Lego Steam train connecting rods

When I first got into this hobby of Lego trains and 3D printing I found a lack of custom parts available for download. All the builders seem to use 3D printed drive train parts and they are available for purchase from various websites but these things aren't hard to create.

These connecting rods are just ones I have created for my models and it took a little time and effort to get them to function properly without undue friction. I tried to keep it simple so as to not draw away from it being a Lego train. These are half pin width (4mm) so two can fit on one pin, or use ½ pin for single.

I print them with supports from base plate only and a 1 layer raft optional. Only the pin sockets sit on the build plate and require support for the joining beams. This raised feature stops the rods binding, scrapping wheel faces and reduces friction (improves battery life). I also change my bridge infill direction to 45 degrees for better results.

Post printing I use a 3/16" (4.8mm) drill to clear out the holes and the pins should lock in nicely.

Format of my file names is number of connecting holes x length beam (in lego hole increments) and I can produce custom sizes by request as I draw all my things modular instead of starting from scratch. I will keep adding more so look for updates.

Update 9/11/24 - Added 2 x 5 and 2 x 6 hole rods

Update 11/8/25 - Added 5 x 5 hole rod