnels. At a time when ship designers experimented with waterlines, where the main breadth was above the middle, i.e. that had very sharp, even hollow lines forward, raking the mast may have brought the centre of gravity of the sail plan closer to the centre of gravity of the body plan, thus reducing the tendency to dig in. The same could have been achieved by stepping the mast further aft, but then the mast would have come to close together, partially blanketting each other. When in the later 1850s the hulls became longer and the sharpness more evenly distributed between the forward and rear section, the need for raking masts disappeared. One should also distinguish between naval and commercial practices. Commercial ships need to be able to maintain a steady speed across all weather conditions in order to achieve short travel times, i.e. the average speed is important, while for naval ships often the top speed is the important criterion.
  8. Power versus Hand Tools?

    I tend to think that it also depends on the type of ship you are building. Pre-industrial ships were built without any machinery and everything was shaped by hand - this can be reproduced by hand-work (apart perhaps for the tedium of sawing timber to size). Industrial-age ships increasingly tend to have geometrically well defined parts, which would have been produced using machinery, which in turn are easier to reproduce using also machinery. It is also a question of the scale you are working in. Bigger parts are easier to handle manually than small parts that may require only minimal amounts of material to be removed, which is easier to do with the controls of lathe or milling machine.
  9. Angle of ship masts

    Mast rake is also a matter of fashion as the centre of gravity of the sailplan can also moved aft during the design or building phase, thus moving aft the fulcrum that acts on the hull and makes it dive into the sea. It is noticeable that a pronounced rake was fashionable from around the mid-1830s to about the mid 1850s. The 'true' clippers of the late 1840s to late 1850s, though having comparatively little bouyancy forward, mostly did not have very raked masts. The rake seems to have been also more pronounced on schooners and some brigs than on barques and full-rigged ships.
  10. This topic has been discussed already several times on this forum and I apologise for posting again the two pictures below that show what the coppering really looks like (albeit reconstructed): DON FERNANDO II E GLÓRIA (1843) in Lisbon Two observations: - plates overlap top-down and fore-aft, meaning that the process started at the keel and worked upward, and back to forward - the nailing causes depression - there are no protruding nail-heads; the reason is that the plates were fastened on a layer of felt soaked in tar. Assuming that they are pressed/stamped, you can improve those plates from the kit by gently rubbing them on the side with the protrusions with a piece of round hardwood on a cutting mat. This pushes the protrusions back and leaves slight dimples. One has to play a bit with the amount rubbing and the pressure applied. They are then to be fastened with the side that showed the protrusions inside, i.e. the other way around from what most people would do. Incidentally, the copper-green colour, as shown on the second picture, only appears when the ship is in dry-dock for prolonged periods. The 'service colour' is a dull copper-brown, as on the first picture.
  11. I tend to think that in a well-done glue-joint the glue does act more like a tenon between the two pieces of wood; it sort of keys into the surface roughness, while the high points touch. The glue should not form a separate layer between the pieces, as if you were glueing say two pieces of platic with a contact cement.
  12. These blackening agents rely on redox reactions by which either copper carbonate (CuCO3), magnetite (Fe3O4), or selenium oxide (SeO2) are deposited on the metal surface. This would require a electrochemically less stable metal in the alloy. Whether it works for a given alloy probably depends on how much say copper is contained in it.
  13. I have never been entirely happy with the precision of mitre-boxes, regardless of their size. It is quite tricky to have the right thickness of the saw, thick enough to not wobble in the slots and thin enough to not get stuck. A micro-mitre saw as described in the previous post might be, indeed, a good idea. Perhaps one could also construct one on the basis of the Xacto-sawblades.
  14. Them Old Jokes

    A man comes to the vet with a huge Dane: Doktor, the dog chases little cars and I can't get him away from it ! Vet: But all dogs do that, what's the problem ? Man: Well, he catches them and buries them in the garden !
  15. Them Old Jokes

    Drove one of them in mid-winter in Lappland - I don't dare to imagine what would have happened, if a reindeer would have jumped in front of the car ...

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