Thread: Changing spindle bearings

You are checking drag torque, now your numbers make sense.
While perfectly valid, what Dad showed you was working numbers for his bearings on his machines.

There must be some gap on the clamping flange, .040 works just as well as .003.

Check the running temps, this is a b-port spindle not a 50 HP 8000 RPM 24 hour duty machine or something running .010 dia cutting tools 6 inches from the nose.
These are very low cost bottom of the line spindles, you are over-thinking this.
If it is tight and will not overheat it will work just fine.
Bob

Originally Posted by Winmac

He is my take on this,
The measurement of the gap is only to ensure there is a gap( at a minumin .003"). If there is no gap then the outer races are loose in the housing, free to spin, wobble and destroy fits. Not good, any adjustment of the preload spacers will require fitting of the retaining nut, machining of the shoulder to obtain a gap and/or re-drilling of the locating screw.

Winmac
I agree with you.
Robbie

Originally Posted by Winmac

Im far from an expert but i have a question about the stated axial pre load of 250lb this excedes whats recomended for a 7207c in the engineering hand books, light preload 150 N or 33lbs heavy preload 780N or 175lb
Was i wrong to state that brigeports use a light preload?

Were you able to get the machine up and running and were happy with the result?
Winston

Winston
Thanks for the smack on the back of my head...I just wanted to ask the membership that has the experience on the subject.
I'm pulling down the Fafnir book and read myself what their Engineer's recommend for a pre load.

Robbie