Banebots 42mm gearbox: Recommendations for use

[ZZII 527]

Originally Posted by gburlison

We are using the 42mm, 256:1 setup with a F-P motor. We have destroyed one carrier plate, but that was from a stupid mistake. We replaced that carrier, but would be very interested if you have a CAD model that we could use to have new carrier plates made. Thanks for all the research that you have done.

Here are the dimensions I worked from:

Thickness: 4mm (5/32" stock works perfectly)
Outside Diameter: 25mm
Double-D Diameter: 10mm
Double-D Flats: 8mm
Pin Pattern Radius: 9mm
Pin Hole Diameter: press fit for 3mm (#32 drill, 0.116" works well)

Material: According to Dr. Brooks, 4130, 4140, 4340 seem to be the best choices, as they are easily hardened to something like HRC40. I used A2 tool steel (mostly because it was the first thing I could get my hands on in 5/32" ground stock) and I have both annealed (~HRC20) and tempered (~HRC40) carriers. So far, the softer annealed carrier has been holding up fine, but I suspect that to ensure longevity of the plate, hardness nearer HRC40 would be better.

I cut them on a waterjet, so I went way undersized on the pin holes and reamed them out later to avoid issues with taper. (My CAD files are dimensionally quirky for that reason, so I don't want to post them as they might be misleading.) I also had to file out the double-D a bit to get it to slip over the shaft. (I wouldn't suggest pressing it on. I tried this and the alignment issues are not worth the hassle.)