Four-bar joints

[HarveyAce]

What would a cheap solution as to what to use for the axle hinges of the joints of the robot? all we have is the kop and no money... oh, and hardly any equipment... we are using the gearbox with chain to the top shoulder joint with a sprocket, with another small banebots motor for a claw. do the bane bots use jags, or could we use a spike relay?

[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.