Sazmodel GP7/9

Re: Sazmodel GP7/9

Postby Tom Dempsey » Thu May 22, 2014 9:34 pm

I purchased some of the Bone Valley hoppers and put them through the tests. Besides the fact that it seems virtually impossible to get a smooth enough surface to loose the layering, if you attempt to strip, the nylon goes away far faster than the paint. I just don't think it's a good process long term for a model and I agree with Bernd, cast resin is a far better way to go. Perhaps the lack of durability has to do with the term "rapid prototype", i.e., this technology is not meant to be used for anything of permanency. It is a great way to quickly build a three dimensional rough draft of your plan, and that is how it was originally explained to me.
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Re: Sazmodel GP7/9

Postby j p » Fri May 23, 2014 2:36 am

Tom Dempsey wrote:I purchased some of the Bone Valley hoppers and put them through the tests. Besides the fact that it seems virtually impossible to get a smooth enough surface to loose the layering, if you attempt to strip, the nylon goes away far faster than the paint. I just don't think it's a good process long term for a model and I agree with Bernd, cast resin is a far better way to go. Perhaps the lack of durability has to do with the term "rapid prototype", i.e., this technology is not meant to be used for anything of permanency. It is a great way to quickly build a three dimensional rough draft of your plan, and that is how it was originally explained to me.


The 3D print technology is perfect for small series, but the Shapeways material (and process) selected for TT models are not.
I have seen some some very nice 3D printed models made of metal by using the traditional lost wax technique. Lost wax is nothing new in TT scale. All those nice brass trucks from Kemtron were made by lost wax casting. The difference is that you can get the model printed in wax instead of making a mold for the wax casting.
Shapeways offer wax print + brass casting. It is just "slightly" more expensive and the 3D model should be adjusted for it in order to save the cost.

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Re: Sazmodel GP7/9

Postby CSD » Fri May 23, 2014 1:36 pm

MacG wrote:Is the project abandoned?


Yes. The materials are not up to a standard which I would consider making a product for sale. The finish is poor and the parts often arrive broken or malformed. Any minor improvement is not enough to make me consider this technology suitable for anything other than a prototype test. People deserve better.
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Re: Sazmodel GP7/9

Postby MacG » Fri May 23, 2014 2:40 pm

@CSD: pity, but perhaps it changes in some years with a improved und acceptable printing quality and materials

@Bernd: When I write about shapeways, I mean FUD, the best material for fine details. WSF is also better than prior years, but no comparing to FUD.

I would like to use the 3D-printed part as prototype for resin casting. Although I also accept 3D-printed parts as models. The lost wax casting is the best way to get a fine model. You can use it as prototype for resin casting, to lower the cost of a series.
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Re: Sazmodel GP7/9

Postby Marquette » Fri May 23, 2014 9:34 pm

Well, of course I'm not privy to the details but Lockheed has been using 3D printing in the F-35 project, and I've heard the RAF is using it for parts for their Tornado (or Typhoon?) fighters... so the tech /is/ there. The question is just, what is available to us peons?
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Re: Sazmodel GP7/9

Postby scaro » Sat May 24, 2014 4:04 am

Had this discussion before, I think, but i-materialise is substantially better. I got two prints of TT-ish (3mm) Western Australian ore hoppers as an experiment and they were good. Richard Stallard's blog shows his work in S scale :

http://i.materialise.com/shop/item/cab2 ... 4&Index=12

SW are the bargain basement option; it's not surprising they are not up to doing something like a GP7. They are like resin casting in the 70s-80s. You can and do get nice things but must expect to get five castings that are ultimately useless and get binned, in the process of finding one nice one.
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Re: Sazmodel GP7/9

Postby Marquette » Sat May 24, 2014 10:49 am

Good you mentioned that, Bernd, because it's true - and Shapeways uses the worst of the methods. I have a friend who is very into this and so I hear about it whether I want to or not...
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Re: Sazmodel GP7/9

Postby Richard-B » Sat May 24, 2014 2:35 pm

Marquette wrote:...Shapeways uses the worst of the methods. .

??? Shapeways uses multiple methods... for 3D-printing different materials on different machines, and according to their people I spoke with in San Francisco last week, will be adding more variations in the near future.

The main technologies we see today (and I emphasise - TODAY!) are:
FDM: Fused deposition modelling - the typical "3D filament printer" and some others
Rarely suitable for TT-scale items requiring any level of detail
SLS: Selective laser sintering - using granular plastic, ceramic, or semi-metallic material
Shapeways White Strong & Flexible (WSF) products that use this have the appearance of frozen sugar
MJM: Multijet Modeling (MJM) - liquid resin through a print head (like an ink-jet) and UV-cured
Shapeways Frosted Detail (FD) and Frosted Ultra Detail (FUD) are UV-cured acrylic polymer
SLA: Stereolithography (SLA) - laser cured photopolymer resin, pulled from a pool of material
The Form1 and XFab printers use this, and can achieve -very- fine surface detail and smoothness.

There are also much more expensive electron beam metal melting technologies...
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Re: Sazmodel GP7/9

Postby Marquette » Sat May 24, 2014 3:43 pm

I wasn't aware Shapeways uses SLA with photopolymers. My friend is very closely following the development of the Peachy (and Peachy Pro) printer, from what I've seen and heard this is the tech that will be the 'it' for modelling purposes.

Can one specify which method you want them to use for a job? I've not seen such an option...

I'd guess that electron beam is what Lockheed and the RAF are using?
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Re: Sazmodel GP7/9

Postby areibel » Sat May 24, 2014 4:10 pm

The only experience I have (besides Shapeways) is the GP38 master. It was the SLA cured resin. The detail is great, the finish is very nice as well. The only problem we had is the cured resin Mark used is a little brittle. Our caster had to do some minor repairs to a couple spots, luckily he was skilled and could do an invisible repair.
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