Thread: Tailstock Alignment Considerations

Originally Posted by michiganbuck

One simple trick is to turn a part to a point in a chuck or collet and then bring the tail center to eye-ball view a match.

Yes, this only gives the match at that one place along the bed..
Another simple test is to set the tailstock on a surface plate to see it is flat or not flat, and if the quill is out of place/straight. .
Good to consider the tail may be wore some as well as the bed, so caution to making changes.

A Point! thanks!

Turned a point! I have the TS extended 5 inches and the misalignment is pretty obvious.



I put a scale up behind these two mismatched points and my old eyes tell me that the TS is .025 low.




So I am thinking I am cleared to shim that forward side of the TS to make up the .001/in dip over the 10 inches of the Test Bar. I read .010 of wear over the length of the test bar with the indicator on my saddle.


So that is a little interesting to me. I am looking for an improvement not "necessarily" perfection here. I have made a lot of things with the lathe before I even noticed but it clearly needs a little attention.

I should plan to shim both ends of the TS? yeah? .025 on the quill side should bring these points together. But what about on the far end? Would that be .024 to account for the dip in the test bar? (.001/inch)

It gets confusing to me since there is surely bed/saddle wear too.

Be sure to test with test-bar or a good taper blue feel into a good blue to fit in the TS taper.
Caution because you are dealing with the expected TS front end wear, and with some more wear at the whole bottom.
Consider that the TS was near dead flat at manufacturer/new so see what by shim testing would make it flat perhaps testing on a surface plate, *Yes the quill being at height and flat.
Then with more shim testing figure what would make TS to the height of the headstock (quill)perhaps need .002 or .010 more (?).
This to let you know within a thow or two what would make it right for flat and then height.
Then evaluate what wash-out/wear you have in the bed and target the best TS height for most of the use of the lathe and add that to your target height.

QT Ricard [If you don't scrape you can order some "Phenolic" from McMaster Carr and epoxy the shim to the top of the bottom 1/2 even if the front shim.]
And a decent SG grinder hand could get (grind) this ("Phenolic") within .001/.0015 with grinding.

Yes you would test it to know the amount front and back to tell the grinder hand the needed take.

Originally Posted by michiganbuck

Caution because you are dealing with the expected TS front end wear, and with some more wear at the whole bottom. Be sure to test with test-bar or a good taper blues into a good blue to fit.
Consider that the TS was near dead flat at manufacturer/new so see what by shim testing would make it flat perhaps testing on a surface plate.,
The with more shim testing figure what would make TS to the height of the headstock.
Then evaluate what wash-out/wear you have in the bed and target the best TS height for most of the use of the lathe.

I like the surface plate idea but my granite one is too small for the job. I have a 16" lathe face plate that might work. It's a very clean SB survivor? hmmmm

Originally Posted by Kevin T

Turned a point! I have the TS extended 5 inches and the misalignment is pretty obvious.
I put a scale up behind these two mismatched points and my old eyes tell me that the TS is .025 low.
So I am thinking I am cleared to shim that forward side of the TS to make up the .001/in dip over the 10 inches of the Test Bar. I read .010 of wear over the length of the test bar with the indicator on my saddle.
So that is a little interesting to me. I am looking for an improvement not "necessarily" perfection here. I have made a lot of things with the lathe before I even noticed but it clearly needs a little attention.
I should plan to shim both ends of the TS? yeah? .025 on the quill side should bring these points together. But what about on the far end? Would that be .024 to account for the dip in the test bar? (.001/inch)

It gets confusing to me since there is surely bed/saddle wear too.

It's a used lathe with wear. Give up on getting it perfectly correct, everywhere.
Start by putting the tailstock where you use it most (think drilling) and check the height error there.

Put shim between the two sections to make that zero. You may find that the naturally-occurring wear on the front of the
tailstock gives you a further low reading if the quill is extended. So then you may want to reduce the shim at the backside
a bit and boost it up on the leading side.

If you can drill an accurate center hole with a number zero or number one centerdrill, you are done. Use the lathe to make chips.

Qt; [I like the surface plate idea but my granite one is too small for the job. I have a 16" lathe face plate that might work. It's a very clean SB survivor? hmmmm]

likely if you get it within .005 where you use it most you will be able to do very good work.

Buck, you can zero the indicator on the tailstock side and if you have one on the top too. then losen the TS and move it down a foot down the bed and lock it and then move the saddle down to that location. being sure not to move the indicators and check the TS in that spot and continue down the bed checking along the way. I suggested buying a Micrometer to get an exact measurement of the quill to turned aluminum. A veneer would work, but most machinists have micrometers.

Originally Posted by Kevin T

I should plan to shim both ends of the TS? yeah? .025 on the quill side should bring these points together. But what about on the far end? Would that be .024 to account for the dip in the test bar? (.001/inch)

It gets confusing to me since there is surely bed/saddle wear too.

Short answer yes you will shim both sides, but different thicknesses to both raise height, and get parallel. I'd set a goal for inside of .002"-.003". Don't worry too much about test bar dip yet, your not fine tuning that hard yet.

Longer answer : Let's figure some common terms. As front usually refers to front of lathe. We'll say quill side(TS spindle), and hand wheel side(TS hand wheel). You may end up with shims on four corners, but on a TS you want to keep shim thickness even on front and rear of quill side, and keep shims even thickness front and rear on hand wheel side. Some TS don't shim on 4 corners, but use one continuous shim on quill side, and one continuous on hand wheel side.

To correct your tail stock will be trial and error. I'll bet you a dollar you will not shim the first time and be done. It takes some incremental steps, followed by checks. . . to see the result. The reason is basically like leverage. If you hold your arm straight out. . . raise your hand 6 inches, well it raised 6 inches. But now hold a 6' pipe straight out. Raise your hand 6 inches. . . Your hand raised 6 inches, but end of pipe raised 2 feet.

Same with TS with spindle, test bar, dead center, whatever. So if your down .025" on quill side, maybe .015" shims in between base and body bring it to center. But that's maybe. . .I don't know what the number is till you experiment.

You will most assuredly need to raise hand wheel side also. But it will be a smaller number. You will need a variety of shims so have a bunch of options on hand.

At a guess, I would start with .015" under quill side, and .010" under handwheel side. Run all your checks again. Then re-adjust. You'll be homing in more as you saw the first results, and how much reaction the shims gave.

The first time will be most time consuming. You need to pull TS off lathe. Split it and clean mating surfaces really well, de-burr, get all old paint out, etc. After that, your 2nd and 3rd step shimming will be faster. To split it, remove bed clamp and bolt, and totally remove the two, side to side adjusting screws. Might need to tap the two halves apart.

Recommend doing it on the floor. The TS is heavy, maybe 100lbs complete. I'm in the process myself on that 16" i'm going through. Here's the two halves split, and you can see it was shimmed on 4 corners.



Michiganbuck had a good point with checking taper, but I know you replaced quill with brand new recently, I'm assuming you haven't spun anything in taper yet.

Real good thread with knowledgeable guys chiming in. I think they are all correct, though different views in ways of doing things, adds perspective.

Might you advertise on craigslist and find a local guy with a surface plate? That would allow you to find the shim test to make the quill flat/horizontal..and then up to headstock height. Draw a map of that.
Find a way to evaluate the bed wear..and map that. Yes, your 16" face plate might be used for the TS measuring plate if near flat..

Shimming the tail to run is a poor method because you may need .015 at the front to make straight and another .010 for the entire to go up to headstock height. A varied shim stack in the tail would not be good. *Richards plastic and scrape would be much better (starting out with the best choice thickness to reduce scraping time}...(the glue adds some size , (Richard can tell us that amount)

Bed dip/wear might be tested roughly with a straight edge (perhaps borrowed).
Shoot for the best average to be near headstock center at where you might use the machine most often.

Zero to 10" out of the chick, in a collet, far out in a steady, long work between centers are some common most used places for different lathe shops.

A low priced surface plate (not the best but OK)
WoodRiver - Granite Surface Plate 12" x 18" x 3" A Grade

Here are some pictures of what I said.

Originally Posted by michiganbuck

Might you advertise on craigslist and find a local guy with a surface plate? That would allow you to find the shim test to make the quill flat/horizontal..and then up to headstock height. Draw a map of that.
Find a way to evaluate the bed wear..and map that. Yes, your 16" face plate might be used for the TS measuring plate if near flat..

Shimming the tail to run is a poor method because you may need .015 at the front to make straight and another .010 for the entire to go up to headstock height. A varied shim stack in the tail would not be good. *Richards plastic and scrape would be much better (starting out with the best choice thickness to reduce scraping time}...(the glue adds some size , (Richard can tell us that amount)

Bed dip/wear might be tested roughly with a straight edge (perhaps borrowed).
Shoot for the best average to be near headstock center at where you might use the machine most often.

Zero to 10" out of the chick, in a collet, far out in a steady, long work between centers are some common most used places for different lathe shops.

A low priced surface plate (not the best but OK)
WoodRiver - Granite Surface Plate 12" x 18" x 3" A Grade

Thanks for the reply there is some good stuff in it for me to ponder. I will try the shim route first because it's simple and I understand it. I thought for fun some of you guys might like to see what it is like to buy things and ship them to Hawaii. For heavy purchases I need to be sure I really want the item because shipping can really bend you over!

Originally Posted by Kevin T

...I will try the shim route first because it's simple and I understand it. ...

1) it's simple and it will get you close to better usability on the machine, fast.

2) you can refine the correction shims as you go.

3) once you have it dialed in the way you like, you now have a real understanding of what a proper re-build
of the tailstock has to look like.

4) you can undo the shim trick, trivally.

Once you start machining the bottom of the tailstock, there's no going back.

QT:[ I thought for fun some of you guys might like to see what it is like to buy things and ship them to Hawaii.]
That is why an in-store purchase store can be better than ordering heavy stuff.

Woodcraft of Honolulu

Good that the quill is/travels horizontal / in line with your headstock...as best you can.

My QT: Might you advertise on craigslist and find a local guy with a surface plate -> that he might allow you to use?

Might find a lathe buddy close by.

I spent a few years running a .010+ or so low-tail lathe and made the best of it (not mine)..nowadays I would shim it.

Originally Posted by michiganbuck

Woodcraft of Honolulu

HAHA! I know where that store is but I never went in. I was afraid I would want to much stuff in there. Thanks for pointing that out though. I guess I better check it out to see if they stock the goodies I like. Thanks!

QT kevin; [HAHA! I know where that store is but I never went in. I was afraid I would want to much stuff in there. Thanks for pointing that out though. I guess I better check it out to see if they stock the goodies I like. Thanks!]
$100 bucks for a surface plate that is handy for grinding but not so much for a lathe hand. Better borrow the use of one for a half-hour test.

Your test is with moving your carriage along the test bar to fined .008 to .010 done.

Just for the heck of this try another test: Set your Ts at the far end. place your indicator at the top front of the extended Quill (lightly tightened with two fingers)to zero, then move the tail forward to see indicator change. So a rough showing/test of the Quill error drop..not what to the headstock.

likely the bed may be least worn at the far end. Finding the drop there and then trying other places along the bed could give a rough idea of the bed condition.

Richard's test diameter to diameter tells the error to headstock so tell us what you found there.

Shimming inside the Ts at the parting line would be a poor fix because that would distort the bottom base when tightened so wearing convex or concave on the bed. Shimming with perhaps three shim sizes would be better but still a poor fix.
Richard's plastic and scrape is a better repair so full flat supported and no distortion.

Originally Posted by michiganbuck

Shimming inside the Ts at the parting line would be a poor fix ...

Ah, you never looked under the hood of any well-used SB lathes - they're all that way.

Option 1) use it as - is.
Option 2) shim it to be better.
Option 3) fix it nice as per RK's approach (pro tip: get a micrometer. ??)
Option 4) internet some more.

Yes, I have seen that (shimming) and done that on lathes and grinders.

(pro tip: get a micrometer. ??)
I think a caliper for .001 or .0005 is a huge asset for lathe work.
(I do have a full set of micrometers to 12" but use a caliper very often.)

A sheet of 12" x 12" x .015 plastic cost beans and does not take long to take stock..a surface grinder skim to allow .005 take stock with .010 os so glued can make it a quick job. even if one takes plastic stock with abrasive instead of a scraper to blue into the Ts upper's down side.

lose shims perhaps .008/.005 /.004 might be the quick fix.

He doesn't have a surface grinder. (?)

Paying for shipping he could borrow one of mine?

Although this is not a very good idea.