What's new
What's new

Excessive spindle runout BP 2J2 Series 1

Rprecision

Aluminum
Joined
Feb 10, 2007
Location
Denver CO
I am evaluating a machine and discovered some unexpected runout in the spindle.

When I throw a 1/2" end mill and collet in and indicate the stem up at the collet im getting. 0038-.0043" runout. Ok, ok I realize its not a gauge pin but in my other machines it spins at or less than .0005"

I have tried thoroughly cleaning the inside of the spindle, tried other collets, endmills, etc to no improvement. If I indicate about .100 inside the spindle bore I am getting .0025-.0029" I can't see any physical damage inside the spindle. Key looks well used but not obviously damaged.

I realize this is not good, is this usually the death of a spindle? bearings?

What else should I check next?

Thanks
 
How does the outside of the nose indicate, ideally checked as high and as low on the nose cylinder as you can. Seeing similar error there probably means a bent spindle (especially if the two readings are different or max isn't at the same rotation point), or a truly crappy bearing replacement was attempted and thoroughly butchered.

But if the bearings were that abused, I'd suspect you should be able to feel it when the Hi/Low is in neutral and you rotate the spindle by hand.
 
Check the spindle nose cap. It should be screwed to a snug fit. There is a set screw on the column side of the cap. Back this off before turning the cap. The two holes in the face of the cap are for a face spanner tool, usually 1/4" or 5/16".

The nut on top of the spindle shaft may be loose. This nut (some call it a Timkin Nut) draws the bearing and spacer assembly together to set the bearing preload.

Spindle - bearing inspection: The two spacers for the bearing I.D. and O.D. should be the same exact length to maintain the factory preload for the bearings. If not there will be spindle float.

John
 








 
Back
Top