pic: Bane Bots Gearbox CAD

[ducttapedude]

IMO Delrin a solid delrin plate ends up being about the same weight as a heavily machined plate of aluminum but not nearly as rigid. I've seen a few delrin gearboxes and you can seem them flex pretty easily, not anything horrible or dangerous, but noticeable. Also, the threading the in the delrin does not last as well, you can use a nut of course, but, just another con in my opinion.

Originally Posted by AdamHeard

I've found delrin to be uniformly less expensive than aluminum plate of equal thickness.

Delrin actually works out rather well, you can leave it nice and thick (1/4" for example), not pocket it out, and still be rather lightweight (equivalent to a about the weight of a 3/32" aluminum plate). If the gearbox is designed correctly for the material, it is plenty stiff. A nicely pocketed 1/4" Aluminum plate is usually in the ballpark of a solid delrin counterpart, and the delrin will take less time to produce (you can cut it faster, and by leaving it solid, have less to cut as well).