Tailstock Alignment and Shimming

Video of aligning the tailstock with a shop made test bar and how to shim the tailstock for height alignment. Enjoy!

South Bend Lathe Tailstock Alignment - YouTube

Great video - thanks for posting. I wouldn't mind seeing a video on how you made the test bar

Rick

Very informative video.I noticed that when running a large drill in the tailstock, the drill seems to be cutting on one side. After watching this I'm going to have to align the tailstock. I picked up a bar that I'm told was used to set a centerless grinding machine and it appears to be precision ground with two center drilled holes in the end. Would this be acceptable to use as a test bar? Thanks again for posting the video.

Chris

As long as the center drilled holes are accurate, the finish is smooth and concentric, and the bar not bent, you should be good. Also if it is percision ground along its entire length you technically would not have to flip the bar around like I had to.

Great job on video will come in handy when setting up my 10 k

Nice video, Halligan - it's good to go over the basics sometimes for the youngsters that don't know, and the oldsters that just forgot!

Fantastic video. I was always a little fuzzy on doing this. Now I think I can confidently get my tailstock in perfect alignment.

Thanks for posting this!

Cool video; its always nice to see how other people perform a similar op.

Glad people are finding it helpful

In answer to your question, no, it is not correct. You are introducing the potential error of a chuck/ collet system to hold your test bar. Test bars for lathes have the internal spindle taper on one end. Ideally you should use two test bars, one in the spindle taper and the other in the tail stock taper. You can then measure total parallelism and misalignment with a carraige mounted dial indicator.

CHRIS165 said:

Very informative video.I noticed that when running a large drill in the tailstock, the drill seems to be cutting on one side. After watching this I'm going to have to align the tailstock. I picked up a bar that I'm told was used to set a centerless grinding machine and it appears to be precision ground with two center drilled holes in the end. Would this be acceptable to use as a test bar? Thanks again for posting the video.

Chris

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Further to my reply. No tailstock realignment should be done without certain knowledge that the rest of the lathe is straight. If you feel there might be a tailstock problem, you had better make certain the bed is straight and the headstock is parallel to the bed. This is especially true with the small SB lathes, as very often the spindles are not parallel to the bed. The only way to do this is with precision ground, taper mounted test bars.
Steve

steve-l said:

Further to my reply. No tailstock realignment should be done without certain knowledge that the rest of the lathe is straight. If you feel there might be a tailstock problem, you had better make certain the bed is straight and the headstock is parallel to the bed. This is especially true with the small SB lathes, as very often the spindles are not parallel to the bed. The only way to do this is with precision ground, taper mounted test bars.
Steve

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I am often suspicious of a statement proclaiming that there is only one way to solve a problem .
A test bar would be nice to have , but not essential .
Maybe look into " Rollie's dad's method " , that ought to really drive you nuts .
Using a worn out chuck and a crooked piece of bar stock , headstock can be aligned with ways .
This video is not about bringing the lathe into perfect alignment , but about tailstock set over and re- alignment .
A good way to get into the ball park , good enough for drilling , would probably be followed with test cut and adjustments if turning between centers .

Halligan , nice video , a little hard to watch at the beginning while looking at the bench , but helpful ; especially the shimming part ; easier on the drills .
Here's another way to do essentially the same thing . From Frank Ford's excellent site : HomeShopTech

steve-l said:

In answer to your question, no, it is not correct. You are introducing the potential error of a chuck/ collet system to hold your test bar. Test bars for lathes have the internal spindle taper on one end. Ideally you should use two test bars, one in the spindle taper and the other in the tail stock taper. You can then measure total parallelism and misalignment with a carraige mounted dial indicator.

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How are you introducing chuck error if you are holding the test bar between centers?

The test bar I used was faced and center drilled using a 4 jaw chuck (after prelim tailstock alignment with a razorblade and the two centers) to dial it in then held between centers to machine the collar on the end. I agree you have to be sure the bed is straight but that should be part of your set up before you start cutting anything. It may not be aerospace accurate but I'll be damned if its not within tolerance of normal work especially if you were to use a more sensitive DTI. The cheapest taper mount precision test bar I have seen is about 125. Way too much in my opinion for chasing a thousandth to within a nats ass on a 62 year old machine.

P.S. I dont mean to sound argumentative and I'm sure you know what your doing and thats most likely a lot more than me. I also know that many people have different ways of doing things that get the same results. I confess I am NOT a machinist and never claimed to be. But I will argue my point and defend this method especially since the machinists I know that taught me this use this method all the time and achieve results I could never dream of coming close to.

PeterJ- Thanks for the comments. I know the bench stuff was kinda crappy but my canera is old and the focal length is kinda crappy. I've looked at the rollie's dad method. That threw me for a loop. I'm sure it works great but i could never wrap my head around being able to use a bent bar and/or worn chuck. Thats also the first time ive seen the other technique. Ive used razor blades in the past pinched between centers for a down and dirty quick alignment.

Like you said, Halligan - good enough for almost all work! I just went and made myself a test bar like yours. The way I figured out how to dial in my tailstock originally though, was to turn a piece of aluminum, clamp a test indicator with an Indicol to the turned piece, then swing the inside of the tailstock taper.

Two things, what happens when there is bed has wear? does it matter? Ok three things, I have another way use a lathe dog clamped on a dead center at the head stock backward, use a dial indacator mounted on the dog arm facing the tail stock ( I drilled a mount hole in a home made dog to hold the dial) this will allow you to turn the head stock by hand and follow the tail stock dead center around, seems to work pertty good. think I saw Tulbocain do this on you tube. Hope this makes sense. Your idea is a good one though, great video.

There are many ways that have been used to align a tailstock. This is only one, but as I stated it does not address total alignment. This method only addresses the spindle center to tailstock center. This is fine if all you do with the lathe is dog driven, center to center turning. I mean nobody would be doing an alignment if there was not a suspected fault. Before any corrective action is performed, you need to know what the problem is. Think about it, wear is very rarely, if ever, uniform. Taper mounted test bars are made for just this purpose.

steve-l said:

There are many ways that have been used to align a tailstock. This is only one, but as I stated it does not address total alignment. This method only addresses the spindle center to tailstock center. This is fine if all you do with the lathe is dog driven, center to center turning. I mean nobody would be doing an alignment if there was not a suspected fault. Before any corrective action is performed, you need to know what the problem is. Think about it, wear is very rarely, if ever, uniform. Taper mounted test bars are made for just this purpose.

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Correct. This is for tailstock alignment as the title states and also to measure tailstock offset for taper turning and to get it back to center when done. Something everyone should do when they first get a lathe and if they ever split the tailstock casting apart like I did when I cleaned and painted it. Misalignment due to bed twist is measured and remidied by a machinist level and using the "two collar test" found in HTRAL and I also belive iwannanew10k has a video of it. On any lathe you are going to be fighting wear. If your bed wear is significantly measurable you have a whole other set of problems. You are absolutely correct that a taper mount test bar is the most accurate way to gauge bed wear and tailstock alignment using two test bars. Thats over $250 I personally would rather spend somewhere else other then the $10-$15 to make a pretty accurate test bar. To each his own.


klrray: I have tried the method you described using a coax indicator mounted in a collet. Only Issue I found was that you run into an issue with hitting the quill key slot on the bottom and also the quill does have a little bit of movement in its socket that was throwing me off.

i just tried this method on my 9a. found my tailstock was .004 low. added .005 shim and it came back to .000. this is a fast and easy way to do this for me and i like it. thanks for taking the time to explain it. cheers jim

Halligan said:

Misalignment due to bed twist is measured and remidied by a machinist level and using the "two collar test" found in HTRAL and I also belive iwannanew10k has a video of it.

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LOL!! i`m glad you recognized what it was! you shoud do a video of it - i`m limited to less than a minute and i don`t think everyone realized what i was showing was the basic two-collar test.
maybe the use of the indicator threw people off??

i`m with you on the use of precision test bars(and levels ) on used machines - i just don`t see the value unless someone actually plans to do a precision re-build.

we make do with what we have at hand. excellent video.

iwananew10K said:

LOL!! i`m glad you recognized what it was! you shoud do a video of it - i`m limited to less than a minute and i don`t think everyone realized what i was showing was the basic two-collar test.
maybe the use of the indicator threw people off??

i`m with you on the use of precision test bars(and levels ) on used machines - i just don`t see the value unless someone actually plans to do a precision re-build.

we make do with what we have at hand. excellent video.

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Yeah that got out of hand real quick. I actually have a level that was bought from CDCO. Not too expensive. Made in China but hell for the amount I've used it it's worked out well. Only issue is my lathe is so long that the apron will actually twist the bed some amount. So I figured out where most of my work will be done, moved the carriage to that spot and levelled from there. I haven't done the two collar test yet. Would be interesting to see how that pans out. Maybe I'll pick up some larger round stock and make a bar up like yours and snap a quick video.

I'm glad people are having success with this method.