G scale / 1/32 scale wheels and tool

thingiverse

This is a wheel design and alignment tool for wheels used in G scale garden railways. I set this up to help design the 20mm wheels for my tram http://www.thingiverse.com/thing:1379253, and for the 30mm wheels for the 12 ton coal wagon http://www.thingiverse.com/thing:1572391. There are some instructions in text form in sketches in the 23D file, but essentially this is a G1MRA standard wheel profile with an axle centreline clearly defined. You then select and "revolve" the profile around the axle centreline line to produce a basic solid wheel. There are some other parts in the 123D design file that help "drill" a rectangular tab into the wheel so it can be motor driven, and a stub axle that fits this hole and fits the wheel to a "TT motor" as used in my tram design. These were dimensionally tweaked so that they produced a nice fit with my printer in ABS. The tram wheels were solid and 20mm dia, but I have also included the 30mm spoked version that I used on the 12 ton wagon. Other diameters can be easily produced by drawing a new centreline and making sure that you include the 1.5mm block that produces the 3mm hole in the middle of the wheel. Spokes can be easily introduced by producing a linear extrusion for the spoke and then using the "circular pattern repeat" function in 123D, and then add a rim produced by the revolve function as in the solid wheel, but only selecting the outer part of the profile. The wheel profiles include a "cut out" that can be used if you want to experiment with "tyred" wheels to try and get better traction. I fitted some with square section rubber bands, and they gave better traction, but I think they are less reliable on the actual track. There is also a 20mm stub axle that can be used, but I found these unnecessary when I was making the wagon, which just used the wheel as "revolved", without the rectangular tab being added or more correctly subtracted. A fitting tool is also included that is very useful when pressing the axle shaft into the wheels, as it keeps the 40mm back to back distance setup nicely when pressing the axle in. Post-Printing Always drill out the centre hole carefully to keep the wheel properly aligned. I use a 2.9mm drill to keep a nice tight fit on a 3mm stainless steel shaft. Press the axle in using a drill press to keep the axle properly aligned, and use the tool to keep the 40mm back to back spacing.