Weaver RS3 work in progress

[Bob]

I have an old Weaver RS3 "kit" that needs a Portescap coreless motor so that I can install an HO DCC decoder. There is not room for an ESU 5L decoder, but one of their HO decoders can fit. However, the OEM Pittman motor draws too much current for an HO decoder. What to do? Replace the motor.

This turned into a major 3D printing project. What we see here is a work in progress. A lot more features need to be added to the Fusion 3D model.

The red "bathtub" printed parts are actually molds for Cerrobend weights that replace the OEM weights and increase the weight of the model by about 1/2 pound. No doubt the details will change as I work on the models in Fusion 360.



I also ordered some steel Woodruff key stock from McMaster and that will provide about 2.5 ounces of frame stiffeners to prevent the weak Weaver frame from bowing and cracking.

What prompted this project is a request from the Poobah David to put better sound in his RS3 and also in an unbuilt RS3 kit. This proved a great opportunity for me to re-learn what I forgot in using Fusion 360.

[Craig]

Looks great Bob!!!  Any ideas when the Cerrobend will get poured?

[Bob]

Hopefully pretty soon. I originally wanted to print the final molds in ABS, but even with supports some of the overhangs are coming out too gnarly to use. Now I'm starting to print what I hope to be final parts in black PLA. Jeff Kraker successfully pours his using thin PLA molds. However, he does the pour with the mold sitting in a bowl of ice water. I do expect the Wood's metal to expand about 1% as it cools, caused by the high bismuth content.

Over the last few days I have found numerous tweaks and improvements to simplify things such as wire management. That seems never ending.

I did print the motor mount in ABS so that it would be more resistant to heat from the motor. Weaver's OEM body mounts are horribly undersized and weak. They crack as soon as the provided self-tapping screws are inserted. I made ABS covers that slip over the OEM features with brass threaded M2 heat stake inserts. These are in ABS so that they can be solvent welded to the styrene locomotive shell.

I'm wondering what to use to remove Weaver's pad printed lettering without destroying the paint below. Any thoughts?

[Craig]

What printed pads are those Bob?  Can you post a picture?

[Bob]

That's pad printing. This was used by Weaver, Red Caboose, Intermountain and others back in the day as a way to decorate models with lettering, logos, etc. I watched the process many years ago during a tour of the Intermountain factory in Longmont, CO.

A flat metal printing plate was exposed and etched so that the artwork pattern for a single color was left proud of the field. A machine inked the tops of the letters, then moved a very soft silicone pad over the plate to pick up the ink pattern. The pad then moved over and pressed the ink pattern onto the side of a locomotive shell or car body. The soft pad was able to conform to irregularities in the model surface such as rivets and some ribs.

I want to remove the ink without damaging the underlying paint. So far I've received recommendations for Microsol and Testor's ELO, locally applied.

[Bob]

I just glued the ABS repair body mounts to the inside of my RS3 shell. Sliding them over the weak Weaver mounts accurately locates them. These must be installed at least 0.1" away from the bottom lip of the shell because the shell slips into a groove in the plastic frame. In the photo below notice that the Weaver mount on the top has already cracked.



New mounting holes need to be drilled into the frame. I haven't used these yet, but I made two different types of marking screws. The idea is to put paint on the head of the screw then slip the shell over the frame far enough for the screw head to make contact. Both of these started out as steel M2 x 6 cap screws.



An initial test fitting of the shell on the frame was successful. The new mounts slipped snugly into cutouts in the weight molds.