Alignment check

rock_breaker

H-M Supporter - Diamond Member
H-M Lifetime Diamond Member
Joined
Dec 31, 2010
Messages
937
I was asked to check for a bent quill/spline shaft from an unknown brand of drill press given to my son in-law. After cleaning in the solvent tank I put it between the centers on the lathe; the splined shaft end had a centering hole and the jaws in the 5/64 - 1/2" chuck appeared to be open equally. The splines near the headstock have 0.002" TIR and at the middle near the upper quill bearing the same. Running the indicator lengthwise on the splines gave a 0.001" runout on one, but nothing on the others. After relocating the indicator to the spindle much the same type of readings exist. After returning the assembly to him today he told me the chuck started wobbling when the quill was extended about half way. My assessment is bushing wear or damage in the housing holding the quill. Is there something else that cold cause this problem?
Thanks for the help.
Ray
 
Spindle bearings or drive sleeve bearings would be my guess. Both can cause run out. The fact that it happens with the quill extended half way suggests the drive sleeve bearings would be the first suspect. It could also be the drive sleeve itself if it is worn but this is not a precision piece so I doubt it is worn enough to cause wobble.

Remove the belt and turn the front pulley by hand and measure the run out inside the spindle taper. If run out is excessive (greater than maybe 0.001-0.002") then the spindle bearings need replacement. Then grab the spindle and push/pull on it. If you get a lot of run out then the drive sleeve bearings are shot.
 
Thanks Mikey.
As I said he handed the quill and drive shaft assembly to me so it will have to be reassembled to check the taper. He did say when he got the machine it looked as if someone had pounded on it with a hammer and he had put a different chuck in it but it still wobbled. The drive sleeve and rack look good, 0.001" taper.

The spindle bearings were difficult to turn prior to the wash tank , but quite smooth afterwards. While the assembly was in the lathe I pushed and pulled the shaft at midpoint with no deviation on the indicator. As you have pointed out the problem is probably in the sleeve bearings, I will ask him to remove them for examination.

Thanks again
Ray
 
Back
Top