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.
I should also point out that customer service for all these companies is great about replacing parts that don't measure up. But in the world of FIRST robotics, returning bad parts for good ones is not an acceptable option during build season. Getting good parts from a supplier the first time can make the difference between getting your robot built early, having time to practice with it, leading to a great season, and finishing your robot in your pit at your first regional.
|
We will check around for all of out products but the AM shaft does states on their website with the .5" hex shaft "This dimension is slightly larger than the bore for the 500 Hex Hub and 1/2" Hex Bearing. In order to make this material fit into the hub or bearing, we suggest that the user slightly modify the hex stock. We have found that the best way to do this is to use a belt sander and carefully sand off a small amount of each side of the hex stock until the stock fits into the Hex Hub or Hex Bearing."
small tolerances are manageable but this was just not working out for us.