Non-FIRST Motor Suggestions?

[pilleya]

Originally Posted by ctt956

I have decided to go with two CIM motors, as I'm familiar with them and they have gearboxes, controllers, etc. easily available. The duty cycle isn't much of an issue, as they won't be running long or working as hard as they do sometimes in FRC. I think I'm going to go with BaneBots 220 gearboxes, or maybe Toughbox Micros. The BaneBots seem more durable, but the Toughbox has higher torque(I think? 12.75:1 vs. 4:1).

In regards to the gearboxes, you need to carefully consider your gearing. A Toughbox Micro( geared for 12.75:1) is going to mean that your robot is geared for about 14.6fps with 8inch wheels(without losses), that is double the speed that you said you required, with only one CIM on each side and 240lb’s of robot weight, that seems like it is going to be difficult for your motors and you will have very little capacity to go uphills without huge current draws. You definitely cannot use a 4:1 BB gearbox , that is simply not enough gear reduction( you would need to use a massive sprocket in order to get your 2rd stage reduction which probably wouldn’t be practical) you would need to use the 16:1 at a minimum.

In regards to durability of the gearboxes it pretty much depends on how you are going to be mounting your gearboxes. If you are planning to have two axles with 120lb load on each, you certainly need to support your gearbox shaft well. You will need to make sure that you have a support on both sides of the gearbox shafts. With the micro, you should be able to use the gearbox shaft( made from 4140 steel) as your drive axle, but you will need to support each side with bearings. I would recommend that because of the 12.75:1 reduction of the Micro, that you should have a separate axle for your wheel and have a 2:1 or 1.5:1 belt (15mm as a minimum or use #35 if you don't want to risk any failures) or chain (#35 as #25 won't be strong enough). If you opt to use a Banebots planetary gearbox, you will definitely need to have a separate axle as the output shaft is only 1.5 inches long, and will not be long enough for having a wheel( 2 inch wide hub) and supporting both sides, which will take up approximately 16mm( including bearing flanges). The axle is far too short for this purpose.

Originally Posted by ctt956

I know I would probably need bearings and mounting brackets, but would I need any additional hardware to mount the AndyMark 8" Pneumatic Wheels to either of those gearboxes? The link for the hubs doesn't work. The wheels' load capacity is listed at 120 lbs., but that's for one, I'm assuming. So two would have a capacity of 240 lbs. I know robots weigh more than that with a battery and bumpers...

In regards to the wheels, while the load capacity maybe 120lbs you will experience a significant “ballooning” of the tyres, due to the high load that they will be under.

I would suggest contacting AndyMark to ask about the load-rating of the wheels, VEXpro rate their wheels as “Conservatively rated for use on 200 lb robots” and I’m not sure if AndyMark do something similar. There is a big difference between a FIRST robot which might have 6 of the wheels and weigh 120lbs and a robot that weighs 240lbs and has 2 wheels.

In regards to the hubs it will depend on what output shaft you order the Toughbox Micro with:

If you get the ½ hex output shaft you will need these hubs:

http://www.andymark.com/Hub-p/am-0096a.htm

If you use the BB gearbox( which shouldn't matter because you won't be able to mount the wheel directly to the shaft ) or the ½ round keyed output shaft you will need these:

http://www.andymark.com/Hub-p/am-0077a.htm