although in a pinch, the tubes that are just bigger than a 1/8" shaft will work just fine. A little more drag, but then my problem with drives is getting DOWN to speed, not going too slow, nor running low on battery power. My I-boat had the tube shafts when I got it, and it's been battling for >10 years. That said, the kind with bushings aren't very spendy, either.
Go down to the hobby shop or hardware store, browse the K&S rack. Use your shaft-size rod as a starting point & see what fits by simple test-fitting. K&S tube sizes (I believe they're OD) from their web site are: 1/16" 3/32" 1/8" 5/32" 3/16" 7/32" 1/4" 9/32" 5/16" 11/32" 3/8" 13/32" 7/16" 15/32" 1/2" 17/32" 9/16" 19/32" 5/8" 21/32" Each fits snugly inside of the next-larger size, i.e. 11/32" fits inside of 3/8", etc.) which would make the wall thickness 1/64". JM
Just to be sure, slip the shaft into the tube while in the store, to check for fit. But yeah, that's how it works
Then go to Small Parts (http://www.smallparts.com/). They list OD & thickness, so you can pick what you need. You might have to order enough to satisfy a minimum, but it's not hard to find stuff that you'll use eventually. JM
