Re: High torque that can be purchased.
 

Based on this thread it looks like surgical tubing follows Hooke's law until about 300% elongation (that would be 4x the starting length) then it starts to become more exponential in shape.

Re: High torque that can be purchased.
 

"Doesn't suffer permanent deformation" and "follows Hooke's Law" are not the same thing. To be honest, in most robotics applications, I doubt it matters much, but the distinction could matter in some way to somebody.

Re: High torque that can be purchased.
 

We used a BaneBots P80 144:1 transmission driven by a CIM with and additional 4:1 of chain reduction. The P80s seem much more robust than the P60s. That design got us though two intense regionals, including the Oregon Regional with you folks, and we never had a single problem.

That did mean we needed to use our 775s as the second motor on our Supershifters, along with a CIM on each side, but that also seemed to work out just fine with the CIMulators.

The thing we've learned along the way is FPs, and I assume 775s, really don't want to be run at low RPMs or close to stall where as CIMs don't seem to mind (much). In 7 years of doing FRC we've never burned out a CIM where as we have buckets of fried FPs and the like. I'd also avoid Banebots transmissions above 144:1 unless you are sure you won't exceed their tourque specs.

Re: High torque that can be purchased.
 

I'd be curious to see how you designed the disc brake. We remembered that we saw a few on other robots in 2008 and we designed a system this year using a Tolomatic pneumatic disc brake. Unfortunately we figured out in Q&A that it wasn't legal, since it wasn't "A pneumatic cylinder". It was a mechanism with a cylinder... But I digress.

So, did you design your own system with a ready cylinder or find some legal COTS alternative?

*By the way, Loved playing with you guys! Your team is always friendly, gracious and certainly a force to be reckoned with. Great showing this season!*

Re: High torque that can be purchased.
 

Most teams using disk brakes use Minibike, pocket bike or bicycle disk brakes and then just attached a pneumatic cylinder with a 1 inch stroke or so. You just buy the disc and a caliper and go wild. Here's a sample vendor but there are many out there. http://www.partsforscooters.com/All-...ke-Brake-Parts

Re: High torque that can be purchased.
 

Team 1598 is using two toughbox transmissions mated together. They are edge to edge using aluminum angle to hold them together making them one unit. We made a custom input shaft for the second one that is 1/2" hex milled to 3/8" hex that fits the 14 tooth small cluster gear from andymark. We drive from 1 to 2 with a chain ( allows easy ratio change with sprocket change ). We are 2:1 chain driving ours because of design, but could direct drive also. It is driven with one cim, and works great with no counter balance.

Re: High torque that can be purchased.
 

I assume that was directed at me or more particularly our team #2046. As the other poster stated it is a bicycle disc brake caliper. We made our own rotor out of aluminum to make it in a diameter that fit in the space we had, and to have a mounting pattern we could work with. To actuate it we used a 1" stroke cylinder that we made a custom piece to accept the ball on the end of the cable. Stop by our pits in St Louis for a close up look.

* Back at ya, we always love playing with the Skunks, we learned a lot of our ways from you guys.*

Re: High torque that can be purchased.
 

http://www.andymark.com/ProductDetai...ctCode=am-0141

this is the only off the shelf product that will do it with no modification that i am aware of.


in 2007 our robot had a 144-1 p80 into a 12-44 sprocket reduction, and then another 12-44 sprocket reduction. that did not end well.

Re: High torque that can be purchased.
 

Has anyone considered using a p80 gearbox and a CIM-u-lator together? The max torque reccomendation on the p80s is much higher at 85 ft-lbs.

It looks like a viable, but heavier option. From what I hear, you better support the other end of the shaft though.

Re: High torque that can be purchased.
 

Yes it is vital to support the end of any BaneBots transmission shaft. You'll burn through many a transmission if you don't.

Re: High torque that can be purchased.
 

We use 2 RS-550 motors on a CIM-U-Lator connected to a P80 gearbox for our arm. We do support the end of the shaft and haven't had any issues *knock on wood*.

Re: High torque that can be purchased.
 

we used an RS-775 motor through a 256:1 gearbox, with a 1.5" sprocket on the drive end, run to a 48 tooth ANSI 35 sprocket am-0055/am-0224 (6" nominal) with another 6" floating in the chain holding it tight; and we still had to put surgical tubing on the back. our robot

Re: High torque that can be purchased.
 

If you're willing to go with 2 cims on your drive train, there is such a thing as a 256:1 plantetary gearbox for one and even two cims.

Re: High torque that can be purchased.
 

We used a RS-775 and a 256:1 gear box, with a worm gear giving us another 20:1 reduction. We experienced problems with the worm and worm gear chipping but not with the planetary. I believe that the worm gear was useful in protecting the transmission from the shocks of bumps on the field. We lacked a way to reposition the arm on the field however.

Re: High torque that can be purchased.
 

We achieved 1600:1 reduction by replacing the output shaft of a 256:1 banebot planetary with a modified 8 tooth stem pinion mated to a 50 tooth toughbox output gear. Not an off the shelf solution, but very compact package as we also incorporated an encoder mount to measure the angle of the arm.