3D printing
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IIRC (and I should know, so it annoys me that I haven't looked into it recently) Porsche prints engine pistons using a metal powder and sintering process. Even super high-temp metals can be printed this way.
For low melting point metals--bismuth types--you can print concave molds straight away, or convex mold masters which you use to make silicone molds (which you then pour). There will be shrinkage issues, so experimentation will be needed.
Bismuth metals are the sort that have ultra-low melting points, depending on formulation. They have densities close to lead, but are (I think) non-toxic, and can be used to build things like special car weights or locomotive frames. Some of these will melt at temperatures so low that you wouldn't want to leave them in closed car on a hot day in the sun, lest you come out to find all your hard work has puddled on the carpet.
Those types are, necessarily, quite soft, so unsuitable for wheelsets, however. Not sure about frogs or guardrails, etc, but I have the idea that the higher the melting points, the more durable the parts, so I would imagine there would be some formulation of a bismuth type metal that might work. There would probably be long-term wear issues too.
The channel has a number of others too, and I'd look them over to make sure all the parts of the process are understood. This looks quite promising, and is certainly DIY.
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You're looking at SUPER high end printers (aluminum powder bed fusion is one of the technologies I've read about) to do something like this today - probably in the six figure range. Consumer-grade printers typically use either filament or resin, both non-conductive. It might be possible to design something like this and outsource printing to a specialty outfit, though.
Actually there are conductive FDM filaments. Not sure about the durability. So like Troy said still might be cheaper in the long run to purchase a new turnout.
Very cool! TIL.
Snowman
Well-Known Member
Yes, but perhaps at a highish cost. If you are looking for conductivity for something like car wheels (for connecting with resistors, etc.) you might also look into metal powder and/or conductive graphite additives for SLA resin printing.
IIRC (and I should know, so it annoys me that I haven't looked into it recently) Porsche prints engine pistons using a metal powder and sintering process. Even super high-temp metals can be printed this way.
For low melting point metals--bismuth types--you can print concave molds straight away, or convex mold masters which you use to make silicone molds (which you then pour). There will be shrinkage issues, so experimentation will be needed.
Bismuth metals are the sort that have ultra-low melting points, depending on formulation. They have densities close to lead, but are (I think) non-toxic, and can be used to build things like special car weights or locomotive frames. Some of these will melt at temperatures so low that you wouldn't want to leave them in closed car on a hot day in the sun, lest you come out to find all your hard work has puddled on the carpet.
Those types are, necessarily, quite soft, so unsuitable for wheelsets, however. Not sure about frogs or guardrails, etc, but I have the idea that the higher the melting points, the more durable the parts, so I would imagine there would be some formulation of a bismuth type metal that might work. There would probably be long-term wear issues too.
Added some more details to the tank car model. The ring around the dome that lays on the body was tough to construct, but ultimately got it done with a combination of intersections and differences - it's a very different way of thinking of things for sure. Next step, getting rivets on the ring - I think I'm going to have to bust out some trigonometry to get that part done 
Looking ahead to printing - I'm guessing I could print this as a solid potentially. But probably better to make it hollow in order to add weights, which probably means printing the end caps at least, and probably the dome as well, in separate pieces. Any general advice for how to break up models for the best printing? Most of what I've read seems specific to FDM, trying to minimize or at least control banding etc.
Looking ahead to printing - I'm guessing I could print this as a solid potentially. But probably better to make it hollow in order to add weights, which probably means printing the end caps at least, and probably the dome as well, in separate pieces. Any general advice for how to break up models for the best printing? Most of what I've read seems specific to FDM, trying to minimize or at least control banding etc.
Looking good @Vince-RA. Remember, modules are your friends. They speed up rendering and allow you to repeat things. Here is a logging car I made with OpenSCAD. https://www.thingiverse.com/thing:4307905
Ve
Very cool, looks great! Most of the tank car is modularized where I thought it made sense. Still getting the hang of when to modularize, proper scope of modules, how to create them for the best flexibility in use, etc.
I have printed a small group of Narrow Gauge tank cars, hollow. I don't think a solid one would work very well besides using a lot of resin. I suspect warping would be a consideration as well as interior curing. I weighted my cars in two manners, one left a hole in the bottom to pour in small lead shot and the other printed the dome as a separate part. The advantage of pouring in from the top was a a glue could be poured in after the shot to stabilize it. The ones with the bottom pour (then patched) was a shake was necessary to distribute the lead before placing it on the track. Ah rivets! They really increase the file size and with enough want to bring your computer to a grinding halt. The only worse item to compute is spirals of coil springs such as on trucks etc.
Keep plugging away, it's how you learn! Tom
Keep plugging away, it's how you learn! Tom
Always exceptions! This C&S Gondola taken from Narrow Gauge Gazette in Feb, was printed in five basic pieces, sides and bottom Details such as un coupler bars, turnbuckles, brake hand wheel etc added later, turnbuckles and such printed, steel piano wire used as appropriate. This one is on Kadee HON3 trucks though now I am printing my own using the Kadee wheel sets.
Snowman
Well-Known Member
Just stumbled across this YouTube video about electroplating 3D resin prints (conductive).
The channel has a number of others too, and I'd look them over to make sure all the parts of the process are understood. This looks quite promising, and is certainly DIY.
Certainly evolving technology, quickly! For SLA (Resin vat) printing, orientation and support arrangement is quite critical to the outcome. My latest prints are of flatcars, designed so as to include a steel flat bar stock for weight. Printed flat these wouldn't take long to print but this introduces a tendency to warp and poor details and geometry on the bottom. So far I have had best results printing at 35-45 degrees inclination, which takes about 16 hours to run. The first cars I printed as a frame and added an individual planked wooden deck, the current one has a printed deck which seems OK.
I assume the extra time is in large part due to adding a bunch of printing of supports?
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