07-03-2016, 10:36
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no bag, vex only, final destination
AKA: Pinecone
 FRC #0228 (GUS Robotics); FRC #2170 (Titanium Tomahawks) Team Role: Mentor
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Join Date: Dec 2008
Rookie Year: 2006
Location: Glastonbury, CT
Posts: 7,737
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Re: We only need half of this right?
Quote:
Originally Posted by Kevin Sevcik
We did that on our input arm. MiniCIM into a 30:1 VP, into a 20 tooth pinion mated with a 64 tooth gear on the arm. The miniCIM + VP is very close to shearing a tooth at stall. When you backdrive the mechanism by dropping the arm on top of a divider with the weight of the robot, it shears teeth before backdriving.
Our solution is a lot of work for me. We're switching to steel 10DP gears, that I have to machine down to the same face width and with a versakey pattern. If that doesn't work, we're switching to a set of the same steel gears I'm leaving at the full 1" face width. That should move the failure point to the output shaft itself.
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Why not "just" switch to 35 or even 25 chain? Gear drives for arms are going to have this problem a lot just because the full load of the arm will be carried by just 1 or 2 teeth at a time, versus several wider teeth in a chain setup. Learned this lesson the hard way in 2013 and 2014.
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College Mentor: 2791 (2010-2015)
-- 2015 TVR Motorola Quality, FLR GM Industrial Design -- 2014 FLR Motorola Quality / SFs (with 341, 4930)
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