The (Unfinished) Arnold-Minitrix Shay

Part 1 of 3: Mechanism

Back in the mid-1970s, I desperately wanted a Shay for my little logging railroad. Such a thing did not exist, so I built my own. Not having a machine shop—let alone the skills to use one at that time—I had to make do with what I could assemble from the comparatively limited assortment of merchandise available in those days, using only simple hand tools. Given that, today, one can purchase an exquisite, accurate N scale Shay from Atlas for a very reasonable price, it probably isn't worth the effort to attempt what I had done thirty years ago. Yet my clunky old No. 6 still seems to generate interest, so here's what it took to make it.

Back in the day, Minitrix was the industry leader in N scale, with a line of exceptionally well-built locomotives. About the time I was pursuing the Shay project, there were enough raw materials at hand to fashion something vaguely resembling a Shay, which back then was sufficient for most modelers.

I started with the guts of a Minitrix Fairbanks-Morse H-10 switcher (above), the selling points being its compact length and versatile mechanism parts. Some other assorted parts are blended into the mix—details to come. The first stage of modification was to chop away nearly half of the frame. After firmly clamping the frame in a vice, I cut away the excess material with a hacksaw.

Cutting had to be done with the utmost care in order to avoid placing any strain on the remaining slender parts along the bottom of the frame, some of which had a profile measuring only fractions of an inch. All of the cuts were smoothed with a flat file; burrs and hard edges were removed with a steel wire brush; then the frame was thoroughly cleaned to remove all traces of metal residue.

Instead of the original FM trucks, I used a pair from a friend's derelict Minitrix U28C to take advantage of their slightly shorter wheebase. Granted, the minuscule difference between them (shown at right) almost wasn't worth the effort, but given that any typical diesel truck was enormous compared to that of a Shay, I was eager to save every possible scale inch.

After lopping off the dummy third axle sections of the truck frames, I had to modify the wheel wipers, insulators and side frames to work with two axles instead of three. The small hole conveniently located on the bottom center of the truck frame was tapped for a new 1-72 "junk box" assembly screw, since the portion that was removed also served as an attachment point for the side frames. Finally, the Rapido couplers were replaced with Micro-Trains. In the photo below, the truck parts on the left are the originals; on the right are the modified parts.

Since the center of the frame was narrowed, the fuel tank, which held the electrical pickup plate in place, had to be discarded, and so I needed to devise some new way to secure the pickup plate. Unable to come up with something clever, I resorted to permanently attaching it with an extraordinary new (at the time) product called "Krazy Glue" (a.k.a. CA). The insulator and pickup plate were modified as shown at right, with unmodified parts on their left. The wire, which originally powered the headlight, was instead connected to the motor.

With all of the major modifications done, the mechanism was ready for reassembly. One (literal) twist I did was flip the motor end for end and also rotate it on its side. My motive for doing this was to keep the boiler as low as possible; however, this meant having to make a large, unsightly rectangular enclosure behind the cylinders for the armature. In retrospect, I might have been better off leaving the motor oriented vertically and just raising a short section of the boiler under the steam dome—the cab would still have fit. But thirty years after the fact, hindsight can be mighty sharp, if useless.

Next up: the shell.

Continue to Part 2
Return to Chapter 3
Return to Clinic Index