501 needs your help – P60k 256:1 Banebots Transmission

[fox46]

How much inertia does the arm have? how much load is on the transmission when you change arm travel direction?

This is exactly why we are having issues but that comes back to the marketing of a gearbox for a motor which it can't handle. The load on the motor is almost nothing but the speed at which they start and stop is what is wearing them out. We have the programmers working on a ramp function / soft start function for them which should help.

This is still a highschool competition and these machines are being built by highschool students, not engineers.... or at least thats how it should be. When we got our gearboxes, they were given to a couple of students who were told to disassemble these, figure out how they work, then reassemble them with grease. Of course they aren't going to be able to identifty the weaknesses in a design- they are just beginning to learn this stuff. I just would have preferred they learn about it in a different way in this case.

[AdamHeard]

Originally Posted by fox46

This is exactly why we are having issues but that comes back to the marketing of a gearbox for a motor which it can't handle. The load on the motor is almost nothing but the speed at which they start and stop is what is wearing them out. We have the programmers working on a ramp function / soft start function for them which should help.

This is still a highschool competition and these machines are being built by highschool students, not engineers.... or at least thats how it should be. When we got our gearboxes, they were given to a couple of students who were told to disassemble these, figure out how they work, then reassemble them with grease. Of course they aren't going to be able to identifty the weaknesses in a design- they are just beginning to learn this stuff. I just would have preferred they learn about it in a different way in this case.

Banebots posts maximum torque ratings for the gearbox on the page they sell them on, and based on those ratings the 256:1 is a poor choice for anything that will see stall loads.

I would stick to the 64:1 or less (4:1 for us), and make/get a different style gearbox for the comp bot, even if you take measures to alleviate the load, the potential for failure with the 256:1 at full motor stall is always there, and could totally wreck your season.

[MrForbes]

Originally Posted by fox46

This is still a highschool competition and these machines are being built by highschool students, not engineers.... or at least thats how it should be.

That's debatable. If you have an engineering mentor who understands how to design this stuff, that mentor should be helping the students figure out how to make a workable design--that includes making sure the parts are strong enough for the application.

I realize that many (most?) teams don't have a mechanical engineer helping them, the result is that we kind of need to have indestructible parts available. That's a tall order.

[sanddrag]

For those of you with failing BaneBots planetaries, you may want to look into Dewalt Drill gearboxes, and/or a hypocycloidal lug nut torque multiplier. Ours has been holding out so far, but it hasn't seen a lot of heavy use. We have the 256:1 with a steel ring gear. In our design, it should see no more than about 15 lb-ft, and it is well supported on the end. I hope it lives, but I'm prepared to deal with it if it doesn't.