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S.M.S. WESPE Armoured Gunboat (1876) of the Imperial German Navy by wefalck – 1/160 scale, when first commissioned

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Thanks, gentlemen !

 

Indeed, the technique is quite similar to facetting gem-stones, but there one uses abrasive discs 'charged' with abrasive or polishing powders. I thought of using silikone polishing bit, but they can round the edges of Plexiglas. I do have small polishing discs in brass, but don't have diamantine to charge the discs. Perhaps should look into this, as these hard discs don't round the edges, when polishing. However, diamantine is a bit messy and not so good for the machines ...

 

Yep, the brass columns will be painted to simulate the varnished mahagony. I found virtually all real wood too coarse in grain, even boxwood, at this scale. Also turning such delicate parts with the necessary definition is very difficult. One cannot stabilise the boxwood with CA before turning, because it has to be dyed afterwards. So it will have to be paint. I still have to experiment a bit to find a satisfactory procedure to simulate the varnished mahagony. It will be probably a base coat in a light wood colour with several washes of mahagony-brown to create depth. Then a final clear semi-gloss varnish, again to create the depth one finds on polished wood. I am talking about using acrylics here. The same technique will be used on the skylights, stairs etc. that would have been varnished mahagony or teak at this time.

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On 11/4/2019 at 1:12 AM, wefalck said:

Indeed, the technique is quite similar to facetting gem-stones, but there one uses abrasive discs 'charged' with abrasive or polishing powders. I thought of using silikone polishing bit, but they can round the edges of Plexiglas. I do have small polishing discs in brass, but don't have diamantine to charge the discs. Perhaps should look into this, as these hard discs don't round the edges, when polishing. However, diamantine is a bit messy and not so good for the machines ...

Would toothpaste or some sort of household scouring powder work? Not sure. Just wondering.

 

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Yes and no. With softer abrasives, one needs to also a softer material as a carrier, such as wood. Watchmakers use, for instance, boxwood discs charged with chalk, rouge (iron oxide) etc. for polishing.

 

I found that a new and unused milling cutter moved at slow speed gave a quite polished surface, at least on the tiny surfaces we are talking about.

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5 hours ago, wefalck said:

Yes and no. With softer abrasives, one needs to also a softer material as a carrier, such as wood. Watchmakers use, for instance, boxwood discs charged with chalk, rouge (iron oxide) etc. for polishing.

 

I found that a new and unused milling cutter moved at slow speed gave a quite polished surface, at least on the tiny surfaces we are talking about.

Interesting. I never knew about needing to match the hardness of the carrier to the hardness of the abrasive. They look great as they are, of course. There's really no need to be obsessive about it! :D 

 

I love your watchmaker's mill, by the way. I envy your great collection of fine tools! I'm sure there's a great story to go with every one of them.

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Carrier hardness vs. hardness of the abrasive vs. hardness of the material to be worked on is actually very important. If the carrier is too hard, the abrasive gets squashed and becomes ineffective, if the carrier is too soft, the material may smear over the abrasive, rendering it ineffective. This is why we have relatively soft abrasive wheels with red iron-oxide as binder and the grey ones with harder Si-carbide as binders. Soft polishing pastes (say 'rouge' in oil) would smear around a steel lap and not do anything. An old-time watchmakers polishing kit would contain lapping disc made from steel, bronze (bell-metal), and boxwood.

 

A little anecdote: as a student I worked in the institute for tunnel engineering of the ETH in Zürich (Switzerland); my job was to prepare samples for testing different pre-cutting configurations for tunnel-boring machines. For this I had to drill large cores (150 mm diameter) from different rock types, ranging from granite to sandstone. We had a large drill-press and a core-drill with a diamond-impregnated rim. I was really struggling with some of the granites and we thought something was wrong with the core-drill. So I took it back to the distributor; he chucked it up in his concrete-drilling machine and went through a slab of high-quality concrete (from a nuclear power station) like butter. He explained to me that we just got a drill with the wrong binder (brass) and that it smeared over the diamond grains, when drilling in very hard rock, such as granite. 

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18 hours ago, wefalck said:

Soft polishing pastes (say 'rouge' in oil) would smear around a steel lap and not do anything.

Well, that explains a lot! For all these years, I've simply tested each abrasive stick in my collection until I found one that worked best for polishing a given item. There never seemed to be much rhyme or reason to why one would work well on any particular piece I was polishing. Now it makes sense. I definitely have experienced jeweler's rouge smearing around and doing little on stainless steel !  I learn something new every day. Thanks for the tip! :D 

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Hello Wefalck,

 

I've been reading your log from the beginning and have just caught up.  A very interesting and educational thread to be sure.  Your machine tools are great but it is your skill in using them that is so admirable.  Astonishing detail at so small a scale.  Very impressive and beautiful work!  I look forward to future updates.

 

But . . . . . are you sure that match stick isn't really a modified broom handle with a sponge stuck on the end? 

 

Gary

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Thank you to you both for your kind words. Unfortunately, the path is not so straight. Which is, in addition to frequent interruptions due to business travels, a reason for the long intervals between postings ...

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19 hours ago, wefalck said:

Unfortunately, the path is not so straight.

The real world tends to intrude rudely. I'm merely following along and I'm not in a rush - this is your leisure time! Again, thanks for sharing!

 

Regarding your machine tools, I love there is a domain in machining/metal work where no one complains about the small size of their equipment. :)

I believe you mentioned being drawn to the challenge of small-scale modelling (and the ease of storage/display).
I'm curious: what drew you to machining in such a small scale? Have you always worked at such small scale?

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Well, that's a difficult thing to say. I gather, I have always been drawn to intricate things, in museums to the small highly-detailed models. Of course, I admired the big (board-room) models with their metal-work etc., but knew that I would have never the space for such a project - I hate giving away models, so I need to find the space to keep them. My first ('semi-scratch') model was in a 1:60 scale and then I continued in the same scale with the following scratch-built project. Then I realised that this was an unusual scale - it would have been better to go for 1:72 or something like that. Large scales, of course, are much more impressive for the casual observers.

 

At some stage, I decided to go for scales in which figurines from the railway-community would be available, here on the European continent these are 1:87 (HO-scale) and 1:160 (N-scale), HO-scale for small boats and N-scale for larger vessels. The kind of limiting criterion was, that the overall drawing should fit onto an A4-sized paper.

 

The challenge at these scales is not so much the machining as such (large-scale models could have also very small and intricate parts), but the availability of suitable raw materials. There is a limit down to which you can get wires, sheet-metal or -plastic or paper, or threads for making ropes. Sometimes also it would be geometrically possible to machine the parts, but the material just becomes to flimsy at small dimensions.

 

Of course, it would be nice to also have larger machines - particularly for making attachments for the smaller machines ;)  However, my 'carreer' involved moving every few years, so I decided to keep my workshop mobile in the sense that the machines can be easily dismantled and crated or packed. The smaller watchmakers lathes come in fitted boxes anyway and for the milling machines I made solid crates.

 

The appartment we will be retiring to in a few years time hopefully will have dedicated (small) workshop cum display room, but somehow my wife still tries to convince me that I won't really need it, as we would be out in street-cafés anyway, as the locals do in southern Europe ...

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Thank you very much for the kind words !

********************************************

There are some really delicate parts lined up now, such as the frames for the freeing ports along the bulwarks. My original thought was to have them photoetched from 0.1 mm brass. However, given the difficulties I had in creating good, dense etching masks, I thought of trying a different route and something that is less messy. Laser-cutting seemed to be an interesting proposition.

So I got myself a new little toy at 100€ incl. shipping. Toy is perhaps an adequate description for these small compact machines that are now on the market. Their design-purpose probably is to mark merchandise with a burnt-in logo etc. For this reason they are mobile, so items of any size can be marked by just putting the little (15 cm x 15 cm x 15 cm) box on them. Their power is limited, 3W. A mechanical resolution of 0.05 mm is claimed, with a diameter of the laser-spot of 0.1 mm. The engraving area is 53 mm by 53 mm. The software driver works by converting the images into bit-maps and then it runs them down line by line. I should try to find another driver that uses vector graphics, which would speed up the cutting process presumably.

https://www.maritima-et-mechanika.org/maritime/models/wespemodel/KKMoon-Lasercutter.jpg

KKMoon-Lasercutter with a 3W laserdiode

 

The software allows to adjust various parameters, including the contrast of the image, the power output of the LED, and something called ‘cutting depth’, though it is not clear what the latter really does. The focus of the LED can be adjusted manually to allow for materials of different thickness, but it is difficult to judge, whether really the minimum of the spot-size has been achieved.

Given the power of only 3W, there are limitation to what materials can be worked with. The cutting resp. engraving effect depends on how much energy is needed to burn or vaporise the material. Paper works well, but a 0.4 mm cardboard seems to be the limit. I did not have much success with white styrene, only some light surface marks resulted even at the highest settings. Hard paper (phenolic resin impregnated paper) would have been my favourite material, but apart from the strong smell (the fumes are also not terribly healthy) a 0.2 mm thick sheet was only cut half-way through. Semi-transparent tracing paper does not take up enough of the energy and remains untouched. A sufficient optical density is required in order to absorb the energy and burn/evaporate the material. Strangely enough, the laser left quite visible marks on the piece of roof-slate that I used as fire-proof protection under machine.

Converting a drawing into a cut-out piece is not quite straightforward. I first had to work out a way to scale the bit-map and JPEG images that I created from my CAD-drawings. The solution was to draw a box around the graphics to be exported, measure this box and then to scale the exported drawing in Adobe Photoshop to a number of pixels the resulted in the box of being of the desired size when laser-cut. The resulting scaling factor was 1 mm = 20 pixel, which was indeed the claimed resolution of 0.05 mm.

On an image everything that is black will be burned away and everything white will remain. However, simply converting the CAD-drawings into images resulted in too narrow/small parts due to the fact, that the each burnt point has a diameter of at least 0.1 mm. Therefore, it was necessary to adjust the sizes of the areas to be burned away so that the remaining parts have the desired dimensions. The effect depends on the burning parameters and on the material. So, unfortunately, each new material and new part will require a certain amount of trial and error.

I tried my luck on another set of very delicate parts, namely the steering-wheels. They have an OD of just under 12 mm. Turning the complex shape of spokes of 6 mm length appeared to be daunting task, even if one could have perhaps made the handles and the spokes themselves in two parts. The laser-cut ones look quite good after a few trial runs, but I have to see, whether I can build up enough thickness from several layers. Cutting them from 0.4 mm thick cardboard was not fully successful.

wespe-progress-227.jpg

Laser-cut steering wheels of 12 mm outer diameter

 

I just wanted to share the first experiences with this new workshop toy and trials will continue.

 

 

To be continued soon(?) ...

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As per your usual, very lovely and crisp details, especially at the scale you work

 

Interesting mobile laser cutter. Concerning the vector driver, does the cutter support the required software? For just the driver might just not be sufficient to get it working with vector graphics. Keep us informed on your findings please

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Way back in the early 1980s I used to program in BASIC, including driving a plotter. However, I think, technology has moved on since and didn't quite keep up with it :stunned:  From what I read diagonally, it should be possible to drive the laser-cutter from vector graphics, but for the moment, I don't really want to get into technology development. Producing parts is the call of the day, in order to get the SMS WESPE project finished - I have been on it now for 13 years, believe it or not ... I have been too often side-tracked by making tools.

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Eberhard - interesting. I will be pleased to see how you get on.

20 hours ago, wefalck said:

Their design-purpose probably is to mark merchandise with a burnt-in logo etc

I suppose the days of an ink pad and stamp are over. Isn't technology wonderful.

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Nice 'toy' and very acceptable results Eberhard.  Quite an interesting concept for producing very small wood partss.

 

cheers

 

Pat

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4 hours ago, KeithAug said:

I suppose the days of an ink pad and stamp are over. Isn't technology wonderful.

It can be, however, we loose more and more knowledge on the use of so called "craftmanship"

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Eberhard,

3W isn't much power especially for cutting.  It's probably designed for just what's been mentioned.. engraving a bit of cardstock or wood. The advantage of vector drawings for laser is that cuts from end point-to-end point and not a series of dots.  

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Of course it is wonderful to watch a skilful craftsman at work and a job well executed probably gives these craftsmen great job-satisfaction. However, what counts in the real world is the quality of the result, how much time is needed to arrive there and how much it costs. Modern technology allows us to produce intricate parts that would be very difficult, if not impossible to make with traditional tools and methods. Perhaps I could have made these steering-wheels as a sandwich of five or ten on my filing machine, but even the finest and smallest commercially available files (and I have these) may have been to coarse. My original intention was to use photoetching, but this is always a very complex procedure, when you cannot have it set up permanently somewhere - not really an ad hoc useable tool. Perhaps CNC-milling would be an alternative too, but here you always have the problem of rounded corners due to the practical limitations of tool size, which is probably 0.3 mm diameter, compared to the 0.1 mm for the laser-point.

I was aware of the limitations of this lasercutter before I made the decision to go for it. Unfortunately, I don't have the space for a bigger and more powerful machine.

Apart from the cutting-speed, I am not so sure that tracing a vector-drawing gives really a better end-result. The slightly jagged edges would more or less remain due to the motion of the stepper-motors. They might become somewhat more smoothed out though due to the fact that the laser would remain powered during the movement. As the laser-dot is twice the size of the steps, a certain smoothing already occurs.

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