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Re: Dual CIMs and #25 Chain
Quote:
Originally Posted by dtengineering
The dual CIM's didn't fail... your chain and sprocket failed.
Had you switched to #35 chain and sprockets... well... who knows what could have happened. We used #35 chain and aluminum sprockets for years and never had a problem. In fact our Breakaway 'bot, with dual cims and a 14:1 gear ratio, just spent two days of continuous driving doing demonstrations, has given "robot rides" to people weighing well in excess of 200 lbs, and can still climb ramps in excess of 45 degrees. The chain and sprockets show no signs of wear.
However... looking forward... use the largest sprockets that you can. The larger the sprocket the less the load in the chain, and the more teeth on the sprocket to transfer the load.
Also consider always having one wheel on each side direct drive. Get the extended shaft for the toughbox, and the keyed mounts for a wheel, and bolt that wheel to your gearbox's output shaft. No matter what happens to your chains you'll still be able to move. Our drivetrains have been 100% reliable since we shifted to direct drive.
Jason
P.S. Our drivetrains have been 100% reliable... but during Lunacy we had an unexplained control system breakdown in the quarter finals at Seattle... which adversely affected our alliance, captained by a then rookie team 2898. It was an awful way to end the weekend... little did I know what it would take to get someone to investigate FMS reliability issues.....
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We do plan on trying to switch to direct drive. We want to prototype that this summer.
Another thing I have done for this years demos is make it so only 1 CIM is enabled until we hold a button on the controller, which is when the 2nd CIM is enabled. This will both reduce the stall torque on the chain, and make the drive less jumpy.
And that rookie team is now having issues this year 
__________________
All statements made are my own and not the feelings of any of my affiliated teams.
Teams 1510 and 2898 - Student 2010-2012
Team 4488 - Mentor 2013-2016
Co-developer of RobotDotNet, a .NET port of the WPILib.
Last edited by Thad House : 03-05-2012 at 02:10.
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