23-02-2011 20:44

Michael Corsetto

Re: pic: FRC971 2011

Aw man, why couldn't 254 bust those out a few days ago? Could have gotten some beauty shots of Optimus Lime...

Regardless, looking good guys! Have you managed to get that practice bot together? Is that what we're looking at here?

23-02-2011 21:20

roystur44

Re: pic: FRC971 2011

The picture is our comp bot before going into the bag. The practice bot is almost together. We are considering re gearing to make the rollers faster and elevator scary fast. The bot is rock solid.

Roy

23-02-2011 21:56

Tom Bottiglieri

Re: pic: FRC971 2011

I hear timing belt elevators are the future.

24-02-2011 15:14

roystur44

Re: pic: FRC971 2011

Definitely lighter than chain, less complicated than a worm gear, stronger than cord, more accurate and precise over a four bar arm. Designed right the timing belt elevator is simple to construct, very quick and durable and darn right cheap to build.


Roy

24-02-2011 16:00

sdcantrell56

Re: pic: FRC971 2011

What pitch belt did you use and how did you tension it? We started off with XL belt and ran into issues skipping it at start up. We finally switched to #25 chain and have had no issues since

24-02-2011 16:47

AustinSchuh

Re: pic: FRC971 2011

9mm wide 5mm pitch GT2. If you read the docs on the belts, the GT2 holds significantly more force before skipping than the XL. For our claw, we aren't tensioning it, and calculated the center distances correctly. For the elevator, there is a screw tensioner that pulls the ends together inside the carriage.

A 20 tooth XL pulley (1/4" wide belt) is rated to 4.6 in-lbs. A 20 tooth GT2 5mm pitch (15 mm wide belt) is rated to 93 in-lbs. An order of magnitude of difference. The two belts I just compared aren't exactly the same in everything but pitch, so the comparison isn't perfect, but it gives you a pretty good idea on why we chose the belt we did. Our elevator should be able to pick up ~100 lbs before the belts skip.

24-02-2011 16:51

sdcantrell56

Re: pic: FRC971 2011

Ahhh yeah GT2 is much stronger. Where did you guys buy belting that long in GT2 pitch?

24-02-2011 22:37

AustinSchuh

Re: pic: FRC971 2011

SDP-SI has it. It's a bit hard to navigate to, and I think involved a google search. We bought a 40 foot length of it (unfused), and trimmed that to length.