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Unread 16-01-2006, 02:44
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blowing things up, making things go
AKA: Megan
FRC #0888 (Robotiators (Glenelg Gladiators))
 
Join Date: Dec 2005
Rookie Year: 2004
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Re: how far have you gotten on your robot?

Quote:
Originally Posted by gondorf
actually our robot was upside down and we were staring at it dumbfounded.

the motor was plugged in but the gear that it was attached to was stuck

and during all this i thought: dont those look like the cookies i put in the oven before school...the oven is still on...oh no!!!
aha! OK here's what went wrong. If the gear that the motor's output shaft was attached to was stuck, the motor was doing only what it knows how to do; it wants to move. It will keep forcing its way, drawing more current, trying to get its output shaft to move. If it's locked up, eventually the motor burns itself on the inside.
This is why we gear motors down. If you attach the motor directly to the wheel's axle, it doesn't have enough initial acceleration to go from zero to its max rpm, which is what it's trying to do. You know we solve this problem by putting a gear with fewer teeth on the motor, then a bigger gear on the wheel, and you get a ratio. The motor has to rotate several times before the one on the wheel makes it all the way around, but it's actually a good thing because it prevents it from locking up. The motor gets to move right away, so it's happy.
The worst thing that can happen is the motor is trying to move but can't, and then it keeps trying until it burns out. In the future, make sure the motor is free to move before you turn it on, and be ready to turn it off right away if something doesn't seem right.
A lot of other things could go wrong. You said you were using the kit, so I hope you were using the correct motor. It's the regular CIM motor, not the larger ones; part numbers FP801-005 vs FP801-001.
When motors are gone, they're gone. Spare parts are in 5.4.5 of the manual (you feel kind of crazy when you have a copy of the manual on your bed) the URL for the IFI store is http://www.ifirobotics.com/0-index.htm and I don't know how long it'll take for them to get there, so hurry.
I hope some of the things covered in this post were already familiar to you.
If you need more help, CD is the right place! Good luck!

Last edited by atomikitten : 16-01-2006 at 02:47. Reason: it's IFI; I must have Freudian-slip-typed IRI because I love IRI