wefalck

Loading crane Somehow I seem to move two steps forward and then one step back again. For one part completed there are several that jump off the table to be never found again or that are destroyed during subsequent steps of manipulation ... 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. The loading crane on the demonstration model in the former Naval Museum in Copenhagen The winding mechanism of the charging crane 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. Milling of the crane in the dividing apparatus Pulleys and forks form them are tiny parts machined on the lathe and the milling machine. Fork for the lower guiding pulley 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, big of a challenge, but at least I tilted the axis 20° when gashing it. Milling of the pinion and the cog-wheel Partly assembled loading crane The final assembly can only be done, once the crane-console has been attached to the carriage and the whole thing is painted. To be continued ...

That is really fast progress !

A difference of 0.3 mm between the arbor and the sawblade-bore makes it essentially useless. The blades should be a 'sliding fit' on the arbor. This is the problem with equipment bought in the USA/UK in Europe and vice versa. It should be possible, however, to buy sawblades with imperial dimensions in the UK. I have been dealing e.g. with RDG-Tools in the past: https://www.rdgtools.co.uk/ Otherwise, an arbor to DIN/ISO specifications for fits (h7, I believe) would be needed.

Seems that many of us are working in 'marginal' areas - havn't touched a rock for decades. But then I did my graduate studies in applied geology and a PhD in environmental geochemistry. Spent most of my professional life in waste and mining legacy management. Over the past ten years or I have been advising the EU as an academic and self-employed consultant on raw materials and mining waste management policies. I must admit that I don't know too much about riverboats, but always had a weak spot for them. Most of my knowledge comes out of Mark Twain's 'Life on the Mississippi'.

I think the straps are only about 1 mm in my measures, so not a lot of room. However, I noticed that on well-made and installed hinged the most visible part would be the screw-slot (assuming that we are talking about countersunk screws). So I was thinking that one could make a minute chisel and simulate the screw-slot with a light tap of this chisel ... Working in miniature, I always have this problem that features are really too small to reproduce, but one notices that they are not there, when left off ...

Thanks ! I am actually a Geologist ...

Your wife is a sedimentologist or hydraulics engineer ? I've tried to recreate a similar situation, albeit for a tidal harbour, using some real silt/mud, for a ship sitting on a 'grid', they had in some tidal harbour for iron ships:

Perhaps I should make an effort, but due to storage space restrictions the pictures taken in the later 1980s, I would have to check in my picture logs for the exact date, are stored in a rather unaccessable way at the moment. Not sure, when I would have time to dig them out for scanning ... Unfortunately, I think I never took pictures of the model.

Rocks or a sand-bank ? Only half-joking ...

Although Longridge's book has been written almost a hundred years ago, it still is a valuable source of information. He was able to draw on information before her preservation status and substance that has been lost in the fire a few years ago. The book also contains useful modelling hints and tips. The model he build is now in the Science Museum in London, but I don't know its actual whereabouts following the closure of their shipping department. I think anyone building a model of CUTTY SARK should have this book.

Daniele, what is fixture with the ball-bearings for ? To guide the plank during milling ?

No screws in the hinges ? 😮 ... just joking. Nicely done. Have to face that at some distance in the future too.

The release gear was not only used in an emergency, but any time the anchor was let go. The first step is to lower the bottom end of the anchor, so that it swings freely, suspended from the chain on the cat-head. That chain is shackled on one side to the cat-head and on the other side is put over a pivoting pin. How that works is best illustrated by a drawing in Longridges book; From: LONGRIDGE, C.N. (1933): The Cutty Sark.- 440 p., Kings Langley/Herts. (Model and Allied Publications, reprint 1975). In the above drawing the releasing lever is shown in the closed position. When it is pulled towards the viewer, the pin is free to rotate and the catting chain can slip off the pin. In the 1980s I took some pictures on board of CUTTY SARK and the mechanism looked exactly like that. Unfortunately, my slides are not accessible at the moment, so that I could not make a scan.

As always in life, there is never a simple answer to a simple question ? A laser-engraved deck cannot look really 'realistic' for a number of reasons: - the engraved line is likely to be too wide for technical reasons (but this depends on the scale of the model) - deck seems are filled-in with oakum and sealed with pitch because the deck planks expand and contract due to changes in humidity and temperature - when it is dry and cold, the seams are slightly depressed, when it is wet and warm, the seams slightly rise above the planks, because the latter expand - laser-cut decks are obviously cut from one sheet of (ply-)wood with one overall pattern of wood-grain, while in reality each plank has its own pattern; ideally the sheet would be cut from a wood with virtually no visible pattern of grain - ideally ... - the colour of each plank varies slightly, particularly, when not exessively holy-stoned. There would various strategies to make such deck look more 'realistic': - One could selectively stain each plank with very dilute stain in order to create this variability. - One could also first sand and seal such deck and then fill the engraved grooves with e.g. oil paint. After some drying time any excess oil paint can be scraped off; this would only work, when the engraved seams are not too wide. For any scale above 1:72 or so I would think that laying individual planks would be a more rewarding strategy. At smaller scales it may be still possible physically, but the wood grain may be too prominent, even after surface treatment.

Over the years I have come to dislike sawdust - seeing this slowly makes me reconsider ...

Thomas, I got into this from zero myself some 12 years ago, but stopped because of a house-move and other reasons. I had to figure it out the hard way with few suitable tutorials available at that time. On the other hand, I am a sort of chemist, so that side of the process did not challenge me too much and I understand what is happening (or not) and why. I think the key step for your success was to have the transparencies printed by professionals on high-resolution machines. It would be even better to go to a digital reprography company, where they expose repography films in a special camera, rather than melting toner onto the a transparent sheet. The repography process ensures 100% saturation and the resolution is probably an order of magnitude or more higher than even in professional laser-printers. I obtained my materials from a specialist supplier, including brass sheet already covered in photoresist. This takes out some key variables from the process, though cost more in terms of materials. But then the wastage may be less and it saves a lot of time. Still, I wasted a lot of material until I got all the parameters right, from the exposure times, to the concentrations of the solutions used, to the processing times, etc. Currently, I am actually rethinking the process, having acquired a small laser-cutter a few months ago. I will try to cover brass-sheet in black varnish and then burn the varnish away with the laser-cutter. This cuts out the step with preparing the masks. A technical problem to solve for double-sided etching is the poor zeroing behaviour of the cheap laser-cutter, which makes it difficult to achieve a good rapport when loading the second drawing into the cutter after flipping the sheet over.

I think it always looks good, when those surfaces that are machined in the prototype are also machined in a model. They just look crisper. Yep, iron in cast-iron would have the tendency to rust fast. Bronze in cast-iron has a good relative coefficient of friction and is less likely to get stuck. BTW, adding the lanyards to the percussion-locks would be a detail not often seen

I found that the only really critical step is making the masks, i.e. achieving a dense enough blackening. While this is not really a problem for people making circuit boards, it is a problem, when you want to push the technology to its physical limits, which is what we need to do in model building, at least for small-scale models. Neither laser-printed nor ink-jet-printed transparencies are really good enough. I also found that etching 0.1 mm brass or nickel-silver is not a problem, even up to 0.25 mm it works reasonably well, thicker sheets are difficult at least in trays. If you have cuvette with a percolator (air bubbling device), you may be able to push it a bit further. However, it is difficult to match the quality of professional foam- or spray-etched parts. One always battles with over- or under-etching in certain areas of the fret. However, I am talking here about exploring the technique in full, with surface-etching and having details as wide as the sheet-metal is thick.

Pat, I think the elevating screws were probably of bronze, as the thread is cut into the cast-iron barrel lug. Somehow I had been thinking of the other version, where the barrel rests on top of the screw and there is a separate nut. Thinking 3D-printing further: one could actually print some holding fixtures to exactly match gun barrels to hold them e.g. in the lathe for machining say the bore.

Sorry, I was on the wrong planet, somehow I did not read the first post carefully and was thinking of the fairleads for running rigging that are lashed to the shrouds ...

I would say, it depends on the scale. In most scales the lashing would be oversized anyway, so it is better to hide the ends, rather then using an oversize knot. On the real thing, I would suspect that it was finished with a couple of half-hitches around the shroud, but I actually don't know.

There is a lot of loose gear in a whaleboat and it may have to rowed for hours in a heavy sea. So it is a good idea to secure with lanyards those things that are vital to the purpose, namely the hunting gear. Securing the lances with a slip-knot to the boat might be useful.

I am very much impressed by those guns, Pat. They came out really nicely. It shows the potential of 3D-printing in all kinds of shipmodelling. You also did a good job in picking out in colour the details, such as the percussion lock. What also struck me immediately, was the 'real' elevating screw. Nice detail ! I gather it is 1 mm threaded brass rod or something like that ? Where they and the wing-nut made from bronze in reality ? Can you remind me, which 3D-printing technique you are using and what material ? Small-scale shipmodellers tend to make finished parts with with technique, while I am thinking of it more as a technique to reproduce parts that in the real world would have been cast in iron or bronze. The moulds would have been made from wood with complicated shapes that are not so easy to reproduce in small scale and even more difficult to reproduce, if you need several identical parts. Such parts then would still need finishing off on the lathe or mill, jut as for the prototype. However, the material used for filament-printing does not machine very well. One observation (if it is not too late): the axles seem to be rather long, the cotter pin should be very close to the truck, so close that it can spin freely, but does not move sideways on the axle. Not sure, I mentioned this before, but I tend to 'burnish' parts painted in metal paints with soft pencils. The graphite gives a metallic sheen to them. This could be good on the tyres of the trucks, but could also create even more plasticity on the lock.

Well, if the planks are too thin, this effect can occur as well, when they are bent across quickly changing radii. The best solution would be to fill the spaces between the bulkheads and then fair again the whole thing.

Run a soft pencil (B6-B8) between the teeth of the gear, it will make the silver paint look more like metal !