greenbuggy
Stainless
- Joined
- Oct 6, 2005
- Location
- Firestone, CO
Admittedly I don't always know what I'm doing and can't pretend that I do, but what others do confuses me even more....
I bought a used 17x40 Howa lathe a few months ago. Haven't done much work between centers up until pretty recently, and have realized that the alignment of tailstock to spindle chuck was all kinds of wonky, and that drills have been walking and off center.
So I grabbed a DTI holder I made when I aligned the tailstock on my old lathe, and found that sweeping a dead center in the tailstock, my left-right alignment was within .0010, but up-down alignment was a tad more than .020 off.
So, I cleaned up the ways on the lathe a bit in case there was something there, put fresh oil on them, cleaned off the bottom of the tailstock, still .020 high. Thats when I noticed that there was a slight gap between the top and bottom sections of the tailstock, and after pulling it apart discovered a bunch of oxidized coolant and a pair of precision brand .020 shims, one at the front, and one at the rear of the tailstock base, aligned perpendicular to way travel.
Remove shims, suddenly I can easily get tailstock aligned to where my interapid says I'm damn close to "perfect" in both up-down and left-right planes.
My question isn't how to align the tailstock - I think I've got that covered. My question is, why would anyone shim up the tailstock that much? Is there a practical reason I just can't wrap my head around? My first thought was bed wear, but this lathe isn't worn anywhere near that badly, where it is worn is right next to the chuck (like most lathes, I think), and the ways that the tailstock rides on are in between the ways that the carriage rides on, and hardly worn at all.
I bought a used 17x40 Howa lathe a few months ago. Haven't done much work between centers up until pretty recently, and have realized that the alignment of tailstock to spindle chuck was all kinds of wonky, and that drills have been walking and off center.
So I grabbed a DTI holder I made when I aligned the tailstock on my old lathe, and found that sweeping a dead center in the tailstock, my left-right alignment was within .0010, but up-down alignment was a tad more than .020 off.
So, I cleaned up the ways on the lathe a bit in case there was something there, put fresh oil on them, cleaned off the bottom of the tailstock, still .020 high. Thats when I noticed that there was a slight gap between the top and bottom sections of the tailstock, and after pulling it apart discovered a bunch of oxidized coolant and a pair of precision brand .020 shims, one at the front, and one at the rear of the tailstock base, aligned perpendicular to way travel.
Remove shims, suddenly I can easily get tailstock aligned to where my interapid says I'm damn close to "perfect" in both up-down and left-right planes.
My question isn't how to align the tailstock - I think I've got that covered. My question is, why would anyone shim up the tailstock that much? Is there a practical reason I just can't wrap my head around? My first thought was bed wear, but this lathe isn't worn anywhere near that badly, where it is worn is right next to the chuck (like most lathes, I think), and the ways that the tailstock rides on are in between the ways that the carriage rides on, and hardly worn at all.