Rotation Systems

[Simon Strauss]

As Joel said above were were quite unsuccessful in our methods of creating a turret but i did see one quite interesting method at championships this year.

I forget what team it was or even if they were on newton with us but what i do remember is that they were a row or two behind us near the wall, and that they used sprockets layed out flat to function as gears. It consisted of one very large sprocket on which the actual gun was mounted which was then driven by two around 12 tooth sprockets mounted 60* from each other. ill try to figure out who it was and get a pic but if anyone else knows that would be great.

[Pat Fairbank]

We found an awesome lazy susan bearing at the local Reno Depot. It had a 12.5" outer diameter, and viewing from the top it had a 3/4"-wide fixed ring, encircled by a slightly higher 3/4"-wide rotating ring.

Our turret was all mounted on an extrusion frame, so we bolted that to the rotating ring. A Globe motor mounted on the turret drove a rubber cylinder against some belt we glued onto the fixed ring, for turret rotation by friction drive.

All the wires ran up through the middle of the bearing (the balls went in the front).

Here's a picture of the robot, if that helps make things any clearer.

[dtengineering]

We were quite pleased with our turret... it had 300+ degrees of rotation and about 45 degrees of tilt, and worked flawlessly all season.

If only the mechanism that loaded balls into it had done the same. Sigh.

In any case, we used an aluminum lazy susan bearing from Lee Valley Tools

http://www.leevalley.com/wood/page.a...50,43298,43316

The balls were loaded by a belt drive through the centre of the lazy susan.

Jason

Oh... yeah... we used a globe motor (with a 1" dia. pulley on it) to turn the turret using a 1/4" thick 15" dia. o-ring stretched around the outside of the lazy susan.

[UCGL_Guy]

We used a globe motor and #25 chain - we actually "attached" 25 chain around a lazy susan purchased from mcmaster carr to rotate - could have went 360 but we limited it to 180 just to be on the safe side. wires for the shooter CIM motor were tethered. We had no problems with this, our loader was also our demise. Anyway we used the same lazy susan last year for our arm and it worked really well.
Ken

[Andrew Blair]

Our original plan was to have a shooter on a turret, using a lazy-susan bearing from Mcmaster. Well, we got the shooter on the bearing, ran out of time, locked the bearing and eventually ended up just ditching the thing. But, the Mcmaster bearing was rated to a very high weight load, only 30 dollars, light, large ID, very tight for the price, and seemed very tolerant to side thrust. Very similar to the Lee valley bearing, and probably the same one UCGL_Guy's team used. Overall, nothing but good things to say about it, especially with a little weight on it.

[Astronouth7303]

Last year, we used an aluminium wheel hub for our arm. (I thought it was a great idea this year, too.)

This year, it was a turntable similar to what you would find at Home Depot for swing-out tables. (about 6"~8" diameter)