RF30 spindle bearing preload sanity check

[Makintrax73]

Guys I'm going through my mill doing some maintenance. I have an RF30 knockoff. It has a two collar preload system with very small divots in the collars which I assume are for drifting with a small drift and hammer. I loosened the locking collar and tightened the preload collar with the belts off. It was rather easy to tighten, and because of the small size of the divots it is VERY difficult to overtighten it (I think) simply because the drift with pop out of the divot if you hit it with any real force.

I noticed a very small amount of increased force to turn the spindle. It still spins easily. I ran it at 900 RPMS for 5 minutes. The upper bearing did not heat up at all. The lower bearing warmed up to above room temp, but it was warm, not hot to the touch.

Is there a rule of thumb for mill spindles? I assume the answer is tight, but doesn't get "hot" when you run it? How long should I run it and what speed to check for it getting too hot?



Thanks!!

 

[benmychree]

The "little divots" are for a pin spanner.

 

[Manual Mac]

Check under the RongFu sections,
I remember mikey was a wealth of knowledge on RF30/31 machines, & remember him addressing this subject.

 

[Makintrax73]

Check under the RongFu sections,
I remember mikey was a wealth of knowledge on RF30/31 machines, & remember him addressing this subject.

I think I found it: https://www.hobby-machinist.com/threads/spindle-bearing-replacement-for-the-rf-31-mill-drill.49002/

As these bearings do not have a specific preload value I just snugged the first nut very firmly with a spanner and a spindle wrench and engaged one of the washer tabs. The second nut is firmly tightened down on top of the first one and the spindle is complete and ready for installation in the mill. The Luminar 28mm spindle wrench held the spindle solidly while tightening the preload nut and I can recommend it.

LOL. Maybe I am just being nervous I was hoping for more detail than that!

 

[stupoty]

If you have the pulleys off it should turn easily but not spin much if you give it a spin by hand.
or try eliminating end float and then an extra 1/4 turn and feel if its still freely turning.

As you checked for, if you go to tight it will warm up "to much" when you test run it.

Stu