[Andy Baker]

This is a good design. It needs some improvements, but it not too many.

1. Urethane rollers are good. Wildstang uses that materials in their "bupods". I am not sure what durometer to use, but try 50a (soft), 60a, or 70a (harder).

2. The gap between the rollers and the aluminum plates does not need to be as much as you show. I suggest a 0.02" gap on either side of the roller at the most.

3. The pockets for the rollers need an inner radius, if you are going to machine this with a CNC mill. A 1/8" or 3/16" radius will work fine. When you make this inner radius, you may need to make the pocket deeper so that the roller still clears the aluminum (that was a problem in the early versions of the 6" AndyMark trick wheel this past year). Also, the outer corner needs a small radius, in order to not dig into the urethane roller.

4. 5 screws holding the two plates together is a low number. You really don't know what kinds of loads this thing will see... it will get banged from the side, and it will see many dynamic loads. I suggest doubling the number of screws and moving them out, away from the center. Also, if you use an even number of screws, you can fasten them without nuts by having every other hole be a tapped hole.

5. The bore either is designed for a driven shaft (keyway, trantorque, etc.) or a bearing (driven by a sprocket). If it is a keyed shaft, the keyway in those two plates will get stripped. If you want to drive this with a shaft your keyway will need more face width. You can do that by adding a bolted-on hub. If it is driven by a sprocket, that can be bolted on in the same manner.

This is the start of a good design, Matt. I like the simplicity of two plates. Also, I applaud your courage for posting this (and other) design. Keep up the good work!

Andy B.