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Unread 11-03-2014, 02:14
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JohnSchneider JohnSchneider is offline
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FRC #3310 (Black Hawk Robotics)
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Re: Surgical tubing stretched too far

Quote:
Originally Posted by nixiebunny View Post
We have a catapult powered with surgical tubing on our bot. The tubing is stretched from about 5 inches untensioned to about 20 inches as the winch pulls down the catapult arm. That's a 300% increase in length.

During the Hub City regional, we suffered from frequent decreases in shooting power and had to re-tension the tubing several times over the three days, and we ended up replacing some of it. I suspect that the tubing is being stretched past its elastic limit. It displays "stretch marks".

We can modify the bot's superstructure to allow for a much longer untensioned length on the tubing, reducing the extension from 300% to about 100%. Does this sound like it will solve the tubing over-stretching problem?
You'd probably need a stronger grade tubing since you'll get less energy stored with less extension (E=1/2kx^2). Unless you're modifying your superstructure considerably.