21-03-2011 14:55

Alex Cormier

Re: pic: FRC 51 - Wings of Fire Preship

Another great looking robot from this team. I have a few questions, why did you have the cord coming from the window motors so long? Also, I see that you didn't gear the speed up, rather you geared it down. Is there a reason for that as well?

Thanks!

Hopefully I'll have some time to check this bot out in STL.

21-03-2011 15:15

Chris Hibner

Re: pic: FRC 51 - Wings of Fire Preship

The cord from the window motors are belt-drives for the gripper. It's so long because we wanted the motors back at the pivot point of the arm so the torque required to move the arm is as small as possible.

For the gearing, it's actually direct drive off of the window motors. We have bigger pulleys driving the gripper now, which makes it a little faster.

21-03-2011 15:38

Alex Cormier

Re: pic: FRC 51 - Wings of Fire Preship

Did you have any trouble of the cord slipping? We had a gripper setup with the window motors and cord as well. We had some slippage in a few different variations.

21-03-2011 16:03

Chris Hibner

Re: pic: FRC 51 - Wings of Fire Preship

The cords slip a little, but not too often. We don't consider that a problem - we consider it a clutch that keeps things from breaking.

22-03-2011 18:16

Rob

Re: pic: FRC 51 - Wings of Fire Preship

Beautiful machine again this year Chris!

If slipage is an issue try routing your drive cords in an "X" shaped loop rather than an "O". This will get you a bit more wrap over the drive pulleys.

~Rob

22-03-2011 21:10

Alex Cormier

Re: pic: FRC 51 - Wings of Fire Preship

What I also did was use a "floating tensioner". (a zip tie)