Originally Posted by BEARINGMAN  Leeway
you sugested eccentric collar bearings (usually Fafnir (now Timken)) but they should only be used for non-reversing loads. What you should use here is Sealmaster($$$$) McGill, or Dodge with the squeeze-lock collars. The eccentric will come loose with the inertia of the reversing load, where the squeeze-lock type grips evenly around the shaft and won't come loose. |
You are correct of course. No where near optimal and not normally good for CNC. I use a bearing on both ends of my X a=on my router. I locked them both and was getting issues with the lazy end coming loose at the collar. I pulled the collar and used a couple wave washers between the journal and the bearing and I no longer have the collar on the other end loosening up.
On my Y axis, I use the same type bearing, but flange style. The other end of it though is a bronze flanged bushing also with wave washers. These have to be adjusted periodically and are not maint. free, but induce only little play and within my tolerances. For the ease of installation and low initial cost, I feel it was a fair trade off.
I had intended to build new mounts with proper bearings and will likely do that now that I have my mill running, but it's not critical for me right now because it is working so well. The most play I have measured on the router after it was tuned was .008" and that was before I installed the second ball nuts.
Here is a link to
pillow blocks. These don't have the eccentric collar and would like work well with a set screw inserted into the screw.
Here are the
flanged type I used.
Here are the
4 bolt flange type.
If you have plenty of screw and room, you could mount the flange bearings back to back on a plate with a spring in between and would have a decent setup.
One other thing, since you won't be turning journals on the screws, you can lock these bearings in place on the shafts using a locking nut configuration on both sides. 4 nuts total. Takes some real estate, but works pretty well.