This is a replacement frame for the HO scale MDC/Roundhouse Old Time 2-8-0. It is designed to be a direct replacement for the original frame, with the following improvements:
Note: This is a test version, and not all of the dimensions have been checked against various versions of the MDC model.
- Since it is plastic, the motor is automatically isolated from the frame, making it easier to install DCC without replacing the motor or finding a plastic metric motor mount screw. For the same reason, metal couplers can be used without any chance of causing a short circuit.
- All axles except #2 are on springs, allowing them to adjust to uneven track. The partial equalization is as described here: http://www.2mm.org.uk/articles/new_comp_article/index.htm
Note: For models with single piece side rods, this will require new rods to allow the axles to move relative to each other.
- Holes are provided to accommodate all of the gear arrangements used by MDC, as well as both versions of the Northwest Short Line regear kits.
Install your coupler of choice at the front, and reassemble the model. Additional weight might be needed to make up for the lost weight of the metal frame, though the MDc boiler is fairly heavy on its own.
- Remove the four axle retainer plates from the top of the frame and trim off the sprues.
- Tap the holes fore and aft of the axle bearings for 00-90 screws. Take care not to twist the springs which hold the bearings for axles 1,3, and 4
- Remove all of the parts from the original frame, and mount them on the new frame.
- Make new electrical contacts as follows, using metal sewing pins and Kadee coupler springs:
- Cut eight pins slightly shorter than 1/4". The goal is to ensure that when the heads are pressed against the backs of the wheels, the ends will not touch each other.
- Thread a coupler spring onto each pin, and insert them into the holes in the axle retainer plates.
- Using 00-90 round headed screws, attach the axle retainers to the bearings.
- Solder fine stranded wire to each pin, taking care to route the wire around the drive gear. Connect those wires to the motor, or to a DCC decoder.
- It may be necessary to trim the back of the wheels slightly, if the plastic center protrudes and prevents the pin head from making contact with the metal rim.