Question About Headstock Alignment

If you have a .0001 dti, build the tools to check your bed first, then you know what you are working with. My rockwell was out .008, the new bed is .0006. Big difference in what your other measurements would be if the bed is out that much. Tim
 
DD, got the same problem, at the spindle using the test bar, it's dead on. At the end of the test bar I show 3 thou off. I leveled the bed and it didn't change so I ground the jaws. Didn't help. Can't figure it out. I have 6 levelers on the base, 4 on the head stock base and two on the tail stock base. There are 4 levelers on the bed at the head end and 2 on the tail stock end. I am only checking the Y axis though, not up and down. The problem is that if I chuck up a long bar, because of the misalignment, it will bend when the tail stock center is locked in to the end of the bar. You can see a visible out of round movement then in the middle of the bar. I always thought RDM was to check alignment of the tail stock to the center of the spindle. I also thought that grinding the jaws would cure the problem but it didn't. Comments would be appreciated. DD didn't mean to hijack your thread but since we both have similar problems I thought I'd add mine to yours to see what kind of answers we get. I'm leaning toward adjusting the levelers on the head end of the Lathe.
 
I have a Clausing late and if I put a precision ground shaft in the chuck and an indicator on the saddle and ran it down the shaft, by the time I got 18 inches from the check I was about .020 off. I found out that my whole head stock is adjustable. I could adjust it and it would take all taper out. Worked great.
 
Then turn the stock a quarter turn and try again. Does it stay true?
 
terryw123 said:
I have a Clausing late and if I put a precision ground shaft in the chuck and an indicator on the saddle and ran it down the shaft, by the time I got 18 inches from the check I was about .020 off. I found out that my whole head stock is adjustable. I could adjust it and it would take all taper out. Worked great.
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Hi, just curious, what model Clausing lathe do you have?
 
A few thoughts to end on.

Starting with the obvious. The spindle of the headstock rotates about its axis. We want the spindle axis to be parallel with the bed of the lathe and also in line with the bed ways.

The spindle will probably have a Morse taper machined at the chuck end. This Morse taper will have its own axis that may, or may not, be aligned with the spindle axis.

A: If the taper axis is parallel to the spindle axis but offset (we are talking the odd thou or so here) then it will be eccentric and a test bar mounted in the Morse taper will show the same circular motion at both its ends.

B: If the taper axis intersects the spindle axis but is not aligned with it then a test bar mounted in the Morse taper will show different circular motions at its two ends. But the motion will be in phase (the min and max dial indicator readings at the two ends of the test bar will occur at the same angular position of the headstock spindle).

C: The third case for Morse taper misalignment is a combination of the first two. The MT is angled to the spindle axis and does not intersect the spindle axis. In this case the motions at the two ends of a test bar mounted in the MT will be out of phase.

The best way forward is to disregard the MT and mount the parallel end of the test bar in a 4-jaw chuck and adjust the jaws to get a zero total indicator reading adjacent to the chuck. Move the dial indicator to the other end of the parallel section of the test bar and rotate the chuck noting the min and max readings. This is the Rollie’s Dad’s method.

The headstock should be adjusted to give equal min and max indicator readings about the zero at the free end of the test bar. After each adjustment of the headstock the end of the test bar mounted in the 4-jaw chuck should be zeroed before checking the free end.

Hope this is of use.
 
Thanks. Interesting as I've not thought about the MT and the spindle being two separate axis'.
 
I tried it tonight and the min max readings at 12" are virtually the same. About .00075" different. I was not able to get zero run-out at the chuck, ~ .0005-.00075. I also took a face cut on a 3" diameter piece and had maybe a thou movement on the outside.
I guess this means my headstock is in alignment.
Now if I could figure out why i'm cutting a taper when using center support.
 
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