Four-bar joints

[2611.Shooter]

You can run them off of a spike. however, if you need variable speed, it may be smarter to run them off of a vector motor controller. they are cheaper than the jaguars, but still provide fine control. hope this helps.

[548swimmer]

Instead of purchasing bearings or nylon, you could glue in some pieces of PVC pipe. It's not quite as low friction as nylon, but with enough grease it should work!

[Dad1279]

We have used tubing/bolts, etc through a hole drilled in 1/4" lexan.

For heavier joints, you can use the bolt as an axle, and use a bronze bushing in a piece of aluminum. Bronze bushings are cheap.

[MrForbes]

A steel bolt going through any kind of metal or plastic or wood will probably be adequate for a pivot bearing. Make sure the hole is just a little bit bigger than the bolt, perhaps a few thousandths of an inch up to 1/64 inch bigger.

Please read the robot rules in the FRC Game Manual

http://usfirst.org/roboticsprograms/...nt.aspx?id=452

which are very specific about what device you have to use to power the motors. Some motors can be driven with a Spike relay, others require a Jaguar or Victor speed controller.

[IndySam]

Contact some local teams for help. I know if you were in my area we would gladly help you out with parts or what ever you may need.

[Jeffy]

Many teams have used PVC pipes with T connectors on the ends for their arms. Inside the T connectors you will need an endcap each end that will connect the smaller diameter axle to the pipe, or a bushing to the pipe.

These can be made on a lathe, but I'm guessing you don't have one. This is the first year we have one.
Here is how we have done it in the past-
1. Buy a hole saw that's interior cutout is the size you need, or slightly larger than needed. A bit larger is likely what you will find.
2. Cut out as many of endcaps as you need from 3/4" red oak. Do not use plywood or MDF it will split.
3. Carefully line everything up and anchor each piece and enlarge the hole to the size disired.
4. Use a bolt and nut to compress the endcap
5. Put the bolt in a drill press (or properly anchored hand drill) and use a file until it is the size you would like.

Hole saws can be found at nearly every hardware store.