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Post by wdiannes on Jan 31, 2014 11:55:16 GMT
Has anyone been using 3D prints as foundry patterns?
I have been printing the parts for my project in ABS and have been thinking about the best way to prepare them.
I was thinking about painting them with ABS adhesive to seal any tiny voids in the plastic and make sure the print layers are well bonded.
Over that, I would apply a layer of thick paint to smooth the surfaces so the foundry sand doesn't stick.
Anybody out there with experience?
Thanks!
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Post by Rex Hanman on Jan 31, 2014 12:17:59 GMT
I'm sure that will work well but make sure the paint is totally dry or the sand will stick and mar the surface. I was thinking about painting them with ABS adhesive to seal any tiny voids in the plastic and make sure the print layers are well bonded. Over that, I would apply a layer of thick paint to smooth the surfaces so the foundry sand doesn't stick I have before now made patterns from Jelutong, and later MDF, and then vacuum formed a thin layer of plastic sheet over it. This left a very smooth and durable surface that resulted in great castings. I didn't have to wait for the paint to dry either.  |
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r707
Active Member
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Post by r707 on Jan 31, 2014 20:49:58 GMT
Hey guys - 3D printing patterns has become increasingly popular in ME circles particularly over the past few years as printing costs have continued to decrease. For some time I've been assisting others in 3D modelling & 3D printing patterns - I've attached a link to some recent images of a project for a 5' g loco under construction in Australia - simple single-sided patterns 3D printed in sandstone material before being sandcast in bronze at a foundry in Sydney; plus.google.com/u/0/photos/103018036322100048031/albums/5847787849751668401/5975147833562533682?sort=1&pid=5975147833562533682&oid=103018036322100048031I'm actually an expat Aussie myself, now working in the Netherlands for a 3D printing company called Shapeways - (www.shapeways.com) so I have access to a number of resources and 3D printing materials incl. sandstone, nylon 12, resin, laser sintered stainless steel, and also pure brass/bronze (3D wax printed patterns then Lost Wax cast). I've printed patterns from small axle box covers in ultra high detail resin - to large patterns (250 x 100 x 75mm) for LW casting in mild steel. There is another member of this forum, Abby - who has quite an elaborate LW casting setup, and has been using 3D prints for patterns for some time. He will no doubt have a lot of advice if you're keen to pursue this further. kind regards, ~ Phil |
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Post by Deleted on Jan 31, 2014 21:02:51 GMT
I'm sure that will work well but make sure the paint is totally dry or the sand will stick and mar the surface. I was thinking about painting them with ABS adhesive to seal any tiny voids in the plastic and make sure the print layers are well bonded. Over that, I would apply a layer of thick paint to smooth the surfaces so the foundry sand doesn't stick I have before now made patterns from Jelutong, and later MDF, and then vacuum formed a thin layer of plastic sheet over it. This left a very smooth and durable surface that resulted in great castings. I didn't have to wait for the paint to dry either. Ah yes Jelutong a lovely wood to carve, grain free and perfect for patterns, I've worked with it many times over the years although today we use chemi-wood which is a resin board perfect for carving and doesn't need sealing to paint and machines very nicely. I use Axon products, iirc the best board for machine work was prolab 65 which is the hardest but cuts like butter on a machine, there's two others 45 and 55 which are less dense, not good for machining but very easy to hand carve. regards Pete |
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Post by wdiannes on Feb 1, 2014 0:19:49 GMT
He will no doubt have a lot of advice if you're keen to pursue this further. ~ Phil For sure! I hope to take my patters to the foundry on Monday to find out their preferences and whether sand cast is the way to go or if they can do lost wax (lost plastic?) for similar price. |
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jma1009
Elder Statesman
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Post by jma1009 on Feb 1, 2014 0:42:36 GMT
ive a 5"g loco i want to build that i will have to make the wheel patterns for, so in the light of the above very interesting discussion what is the ideal material to make the patterns from? im a bit of a dab hand at woodwork and carving etc and made patterns for my first loco some 30 years ago!
cheers,
julian
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Post by Roger on Feb 1, 2014 8:09:52 GMT
I was chatting to a guy at the Alexandra Palace Exhibition who used 3D printed patterns for the lost wax steel string hangers on his prototype gas turbine locomotive. The finish accurately reproduced all of the fine bolt head details and all of the layer marks in the 3D pattern too. He was using ABS for the printing, but he had used others too with similar results. I don't think it matters much what you print with, it's the finish that's more of an issue.
Roger
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Post by ejparrott on Feb 1, 2014 9:19:04 GMT
ive a 5"g loco i want to build that i will have to make the wheel patterns for, so in the light of the above very interesting discussion what is the ideal material to make the patterns from? im a bit of a dab hand at woodwork and carving etc and made patterns for my first loco some 30 years ago! cheers, julian David might be watching...he's contemplating options for not buying wheel castings for his 9F... Jelutong is a very nice wood to do fine work with as Pete says. Depends a bit on how many castings you want to take from it. I'm making metal patterns for my engine. |
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Post by cplmickey on Feb 1, 2014 11:04:40 GMT
Going back to the original post - I had a wheel pattern 3D printed in the ABS. It was fantastic but I was concerned about it getting damaged at the foundry as it doen't seem overly strong so I made a silicone mould of it and then used casting resin to produce the pattern. I needed 20 wheels so the pattern was going to see quite a bit of use. Maybe I was overly cautious but I've still got the original pattern in perfect condition and it only cost about £20 to make the resin pattern.
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Post by Roger on Feb 1, 2014 12:01:02 GMT
Going back to the original post - I had a wheel pattern 3D printed in the ABS. It was fantastic but I was concerned about it getting damaged at the foundry as it doen't seem overly strong so I made a silicone mould of it and then used casting resin to produce the pattern. I needed 20 wheels so the pattern was going to see quite a bit of use. Maybe I was overly cautious but I've still got the original pattern in perfect condition and it only cost about £20 to make the resin pattern. I think the guy I mentioned said that the foundry made a silicone mould and cast the wax in that. There was another 3D printing machine I saw a couple of years ago that made very robust parts but the resolution at that time was dire. Sadly I can't remember the company so I don't know if things are better now. |
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44767
Statesman
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Post by 44767 on Feb 2, 2014 4:46:25 GMT
You could use the rubber mould to make several resin patterns and mount them all on the same board. This will lessen the abuse given at the foundry and make it cheaper to produce as the cost of a casting is more in making the mould than it is the material cost.
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44767
Statesman
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Post by 44767 on Feb 2, 2014 5:00:15 GMT
I was chatting to a guy at the Alexandra Palace Exhibition who used 3D printed patterns for the lost wax steel string hangers on his prototype gas turbine locomotive. The finish accurately reproduced all of the fine bolt head details and all of the layer marks in the 3D pattern too. He was using ABS for the printing, but he had used others too with similar results. I don't think it matters much what you print with, it's the finish that's more of an issue. Roger There is a huge range of materials for producing RP's. ABS is probably one of the cheapest but it is also coarse compared with the likes of Shapeway's ultra high detail. Some of you have seen this. It was printed by Shapeways, had a rubber mould made from it and lost wax cast in silicon bronze. Yes there are some striations but the background is tapestry to give you the scale!  By the way, lost plastic doesn't work very well; the plastic doesn't melt away or burn out completely, comprimising the quality of the casting. Mike |
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Post by cplmickey on Feb 2, 2014 21:28:23 GMT
I suppose it depends what you want it for. Shapeways made mine - they call it white nylon, I just assumed it was ABS - but it was fine for wheel castings using sand casting methods. Still cost me £170 though.
The quality on your cover is excellent - what was the original material it was printed in?
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r707
Active Member
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Post by r707 on Feb 3, 2014 8:08:46 GMT
Hey guys, Without wishing to speak for Mike - The pattern for the axlebox cover is made from a translaucent resin generically called FUD (frosted ultra detail), with each layer printed and cured with UV light. This process is perfect for capturing very small details with the HO / N scale community in particular capitalising on this material to produce their own highly customised models. You can see some examples I've done in this material here; plus.google.com/u/0/photos?pid=5976078355203447026&oid=103018036322100048031- with the concentric rings indicating the build layers (0.05mm thick), the apparent surface roughness exaggerated by the light picking up each 'leading edge' on the convex face of the axlebox cover. This material is more expensive than laster sintered nylon - but is perfect for producing high-detail lost wax castings - as Mike as shown above. Cheers Phil |
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ennech
Active Member
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Post by ennech on Feb 17, 2014 16:21:40 GMT
I have used 3D printed patterns but it depends on the size of the item as it is cheaper on larger stuff to CNC machine a pattern out of HD Polyurethane Foam. The lister Nameplate in brass is 2" square and started out as a 3D print from which a latex mould was made to produce lost wax castings in brass. The insert in the piston corebox is a 3D printed part, untreated. The loco wheels which are 8" diameter were produced from CNC patterns, so it is "horses for courses" www.flickr.com/photos/117856753@N02/ |
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ennech
Active Member
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Post by ennech on Feb 20, 2014 12:49:15 GMT
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uuu
Elder Statesman
your message here...
Posts: 2,837
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Post by uuu on Feb 20, 2014 13:17:26 GMT
Talking of 3D printers, I'd like one to print...
...letters.
You see my current 2D printer only prints the ink bit. With a 3D printer it could produce the paper as well. Already folded in the envelope!
Wilf
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Post by Roger on Feb 20, 2014 13:24:32 GMT
He's a resourceful guy and manages to make this with no machining tools at all. Full credit for that, but what an awful lot of time and effort to make something that's trivial to make with a milling machine. I just don't understand the logic of doing all that when the time and money spent on raw materials and gas could have been put towards a cheap mill. He's rightly pleased with the result, but it really needs machining to make it accurate enough for the job. It's an interesting video though. |
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ennech
Active Member
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Post by ennech on Feb 20, 2014 14:34:42 GMT
I do agree with you Roger. I think the process is best suited to something that has more shape in it that would be difficult producing by machining'
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abby
Statesman
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Post by abby on Feb 20, 2014 20:29:34 GMT
Something like this perhaps.  for a 5" gauge engine or this gauge 1 Southern region tender axlebox  or these valve rod guides for Roedeer  All castings drawn in 3D Viacad , printed by Shapeways and cast by me in the shed using lost wax process. |
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