Ball Bearings on PVC

[Richard Wallace]

608 bearings are 22mm (about 0.866 inch) outside diameter. They are among the worlds most commonly used bearings, as skateboarders everywhere will attest.

3/4 inch schedule 40 PVC pipe is about 0.804 inch inside diameter with about 0.113 inch wall thickness. So if you can bore the pipe ends out to suit the 608 bearing, you'll have about 0.08 inch wall thickness remaining. Should be strong enough assuming you aren't loading the pipe heavily or supporting a very long span.

[edit]A convenient feature of 608 bearings is their 8mm inside diameter. This makes them useful with metric M8 or unified 5/16 inch bolts as spindles. When used in small electric motors, 608 bearings can support either 8mm or 5/16 inch shaft extensions easily, because there is only 0.002 inch difference between those sizes.[/edit]

[MrForbes]

also 1" OD 1/16" wall round aluminum tubing is pretty common at hardware stores, has 7/8" ID, and you can find FR6 bearings, with a 3/8" hole and 7/8" OD, on the internet and at our favorite robot parts suppliers such as AndyMark and Innovatin First Inc.