High torque that can be purchased.

[Trent B]

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.

[pfreivald]

"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.

[Dale]

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.

[Navid Shafa]

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!*

[Dale]

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

[DRH2o]

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.

[Mr V]

Originally Posted by Navid Shafa

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!*

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.*

[Hawiian Cadder]

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.

[Jeffy]

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.

[Dale]

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

[The Lucas]

Originally Posted by Jeffy

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.

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*.

[joek]

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

[11douglash]

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.

[couvillion]

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.

[gburlison]

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.