Has Anyone Considered or Actually Done 3D Printed N Brass Loco Frames?

[tehachapifan]

Seems like this would open up a lot of possibilities, where the lack of suitable N scale frame halves has hampered some custom loco builds. A correct-length frame along with perhaps a custom-length 3D printed universal joint or two and bam! Am I correct that at least one 3D printing service offers a brass option now?

[reinhardtjh]

@bbussey had Shapeways print the chassis for his New Haven EP3

I've wondered about printing a frame for a x-10-x steam locomotive but am no where near ready to get serious about it.

[peteski]

@bbussey had Shapeways print the chassis for his New Haven EP3

I've wondered about printing a frame for a x-10-x steam locomotive but am no where near ready to get serious about it.

I believe that @Lemosteam has also printed some tender chassis in brass or stainless steel.

[tehachapifan]

OK, good to know this has merit! Now if I could just learn how to design stuff.

[reinhardtjh]

I believe that @Lemosteam has also printed some tender chassis in brass or stainless steel.

Yes, for his streamlined K4 kit, I believe.

[bbussey]

The EP-3 has a stainless steel frame. SS provides heft and conductivity and rigidity.

There are a number of 3D printing companies in the States (and elsewhere) that render in various metals to proper specs at reasonable expense. Shapeways isn’t the only option, nor the least expensive.

[Lemosteam]

While this can be done, it will be a very expensive trial and error process due to material shrinkage rates that must be accounted for in the CAD model.  Yiou cannot design to nominal and expect the part to be printed as such.

In the end I had to proportionally enlarge my CAD model IN ALL THREE DIRECTIONS to get the tender shell to fit properly on the chassis.  This means that holes become out of round, etc. and curvatures and shapes become elongated.

There are also minimum wall thicknesses and pin/feature diameters that will not print if too small.

[keeper]

This was printed in brass by shapeways.



It fits very nicely.

Thomas

[3rdboxcar]

While this can be done, it will be a very expensive trial and error process due to material shrinkage rates that must be accounted for in the CAD model.  Yiou cannot design to nominal and expect the part to be printed as such.

In the end I had to proportionally enlarge my CAD model IN ALL THREE DIRECTIONS to get the tender shell to fit properly on the chassis.  This means that holes become out of round, etc. and curvatures and shapes become elongated.

There are also minimum wall thicknesses and pin/feature diameters that will not print if too small.

Agreed, if you wanted something accurately printed in Brass takes a lot of trial and effort, I gave up due to cost, if it was shaped for a weight or something not that critical then ok.

[Chris333]

How are the dimensions when printed in resin then cast in brass?

[Lemosteam]

All materials shrink when cooling/curing.

The print and casting would have to be trial and error again.

This is why injection die casting works for the manufacturers. The molten material enters the mold cavity and cools on the die surface immediately, while the rest of the interior of the casting fills and cools slower and the part is ejected based on a time factor.  Still this process is fast enough to be used in high volume production and results in very accurate castings, essentially equal to the machined and polished tool with much less shrinkage than say a sand casting.