Aligning the tailstock on a 9x20 lathe.

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Nov 13, 2010
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Of the few long'ish pieces I have tried to machine on my lathe, they have always had some taper to them. I have set the tick marks on my tailstock to "zero" but that has not removed it.

I have never been able to get rid of the taper in my 9x20 lathe. I certainly don't know how it is supposed to be done, but here is a method I tried today and I hope it will work.

I installed a MT2 holder with a brand new dead center into the chuck, and then I used my dial indicator to get it as round as possible. I got it to .001" TIR. I then placed an identical brand new dead center in my tailstock.

Using a high power magnifying glass and a piece of white plastic as a background I brought the two dead center points together at near touching but not quite. Then looking straight down as best I could I moved the tailstock over so that the points were perfectly aligned. As you can see by the tick marks, they are not on Zero anymore.

I hope this will make an improvement. I do not have one of those perfect and true machined bars to place in the chuck and then measure across.

So, do you guys think this was a good way to adjust it?




You just made that spotting tool. chuck it up and put it to use. It will give you a very good starting point.
Kmot, I have that lathe also. When I adjusted mine to center the marker was not lined up eithere. Mine (marker) shows to be off but the centers are point to point. ironman (Ray)
See the thread I started under "Tips & Tricks" - the guys came back with several ways of skinning this particular cat.

techonehundred said:
You just made that spotting tool. chuck it up and put it to use. It will give you a very good starting point.

Wow! Never would have thought of that! I would never have used it in anything but the mill. Doh!
Ken I said:
See the thread I started under "Tips & Tricks" - the guys came back with several ways of skinning this particular cat.


I will look for it Ken, thanks.
Nice tip Marv,

He did not make a set of buttons though. He left the stock he made the button with in the chuck so it remained true to the spindle. This way any 3 jaw chuck error is eliminated.

It seams to me a button set would only be useful with a 4 jaw chuck or a collet system.

Yes, you're right. I should have reread Frank's description before posting.

The trick is to make two buttons of the same diameter, each with a center hole. Put a center in both the headstock and tailstock with the buttons caught between the two centers. Now, a mike across the button interface will show the TS displacement. Actually, a calibrated fingernail can be used in place of the mike - human fingers are incredibly sensitive.
Regarding your "dead centers kissing" technique...I do something similar when rough aligning my rotary table under the quill of my mill...interestingly when I use a DTI to finish the job, I find the "dead centers kissing" technique usually gets me only within about .015 - .020. So as others have said, it gets you within range quickly, but probably won't take you all the way to where you want to go. I suspect one issue is that (inexpensive) dead centers are not necessarily absolutely concentric, and another is that the eye is only good down to several thousandths. At least...MY eyes.
My alignment method seems to have paid off. I also installed the scope to verify as suggested.

I just turned a piece of 1.250" brass into a burner port for a boiler and it came out very nice and straight. :)

Thanks for the link, Tin. US Army technical manuals are awesome! Thm:
FWIW you can put a dead centre in the tailstock and use a DTI with a magnetic base stuck to the chuck and the tip on the edge of the centre. Rotate chuck and get runout. It will give super accurate results but is a pain to see (mirror and torch job). Don't forget to lock the tailstock, and also check the centering when the ram is at extremes of position.

Best Regards

That's a great tip! Thanks for that Picclock, :)
Hey guys, I just obtained a coaxial indicator kit. I actually bought it to use with my mill but I saw that I can also use it with a lathe. So I tried it out today on my 9x20. Each tick mark on the gauge represents .0005" offset. I was able to fine tune the tailstock ram to only one tick mark. So for total offset I double that, correct? That would make my total runout .001"?

Is .001" TIR a respectable center to center setting? Or does it have to be a perfect .000"?

I guess this was the wrong question to ask. :big:

Anyway I found out, for anyone that may be interested, that the TIR on this type of measuring instrument is actually 1/2 of what is indicated. So in this case my TIR was .00025 which I will assume is good enough.
I'm having trouble understanding how the marks on a coax gauge can be assigned an absolute size. Won't the displacement indicated on the dial depend on the effective lever arm of the tip used on the coax?
mklotz said:
Once you get everything aligned, make yourself a set of alignment buttons so it will be easier to do next time. Here's Frank Ford's words and music about how to make them...

I just aligned my tailstock using the method in this link, and it worked great!!! Thanks for posting the link, Marv. I would be ashamed to tell anybody how much "out of spec" my tailstock was. I had aligned it 'By eye" about 3 or 4 months ago, and in a moment of insanity I loctited the adjusting screws. Today everything in my world slowed down enough that I was able to take the entire tailstock out to the main garage, fire up the oxy acetylene and get enough heat into things to soften up the loctite so I could remove the adjuster screws, clean off the loctite, and rejig things as per the link. It works fine now, and barely blistered the paint. ;D ;D ;D