A little bit of Schoma does you good

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A little bit of Schoma does you good

Postby Jim F » Thu Jun 04, 2020 2:06 am

So - a different project that has reached a presentable stage but may yet get re-done.

I wanted a HOm tractor for Neuburg but the Bemo models of the Shoma Tm 2/2 are few and far between and pricey when they are available. Looking at the Brungger and Finkle DVD drawings and pictures, thought that it might make a workable 3D project so did some CAD and was quite pleased with the outcome.

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Found a supplier of a 12mm gauge tram chassis with 42mm wheelbase which was just 1mm short of the prototype so thought that would be quite acceptable. Got and modified that chassis for DCC by electrically seperating the motor and pick ups from the chassis and fitting a 6 pin socket. Also had to replace the whitemetal motor retaining strap with a brass strip to get a neat fit within the body.

chassis.jpg
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So - 3D print later and as I have found before, I simply cannot get a good enough finish to represent a metal surface without a lot of effort and loss of detail. I did however get a really good result with the chassis and handrails which I printed for ePLA - an engineering grade PLA that ends up closer in strength to ABS as you can anneal it in a domestic oven after printing to cure.

For the bodywork, I took a different approach and sliced the flat survaces into SVG files and used SWMBO Cricut Maker to cut these from styrene sheet and assemble like a plastic kit. Interesting bits with this - by using the cuts out for the windows as objects, was able to cut these as exact fit for the glazing in acetate sheet By using these as a template both adding and subtracting 0.5mm made window surrounds out of vinyl sheet, black front and rear, silver for the sides. Handrails are made from scrap bits of Sommerfeldt overhead wire - off cuts give up a useful amount of 0.4 and 0.5 mm wire! The front and rear handrails I snipped off the print and replaced with wire to get the rounded effect which had been lost in printing.

Managed to install SMD lights into the headlamps on the front and rear frames which are very effective. Installed a Micro speaker and am waiting for delivery of the Zimo sound chip with the correct project loaded from Germany.

Decals are not as good as I would like - but I know how to fix them! They are created from a mix of screen grabs of the actual loco and the nice set of original artwork files the kind people at RhB sent me with my license. Orange background on white decal paper - but the orange ended up very slightly off, I do now have the RGB match to the RAL code and a test re-print looks much better.

Its been a very interesting project combining materials and techniques. Learnt things and it could be improved. On another forum Paul S sparked an idea which I am going to try - might even make an infrastructure version if it works!

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Re: A little bit of Schoma does you good

Postby HJM » Thu Jun 04, 2020 6:21 am

Great stuff!

Those 3D printers sure come in handy, don't they? ;) :D
Cheers

HJ

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Re: A little bit of Schoma does you good

Postby Mike Thomas » Thu Jun 04, 2020 11:33 am

Very Nice!!
When I did my #93 project, I used the TL-modellbau RhB decals which are excellent, if a little pricey.
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Re: A little bit of Schoma does you good

Postby Jim F » Thu Jun 04, 2020 1:34 pm

I was pointed to that article and re-read it Mike - very nice job. The TL Modellbau is an interesting option mainly for the white print. I got a deal on a laser printer a while ago and really only use it for decals as the 1200dpi output and crisper image than the inkject makes a decent job of them. I have been toying with the idea of getting white toner powder and a blank cartridge but thats way down the to do list. May well go with the TL Modellbau suggestion as its not tooo bad a price and the postage quite reasonable as well.
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Re: A little bit of Schoma does you good

Postby Jim F » Mon Jun 08, 2020 3:35 am

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Re: A little bit of Schoma does you good

Postby Keith Yundt » Sat Jun 13, 2020 7:52 am

Looks and sounds great, Jim!
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Re: A little bit of Schoma does you good

Postby Jim F » Thu Nov 19, 2020 11:15 am

Revisiting this post - since I had done all the CAD work, seemed like a good idea to try it on my new resin printer. Very pleased with the result, whole job in a single print!

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Re: A little bit of Schoma does you good

Postby Glenn A » Fri Nov 20, 2020 6:27 am

I have the TL Decal sets 1714 and 1718, if you know which bits you want (especially the size as the white decals seem to be 3 different sizes) I could cut them off the sheet and post them to you. The sheet doesn't include the black decals for the data panel but that should be doable on an ordinary laser printer.
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Re: A little bit of Schoma does you good

Postby Mike Thomas » Fri Nov 20, 2020 7:52 am

Very impressive! The handrails have worked really well. How's the surface texture?
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Re: A little bit of Schoma does you good

Postby Jim F » Fri Nov 20, 2020 7:58 am

Glenn A wrote:I have the TL Decal sets 1714 and 1718, if you know which bits you want (especially the size as the white decals seem to be 3 different sizes) I could cut them off the sheet and post them to you.


That is very kind but following the comment way back by Mike Thomas - I went and ordered 1714 and 1717! I can do all the decals apart from white printed ones. I mentioned elsewhere that I got a non-commercial license to use the RhB loco on my models and with that the kind folk at RhB sent me a full set of digital files for their logo.

So - back to you - anything you need from 1717 - happy to do a swap :)
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Re: A little bit of Schoma does you good

Postby Jim F » Fri Nov 20, 2020 8:05 am

Mike Thomas wrote:Very impressive! The handrails have worked really well. How's the surface texture?


Surprisingly good! I have given it a coat of primer without any sanding other than removing the supports. The rear handrails proved to be rather fragile and snapped when cleaning up. Guess what - detached them from the CAD and printed a replacement set.

Bit more research and printed a second with slightly different settings which is even better. The learning point was to remove the supports after washing but before curing. At that point they snip of cleanly and as the material is still slightly flexible, does not snap. Then cure for 6 minutes and its done.

The high resolution of this printer with the 4K screen combined with the wash and cure machine is a bit of a revaluation to me.

Will post some more pictures as I progress.
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Re: A little bit of Schoma does you good

Postby Glenn A » Sat Nov 21, 2020 9:57 am

I'm in the process of repainting a push-pull Bernina set, the original had white RhB logos, I think I have enough CDS rub-down transfers in silver to do them, possibly enough white ones on the TL Decals sheets, my have to ask for one or two to complete the set.
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