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Unread 11-02-2007, 22:05
Justin M. Justin M. is offline
Mechanical/Driver
FRC #0321 (RoboLancers)
Team Role: Mechanical
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Philadelphia, PA
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Re: Redesign, 36mm question.

Quote:
Originally Posted by Stud Man Dan View Post
http://www.chiefdelphi.com/media/photos/26796

5' long arm 2 banebot 36 mm motors, However we we are using 125:1 gearboxes with a futher 6:1 on chain.

This was done for speed tho, and torque was not the factor.

It lifts the arm no problem, back drive was a small issue but we made some modifications and now it stays where ever we put it.

If your wondering about torque, these motors can handle it. The gearboxes are something to worry about potentially, but we've been running it for about a day and not seen any of the problems that other people have been seeing. Its run enough for me to be happy with it. ( Maybe 200 cycles up and down? )

The arm weighs ~7.5 lbs with tube in tow. Its displaced over the distance of 5' b/c the pvc is like .75 lbs a foot or something, but the gripper ways ~ 2 lbs and the tube ~ 1lb.
We are at the same weight, just about. The arm is actually going to be made of 80/20 1515 , I just modeled it as normal aluminum square tubing for sake of simplcity in seeing my design. The one 5' piece of 1515 weighs 6.7165lbs. (based on the 1.3433lbs. per foot given in the catalog), and our claw, by my guess, weighs maybe 2lbs, also made from the 1515 extrusion - so realistically, we are looking at ~9lbs. I just said 15lbs. as an overestimate - tomorrow I'll actually weigh everything out so I can have an accurate sense of how much this thing actually weighs.

I'll probably just put an order in tomorrow for a 2 72 tooth sprockets from IFI, and have them next day aired, just to play it on the safe side, 11:72 should be more than enough to lift this thing. I think we have some 60 tooth steel sprockets laying around our storage room somewhere, and we also have the 3/8" bore 11 tooth sprockets for the motors themselves, so I'll put those together real quick with those other sprockets and see if it works.
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