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Re: Rhino track failier?
Andy, I think Rhino customers really appreciate the open approach AM is taking to address this. I agree that a mold improvement is likely to solve the problem.
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Another approach, more in the quick-fix direction, might be to distribute the tension and shock loads on the pulley over a larger area. This might be accomplished by inserting a tight fitting sleeve (maybe aluminum tube) through the pulley bore (0.96 inch), and then sleeve type bearings (maybe oil-lite bronze) into the ends of the sleeve to accept the 3/8 inch bolt spindle.
I have ordered some pulleys to try this, along with aluminum tube and bronze bearings. Tube and bearing part numbers from McMaster-Carr are 9056K28 and 6338K465, respectively. I plan to turn the tube O.D. for a tight fit to the pulley bore, then bore (drill) it to a tight fit for the 5/8" bearing O.D., and face to 2.175" long. After a light press to fit the tube into the pulley, the bearings can be inserted and then the assembly should replace a damaged one. I don't know how much extra friction the sleeve bearings will add, relative to the 1416ZZ ball bearings -- current draw will tell that tale. If this approach works it might be used to repair damaged pulleys.
I am just an electrical engineer fiddling with mechanical things based on FRC experience. I would appreciate critique of this idea, especially from those with stronger Mechanical Engineering background and/or more FRC design experience.
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Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
 since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)
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