Quote:
Originally Posted by ToddF
We don't have experience with the VEX bearings, but do have experience with AM hex bearings. This fall we converted our summer developed dead axle WCD to a live axle design, using hex axles. We ordered a bunch of hex bearings from AM for our bearing blocks. We found them to be frustratingly undersized. We are using standard 7075 1/2" hex extrusion for our axles and AM hex output shafts to direct drive the center wheels. We found that the AM bearings didn't even fit their own hex shafting. This led to hours of hand working the hex shafting to get everything to fit. Using a belt sander to resize the hexes resulted in scrapped axles from taking too much material off.
For our build season drive train, we ordered hex bearings from WCProducts. Whereas in the AM order, 2 of the 14 bearings fit our shafts, in the WCProducts order, 2 of 24 bearings are undersized. Most slide right on our shafts, and if they are snug, a few swipes over sandpaper to get the shaft faces planer (extruding leaves high spots in the faces) gives a good fit.
So, if you are having problems with AM bearings being too tight, or VEX bearings having too great of runout, try the WCProducts bearings. If we had not done so, we would probably abandon hex shafting as too labor intensive a system to be truly useful.
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Todd,
I am sorry about your troubles with the hex bearings. You will have the same troubles with VEXpro hex bearings as we decided to make them the same nominal size as the AM bearings. WC Products decided to make their bearings larger to accommodate the standard hex shaft.
We chose to solve the problem differently. Standard hex shaft as a really large tolerance of almost +.005". Practically most shafts come in at +.003". We decided the shaft was the problem so made a custom hex shaft that is sized appropriately to fit in both the AM hex bearing and the VEXpro bearing both in 3/8" and 1/2".
I can't really speak for WC Products or AM, but we made a conscience decision to make out bearings the same nominal size as the FRC industry standard.
Paul