3D Printed USRA Heavy Mikado Tube Pilots

[lfisher]

After going through a few cast iron pilots, this solution came to mind. After installing the first one on Ron Wilkerson's Mike I was surprised by the enthusiastic reaction it received. As a result I've decided to add it to our offerings at Fisher Detail Foundry. More information is available here: https://fisherdetailfoundry.wordpress.c ... ube-pilot/

[Harold_V]

I've often wondered why ductile iron isn't used in such items, in lieu of gray iron, which has little tensile strength, thus is easily broken. Any reason why it couldn't be so cast?

Harold

[lfisher]

Great question. I suppose one could cast them using ductile iron if inclined. In our case the 3D printing approach resulted in a strong yet semi-flexible alternative that has the same appearance as iron. The previous four grey iron pilots didn't take much to shatter and upon examination you could see the crystalline structures at the break points which to me indicated some pouring or cooling issues in the original parts.

[SteveM]

Plastic live steam models! What's the world coming to?

He might be 3-d printing in metal.

Steve

[Fender]

Is this part polished after it is printed? The parts I have had made in "strong and flexible" material showed some lines/ridges on the surface. Polishing is supposed to smooth these out.

[lfisher]

While it is entirely possible to 3D print these using a sintered stainless steel process, the pilot would be prohibitively expensive. I do use direct to print sintered stainless steel for other parts however. In other cases we print to wax and then use traditional investment casting to produce parts in brass, bronze, etc.

On the question of polishing and print lines, the pilot was lightly media blasted which achieves a finish texture that is similar to cast iron. The piece which is made of Nylon is then stained black. There is some porosity so if painting the part one needs to prime and use multiple coats if you want a glossy finish.

My goal in starting Fisher Detail Foundry was to utilize 3D printing and traditional jewelry foundry techniques to produce detailed elements that are not usually found in our hobby. While the pilot isn't unique in its design, the use of the technology is worthy of note. Clearly there are some applications where this technology departs from traditional metal working. Take a look at Mike Massee's cover story in the current Live Steam magazine.

Best,

Larry Fisher

[lfisher]

Here's a photo of our 3D printed nylon pilot as installed on Ron Wilkerson's USRA Heavy Mikado. The results speak for themselves.

[optigman]

Very nice results. Also a nice alternative to pilots prone to breakage and high cost of replacement. Amazing what can be 3D printed with good results mimicking the original pilot.