This is a very cheap and simple test stand for locomotives with rollers.

Does not use bearings, rollers are made of washers. This gives slightly more friction but still works good if assembled correctly.

Rollers are put on a code 100 track. Other types of track will probably work too.

For a 4-axis locomotive you'll need 4 pieces of this.

UPDATE This is not a very good design. Too frequently the washers do not spin freely, that causes the locomotive to move from the stand

To support one wheelset you'll need:

• printed case
• 4 M3 conutersunk screws (I used M3x14 and M3x10)
• 8 M3 washers
• 4 M3 nuts
• 10-15cm of single-core wire (I used wires from ethernet cat5 cable)

• Print plastic case.

Print in normal orientation, configure supports to support horizontal overhangs but not sloped surfaces. I used ordinary PLA.

• Screw in the screws with washers from inside of the case.

Make sure that washers are freely spinning but don't skew too much. You'll need either a very small screwdriver or use pliers or tweezers.

See picture for details.

• Bend wire and insert it into case to according to picture.

If your printer produced small holes for wires at the bottom of case correctly, stick wire into that holes. If there are no usable holes, heat the wire with soldering iron or lighter/candle and melt it into the case. The wire must touch the rails when put on top of them and touch the screws.

• Lock the wire with nuts. Again make sure washers are freely spinning.