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Unread 18-01-2009, 15:14
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VEX Robotics Engineer
AKA: Arthur Dutra IV; NERD #18
FRC #0148 (Robowranglers)
Team Role: Engineer
 
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Re: Round Belting - Solid vs. Hollow, Polycord vs. McMaster

Quote:
Originally Posted by iCurtis View Post
In short, we found cutting the cord at 10% shorter to be pretty aggressive. At 3% shorter (instead of 10%) the balls moved just as well, and the whole assembly ran much smoother.

Art, is there any reason for the half hour cure time? After five minutes or so ours were cool to the touch, and we haven't had any fail that were joined using your welding method.
The 10% value comes from the manufacturer spec sheets. Normally, these belts are designed for conveyor-type installations, so having increased tension allows them to transfer more force through it. In our robots, we may not need the same level of tension depending on the application and polycord thickness. If you use something like 1/8" polycord, sticking to 8-10% reduction is a good idea.

As for the half hour cure time, again that's from the manufacturer recommendations. According to them, you can use the polycord after five minutes, but full strength in the joint isn't achieved until thirty minutes later.
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Art Dutra IV
Robotics Engineer, VEX Robotics, Inc., a subsidiary of Innovation First International (IFI)
Robowranglers Team 148 | GUS Robotics Team 228 (Alumni) | Rho Beta Epsilon (Alumni) | @arthurdutra

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