[Matt Reiland]

I agree with Paul in every way (even though I don't have his mechanical background)

For our arm gearbox (with a 3.2 ft lever arm on it that was very abused last season) we used the standard little adapter gear that came with the (Edit) Chiaphua (Edit), to a brass gear that we had laying around at 32 pitch then we went to 20 pitch 20deg pressure angle for the 2 final stages and never had a problem, these gears are 'seriously strong' looks like something you would see on a small riding lawn mower. All were welded except the brass which was double dimple set-screwed and green loctited (it's never coming off)

For the drivetrain, same thing the output stages were 20 pitch 20 deg with no hint of problems on four different gearboxes.

From what I remember Dr. Joe posting straight spur gears offer about the highest efficiency of any of the different gearbox designs.

All gear gearboxes are more difficult to build than putting two sprockets on shafts and running chains between them but sized correctly they are incredibly strong.

For our metal gears, all were lightened to only 20-35% of their original weight mostly by removing most of the hub, and machining holes into the face, we didn't need a very thick hub since they were all welded