Hey! Does anyone know how much weight (roughly) a VEX rack and pinion can hold up? Would it be suitable for HAB lifting if the VEX rack and pinion gears were used with a CIM motor?
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I don’t have hard numbers for you, but I would never expect plastic Vex EDR gears to hold up an FRC robot. They’re simply not made for anywhere near that type of load.
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Look, I broke a Tetrix rack and pinion trying to lift a 15 lbs FTC robot, and that was with a metal pinion. You probably will strip both the rack and the pinion if you tried to lift an FRC robot with a system like that. I have decided that rack and pinions are not suitable for lifting anything heavier than 8 lbs or so…
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LOLL got it 
Hard hard hard no. I’ve broken those on Vex robots, much less trying to lift 150 lb FRC robots. I would look into other methods of linear motion, as rack and pinion is generally poorly suited to this type of thing.
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If you’re looking for powerful linear motion without pneumatics, the DART from Andymark would work nicely.
No, it will not hold.
If you want more information, check out this slide deck. The TL;DR is that by knowing the width, diametral pitch, and a few other easily calculable specs, we can calculate the bending and shearing forces that a gear can withstand.
We are planning on using 3/8 steel rack gears from McMaster. 14 1/2 pitch angle. We are looking at using 4 of these at the corners of our bot. Our calculations indicate that we should be well within safety range. Does anybody here have a different opinion on this plan?
Normally vex plastic gears and such don’t hold up to too much stress, especially when talking about climbing, so I’d say there are better options, like McMaster Carr stuff.
Team 6911 will be doing this too, just with 20 dp. Are you guys planning on driving wheels on the ends or getting into the platform in some other way.