Building an N-Scale DM&IR 0-10-0 Switcher

A Minitrix 2-10-0 Provides the starting point

The Minitrix 2-10-0 has been around for some time and if you are like me, you have a couple in your collection. The 2-10-0 mechanism makes a good starting point for this project. I used the Missabe 0-10-0 switcher as the Prototype. The finished product doesn’t match the prototype exactly. In fact if you compare the model with the prototype there are quit a few discrepancies, but the results give a good effect.

The parts needed for this project is a Sagami 142039 Can motor, a Timewell Flywheel # 115, a Bachmann 2-8-0 or 0-8-0 boiler shell, 1/2 inch Plastruct Tube and some very small stranded wire. These parts can be obtained at most good hobby shops or direct from Walthers. The Bachmann boiler can be ordered from Bachmann directly or you may have one from an existing locomotive.

Disassemble the entire Minitrix mechanism down to the bare frame. On past projects when I didn’t completely disassemble the mechanism, I spent more time cleaning the small filings out of the locomotive and never was satisfied with getting it fully clean.

Fig 1.  Completely disassembled frame before modifications.


The first modification is to cut the front of the frame off just forward of the valve assembly channel. The second is to trim the side reinforcement in the motor mount area to allow clearance for the new can motor.

Fig 2.  Frame after modifications.


Carefully remove the worm gear from the existing Minitrix motor. Use a small piece of an Allen-Wrench as a hardened punch (smaller than the shaft diameter).  Cut a slot in a metal shelf bracket as a holding fixture under the worm gear while driving the shaft from the gear. A #53 drill bit works as a good ream to enlarge the hole in the worm gear so it will fit the Sagami motor shaft. Bolt the Sagami motor in place on the frame, align the worm gear over the drive gear and secure it to the shaft with a drop of CA glue (Cyanoacrylate). Glue the flywheel to the shaft on the opposite end from the worm gear. Care must be taken when using CA types of glue. CA glue will ruin the motor and gear assemblies if any of it gets in where it is not supposed to go. The motor must be installed on the frame first before installation of flywheel. Use a Dremel and cutoff disc to trim the excess motor shaft length at the flywheel. Painting the flywheel black helps conceal it underneath the cab. Then reinstall the driver wheels, valve gear assembly and electrical pickups. At this point hook up power to the frame assembly and see if there is anything binding. It is very important to keep the moving parts free of dirt.

Fig 3.  Assembled Frame


The starting point for the boiler is Bachmann 0-8-0 (2-8-0) shell, The first modification is to remove the cabs from both the Bachmann and Minitrix boilers. Fit the Minitrix boiler cab to the Bachmann boiler shell and glue using MEK (Methyl Ethyl Ketone) or liquid plastic model cement. Next, lengthen the Bachmann boiler 1.1 cm behind the smokestack. The boiler extension is a piece of 1/2" Plastruct tube double wall thick. Cut two pieces of tube about 1" long. Cut one of the pieces lengthwise down its side so it can slip over the top of the other piece. Secure the two pieces with MEK. When dry cut to length and fit to the boiler, Use sheet styrene to extend the walkways on each side of the boiler. An electrical resistor with thin paper bands works well as an extra tank below the walkway on the left side of the boiler. The front ladders are moved back so they don’t protrude past the front plow. When making the modifications to the boiler pay attention to keeping your cuts straight and square.  Work slowly and be very patient.


Fig 4. Finished model.  Notice the boiler extension and "resister" tank under the walkway.


After boiler modifications are done a small amount of internal boiler grinding will be required to fit it to the new frame mechanism (mainly around the cab). Add as much lead weight as possible to the front of the boiler and use the same bolt that fastened the original boiler to the frame for the new boiler.

The prototype has an unusual tender. The tender is built up of sheet styrene on the original Minitrix tender frame. The water port hole, on top of the tender, is from an old tank car. Although, you can continue to use the existing tender from the Minitrix Locomotive for your model if you wish.

Electrical pickup, from the tender, is important for smooth operation. Reuse existing tender pickup from the Minitrix tender, except solder fine stranded wire from the pickup wipers on the tender to the new Sagami motor. Each truck on the tender provides power from one of the track rails. Make sure the wire doesn’t touch the flywheel when entering the cab. A new draw bar will allow close coupling of the tender to the boiler.

I did this project not only to have a 10 wheel switcher in the fleet, but I did it for the effect that is model has.  Creating something very close to the prototype is difficult (remember - this is N scale).  My locomotive was well received by my fellow GRVS club members.  It runs smooth and slow over all kinds of track without derailing or picking switch points (The lack of leading pilot wheels may have something to do with this).  This project is a little involved, but the results are well worth the effort.