Rick -
I procured the FDM printer to make structural parts, primarily inside models, but also for custom fixturing for my Sherline mill and lathe. Most of my prints are extruded in ABS.

The GP9 under-frame detail rails are hard to see, so I won't try to hide layer lines and printing artifacts. For the most part they just fill a visible gap between the trucks and the frame that may be observed as the locomotives cross over the Ohio River bridge.

As I grow in my Fusion CAD skills, I wonder if a resin printer might be in my future...

Hey Bob!
I'm pretty excited about Craig's success with the smaller motor.  Do we have a full part number for the motor.  I've been digging through Portescap's website and catalogue but haven't found the exact motor.  It seems the 216E number is a suffix to the part number, but I haven't figured out what it indicates.  By matching the specifications you tabled, I might be able to figure it out, but I still have several hundred more individual spec sheets to compare!  Is Craig's example a single ended shaft, or double?

3D printing is definitely changing the landscape of model building! 
   

Craig -
When you are not dispatching on Saturday and your brother Mark sits on the "throne" you deserve a chance to run your GP35 on the head of a manifest train.

Here's a comparison between the Pittman 8x14 (Weaver, P&D), 8x13 (Overland) and Portescap. If you click on the chart and it looks funny, click again. PostImage is throwing a hissy fit when initially enlarging the JPG image.



Back to 3D CAD, Big Train James suggested trimming the inside of the Red Caboose walkways so that the speaker can be inserted from the bottom. That would permit the dynamic brake blister to be glued in place. So here's a fixture to hold the walkway assembly in the mill for trimming.



The 3D print came out great and fits like a glove. Overhangs on the bottoms of the two channels are not beautiful (it was printed upside-down) but that doesn't matter. The two holes are for bolting down flat aluminum strap clamps to hold the walkway firmly against the top of the fixture.

The white hazy deposit on the center of the fixture is stick glue that was applied to the QIDI textured build plate. It can be washed off with soapy water if desired.



Next I need to design the 2-piece speaker mounting clips. Why all this effort? With a bunch of models to build, time spent now should make the assembly line run a lot faster. That's my story and I'm sticking to it.

Getting back to motors, we just saw proof of the quality of a Portescap coreless motor on the A&O. Craig's Overland GP35 died with a shorted Pittman 8313 motor, which also destroyed the V4L decoder. Over the past few weeks Craig installed an eBay Portescap in his unit using 3D printed parts he designed and shaft couplers I turned on the lathe. He also plugged a new 5L DCC decoder into the carrier board.

Yesterday Craig ran it on the A&O, both light and with a 14 car train upgrade and downgrade. With default ESU 5L motor parameters it ran perfectly smoothly, better than any other locomotive on the A&O. The minimum speed was so slow it was almost impossible to tell it was moving. We opted to program an increase in the minimum speed because it was impractically slow.

Operation was nearly silent, with only a faint hum from back-EMF sampling. Curiously all this was with the default BEMF motor parameters that came in the sound file. We only changed CVs 2, 5 and 6.

The engine should run a lot cooler. The new motor produces 1.8 times more torque per Ampere than the Pittman 8x13. The stall current is only 1.2 A, so it can be used with an ESU HO decoder.

Everybody agreed that this was a roaringly successful transplant.

Sometimes when you have a hammer, every problem looks like a nail.

The alternative of milling the inside of the dynamic brake blister seems the most attractive. This morning I designed and printed a fixture to firmly hold the blister upside-down in the Sherline mill. Work holding is accomplished by a pair of 4-40 screws that pass through the oval cutouts for the exhaust stacks.