Why Can't I get my DTI to Repeat

ddickey

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Apr 21, 2016
Messages
3,566
Checking run out on a part on the lathe and/or dialing in an adjust-tru type chuck or 4JC. Lathe in neutral I rotate by hand. After adjusting and getting what I think it within a thou the Indicator will not repeat to zero or high spot and low for that matter. Start at high spot zero the indicator rotate come back .0015" higher next rotation 001" low. change indicators same thing. change holders same, try the tenths indicator same. I'm beginning to wonder if it is the lathe. Maybe a bearing problem? I have no idea and it is frustrating. Spindle rotates freely and no noise. A little heat after high rpm's but nothing out of the ordinary.
Anyone else have a similar problem?
 
Try levering the spindle up and down with an indicator at the top to see if the spindle bearing is loose.
 
Chuck loose on the spindle? If you had not said that multiple indicators did the same thing, I'd have thought a loose hand on the indicator.
 
No it's tight. Yeah I tried five indicators and three holders.
 
Are the face bolts tight on your adjust-tru? If you are using your indicator in a tool holder, maybe try locking the slide gibs and tightening your tool post stud to eliminate any possible play?
 
How is the axial play? Chuck up a 3/8 rod, grab the other end with a tail stock drill chuck. Monitoring the face of of the chuck while you crank the TS handle back and forth and see what kind of play you have.
 
Can't tell cause I can move the TS even locked down. If I had to estimate less than .0005"
 
Is the tailstock being used?
 
Back
Top