I just checked my tailstock alignment with my headstock and to my amazement, it is .006 to high. I could see it being a little low from wear but how do you adjust one that is already to high? Must I take the headstock loose and shim it or is there an easier way? I would hate fighting trying to get the headstock aligned again with the bed.
Dick
Did you check it with an indicator if you did read this.
"Dick" wrote in news:467f7a87$0$4643$ snipped-for-privacy@roadrunner.com:
Is it too high, or is the quill running uphill? Did you check it retracted, or extended to normal working length?
Scrape it! :-) Before you start, double check! Is there some dirt on the contact surface to the bed? Is there dirt where the tailstock is separated for taper turning adjustment? How does the reading change when you clamp the tailstock a bit/normal/a lot? How does the reading change with the quill retracted/out to the max?
A tailstock a few 1/100 mm (max. 0.04mm; *not* inches) too high is acceptable.
Nick
Interesting article . Now I need to check the droop in my cheapie dial indicator . Maybe my quill isn't .010" higher than my spindle after all !
What I did was to chuck up a .750 reamer, mounted a dial indicator on to it at the end nearest the tail stock, and then tightening the live center into the hole in the end of the reamer. I tried this with tailstock near the reamer and again with the tailstock extended. I also revolved the live center to different positions to see if it made a difference, it didn't. I then moved the dial indicator along the length of the reamer, (about 8 inch) and the indicator held steady. I also revolved the headstock and the end of the reamer ran within a .001 or so.
Dick
Has your lathe been leveled with a precision level?
John
I just went back and disassembled the tailstock. Although it was a little dirty between the upper and lower halves, there were no shims or any thing like that. I cleaned it up and tried all of my tests again but to no avail. All of the readings are the same..006 high and all else true.
I do a lot of deep hole drilling, .250 and .312 and this affects the straightness of the bores. I also use a steady rest quite a bit and I have a
1.375 roller bearing mounted and a number of collets made to run different tapered spindles for facing and drilling. Last week I trued up the bearing with the tailstock and noticed that the bearing was a little low so I raised it to be true with the tailstock. Since then, I have been getting a little chatter when trying to spot drill and the facings have not been dead nuts true. That is the reason that I got to checking the tailstock and found this problem.Dick
Yes, with a 10 inch master level.
Dick
According to Dick :
O.K.
You know that many lathe manufacturers make tailstocks a little high from the factory -- on the theory that the lathe will improve accuracy with wear for quite a while before it starts getting worse.
And for normal turning between centers, a height error of 0.006" should not make a perceptible difference in final diameter for anything large enough in diameter to make turning between centers practical anyway.
As for your deep hole drilling mentioned below (and snipped), you may need to start with the drills slightly under size -- and ideally finish with boring to final size.
If you *really* want to zero that offset, take the tailstock apart at the line where it spits to adjust for taper turning. Find which side is flat, and which has projections, and set the flat side up on a surface grinder and take off 0.005" or so (to leave it still a little bit high, so it does not immediately go into the "wear makes it worse" mode. :-)
Good Luck, DoN.
High tailstocks are more common then one would think. An old time machine rebuilder told me that it was fairly common, as it was a response to wear on the tailstock ways, over time.
Doesnt help the owner of a new machine much though..shrug
Ive seen em as high as .01 on Chinese machines. The owners wound up fixturing them on a surface grinder and setting them to rights.
Gunner
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