Gunsmithing Spindle Bearing Adjustment

[wnroscoe]

With all the talk about indicating, pre-drilling taper boring and such I thought I'd share another topic with the masses, Spindle Bearing end play. Periodically I check for taper in my cuts and tail stock alignment and adjust accordingly. I thought it was time to check end play in my spindle bearings so I read up on adjustment. After running the lathe for 20 minutes I adjusting the bearing end play and pre-load according to the instructions. I checked the upward play on the chuck with a piece of stock in the jaws by lifting up with around 60-70 Lbs of force. The reading I got was .0006" to .0008" using a Brown & Sharp .0001" black face indicator. I felt this may be a little too much but found that South Bend specs for their 9" lathe is .0007" to .001" in the same test. My spindle spins smoothly with out excess resistance and after running the lathe for 20 minutes the main bearing cover and outboard spindle are warm to the touch. I thought I'd remind everyone to check this from time to time, maybe once or twice a year.

 

[300sniper]

Re: Spindle Bearing Adjustment

i need to get down to the shop and do some maintenance to the lathe when i get a chance. all the fluids need to be changed and i want to double check the level. i'll probably check out the spindle bearing preload at teh same time. i did check the spindle runout recently trying to diagnose some runout with my cheap chinese 3 jaw chuck. i was pleasantly surprised that my cheap chinese lathe had very little (>.0001") to no runout on any of the ground external surfaces of the spindle.