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Spindle bearings and alignment

chrisser All Messages By This Member #5758 I'm a long time from needing to do this, but I'd like to start accumulating any parts/tools I would need. My tailstock-side (right) spindle bearings are pretty tight - no detectable movement just using my hand.? But the change-gear-side (left) bearing has a lot of play. The left cap looks like it's been shimmed up, so perhaps removing the shim will help. I've read some old posts about shimming the bearing shells themselves and then scraping them to fit the spindle shaft again.? However, how do we maintain alignment of the spindle parallel with the ways horizontally and vertically insuring the spindle is centered in the bearing?? Seems gravity would have had a hand and the lower bearing shell is more worn than the upper, so that's probably where most of the wear is going to be.? I haven't measured the play but it seems like if I extrapolated it to the far end of the bed (like if I had a long rod chucked up) the far end would have significant up and down movement like maybe 1/8 of an inch (just guessing). Or do we just get the spindle centered as best as possible in the headstock and then adjust the whole headstock to align with the bed? Am I overthinking this?
Dennis Turk All Messages By This Member #5759 开云体育 Pull the shims out of the left hand bearing cap and see what you come up with.? You may find its fine.? I do have a long number 3 MT test bar if you need it.? You put this in the taper of the spindle then you can use an indicator to run along the top of the bar so you can tell? how parallel the spindle is with the bed.? I have checked a number of head stocks but never find them off enough to worry about. ? ? One other thing you guys need to think about and that is how you check the movement in the spindle bearings.? When using a test indicator you are looking for the quick snap of the needle as that is the clearance you have.? If you continue to apply pressure you will see the needle moving more but you are bending things.? Remember these machines are made of rubber.? Given very hard rubber but rubber just the same even cast iron moves under pressure.? Put a test indictor in the spindle of a Bridgeport type of milling machine? let the needle rest against the side of the vice.? Then just put your hand on the side of the head stock and apply pressure and watch the needle move. Sometimes given the flexibility of our machine tools I wonder just who we can do such precise work.? ?Dennis ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of chrisser via groups.io Sent: Monday, January 17, 2022 9:05 AM To: [email protected] Subject: [DaltonLathes] Spindle bearings and alignment ? I'm a long time from needing to do this, but I'd like to start accumulating any parts/tools I would need. My tailstock-side (right) spindle bearings are pretty tight - no detectable movement just using my hand.? But the change-gear-side (left) bearing has a lot of play. The left cap looks like it's been shimmed up, so perhaps removing the shim will help. I've read some old posts about shimming the bearing shells themselves and then scraping them to fit the spindle shaft again.? However, how do we maintain alignment of the spindle parallel with the ways horizontally and vertically insuring the spindle is centered in the bearing?? Seems gravity would have had a hand and the lower bearing shell is more worn than the upper, so that's probably where most of the wear is going to be.? I haven't measured the play but it seems like if I extrapolated it to the far end of the bed (like if I had a long rod chucked up) the far end would have significant up and down movement like maybe 1/8 of an inch (just guessing). Or do we just get the spindle centered as best as possible in the headstock and then adjust the whole headstock to align with the bed? Am I overthinking this?

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