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Unread 22-01-2010, 12:48
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kmcclary kmcclary is offline
Founder 830/1015;Mentor 66/470/1502
FRC #0470 (Alpha Omega Robotics)
Team Role: Engineer
 
Join Date: Aug 2001
Rookie Year: 1994
Location: Ann Arbor, MI
Posts: 491
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Re: Cylinder damage with high kinetic energy?

Quote:
Originally Posted by vamfun View Post
Is this a concern for 2010 kickers?
[Paraphrased] A gal in [Bimba] support said that the cylinders should be limited to 20 ips independent of bore size used, and FIRST cylinders have no internal rubber stops to absorb energy....] So I'm thinking most of us are exceeding these limits and therefore should include external stops to preclude piston hammering. I'd like to hear peoples opinions on this.
A) 20ips is actually quite fast.
B) Yes, your mechanism should NOT allow the cylinder piston itself to be the stop. That can break the cylinder. Add an external stop, JUST before the stroke causes the piston disc to hit its end plate.
C) IMO, another solution is to just to
- use the cylinder to "[MaleChicken] a spring" to a catch (the CDF editor won't let me use the "Naughty Word" term! <lol>).
- disengage / back the cylinder off to its Rest Position.
- NOW release the spring with a second tiny cylinder (or other device), by pulling a pin.

A bit more fab and a control ritual, but it saves a LOT of wear and tear on your cylinder because it is not DIRECTLY involved in the firing of the device itself anymore.

- Keith
__________________
Keith McClary - Organizer/Mentor/Sponsor - Ann Arbor MI area FIRST teams
ACTI - Automation Computer Technologies, Inc. (Sponsoring FIRST teams since 2001!)
MI Robot Club (Trainer) / GO-Tech Maker's Club / RepRap-Michigan) / SEMI CNC Club
"Certifiably Insane": Started FIVE FRC teams & many robot clubs (so far)!
2002: 830 "Rat Pack" | 2003-5;14: 1015;1076 "Pi Hi Samurai" | 2005-6: 1549 "Washtenuts"/"Fire Traxx"
2005-(on): 1502 "Technical Difficulties" | 2006-(on): FIRST Volunteer!
2009-(on): 470 "Alpha Omega" | WAFL | Sponsor & "Floating Engineer" for MI Dist 13 (Washtenaw Cnty)
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