Tail Stock Alignment.

**cba_melbourne** · 1st February 2015, 09:21 AM

Originally Posted by Michael G

Not quite - you can do accurate work that is concentric in a 3 jaw chuck provided it is machined all over and all done in one set up - that is, the work is not repositioned in the chuck. If you are trying to reposition a part or match up to previous work then yes, a 4 jaw or working on centres is the more preferable method.
In this particular case provided the diameter is measured across 2 freshly machined surfaces it should give a valid number to work with.

Michael

Well... if its a worn out old chuck with sloppy and convex jaws that that let the workpiece wobble with the slightest side force... good luck.

It depends to what degree of accuracy the op wants to align his tailstock. There are many ways to skin this cat. From what I see so far, I believe the OP could go away with the simplest method: put in a dead center (in good condition, with sharp tip and no burrs on the taper) in each hearstock spindle and tailstock, and lightly clamp a razor blade or a short steel ruler in between the tips. When the razor blade looks visually at right angles to the bedways horizontally and vertically, the tailstock is aligned to better than 0.1mm. Good enough for simple and rough tasks.

If a more accurate alignment is necessary, maybe to accurately drill very small diameter holes, I found that a DTI mounted dirctly and in a straight line from spindle chuck and indicating the inside of the tailstock taper will allow Tailstock alignment to 0.01mm accuracy. This is good enough for advanced precision TS drilling tasks.

Now if the OP also needs to turn very accurate parts between centers, it is additionally necessary to either turn a shaft BETWEEN CENTERS and measure it at both ends with a micrometer, or put an accurate shaft between centers and measure it (a previously made shaft made between centers and known to be reasonably round and parallel and with undamaged center pips). Needless to say that once you need a TS aligned that accurately, it is a prequisition that first is is verified the bed is properly untwisted (for example with a test cut on a spool that is NOT supported by the TS).

If a perfect check and alignment in all axes is necessary in the shortest possible time, then a proper test bar fitting into the TS taper is used. Not everybody can afford to buy such a test bar for use only once in a year though, and that is why people seek out alternative methods using what is at hand. And because such test bars are also very fragile, people that own one are usually reluctant to loan it out.

**wm460** · 1st February 2015, 05:00 PM

I found two test bars on the internet

Aust $120.00 free post, 0.01mm max run-out

UK $89.44 including postage,parallel to within 0.0002".

**pipeclay** · 1st February 2015, 05:41 PM

Have you turned a bar between centres yet,or do you just want to spend money,if the latter I will send you a bar for $60 including post.

**Michael G** · 1st February 2015, 06:19 PM

Originally Posted by cba_melbourne

Well... if its a worn out old chuck with sloppy and convex jaws that that let the workpiece wobble with the slightest side force... good luck.

And exactly the same thing would apply to a 4 jaw chuck. Please compare apples with apples. If you are going to compare a worn 3 jaw to a pristine 4 jaw then of course it will be better.

Michael

**wm460** · 1st February 2015, 09:33 PM

Using a Wixey digital angle gauge I took readings at each end of both side of the bed, parallel they all read 0.0 and cross ways they all read 0.1.

Turning a 19 mm dia bar, measuered at both end. about 200 mm long I got 18.90 mm at tail stock end and 18.60 at head stock.

**Stustoys** · 1st February 2015, 09:37 PM

Originally Posted by wm460

Turning a 19 mm dia bar, measuered at both end. about 200 mm long I got 18.90 mm at tail stock end and 18.60 at head stock.

With or without the tailstock supporting the bar?

19mm is pretty small dia for this sort of thing.

**wm460** · 1st February 2015, 09:48 PM

Originally Posted by Stustoys

With or without the tailstock supporting the bar?

19mm is pretty small dia for this sort of thing.

This was done between centers.

**cba_melbourne** · 1st February 2015, 10:04 PM

Originally Posted by Michael G

And exactly the same thing would apply to a 4 jaw chuck. Please compare apples with apples. If you are going to compare a worn 3 jaw to a pristine 4 jaw then of course it will be better.

Michael

Michael, no, I was comparing it to a bar held between centers! Holding it in a chuck - any chuck - is simply not a good idea.

**Machtool** · 1st February 2015, 11:01 PM

So in summary. You never ever adjust a tailstock, because its headstock, bearings, 3 jaw chucks, vodoo, make it cut out of parralel.
You'd never ever adjust a tailstock, even thou every lathe ever made has that adjustement?

**.RC.** · 1st February 2015, 11:19 PM

Originally Posted by wm460

I found that my tail stock was know longer in alignment with the head stock.

I put a 200 X 25.05 mm piece of aluminium, turned a sliver off of it.

24.90 mm tail stock end
24.85 mm head stock end

To fix this do I loosen the tail stock and move it 0.05 Towards the front of my lathe?

I have a Steelmaster 9 X 20 lathe.

There is a lot of buggerising around to get it right, one think to keep in mind it on some lathes and I owned one like this, the tailstock would move sideways considerably between locked and unlocked.. it is just something you have to put up with if it does it.. I have never had much luck keeping tailstocks in near perfect alignment all the time.... So I say near enough is good enough these days...

Near enough for me is usually about 0.02mm or so parallel turning... over 300mm or a bit less... If I need better I will chase my tail for a couple of hours getting it right, but most of the time, near enough is good enough...

**cba_melbourne** · 1st February 2015, 11:23 PM

Originally Posted by Machtool

So in summary. You never ever adjust a tailstock, because its headstock, bearings, 3 jaw chucks, vodoo, make it cut out of parralel.
You'd never ever adjust a tailstock, even thou every lathe ever made has that adjustement?

Who said that? Why are you so arrogant with your comments? If you have something to contribute, do so in a civilized manner. Being good at scraping and packing up large lathes does not make you a god.

**Michael G** · 2nd February 2015, 07:13 AM

Originally Posted by cba_melbourne

Being good at scraping and packing up large lathes does not make you a god.

Chris, I've seen the work that Phil does and his workshop, as have a number of others here. He has demonstrated to us both there and on this forum that he knows what he is talking about. If you would like to post some pictures of your machines, tell us what you have done to rebuild them in a better form and show us some of your projects then your comments may be better appreciated because we can then see some of the learned experience behind what you say.
Entirely your choice of course.

Michael

**PDW** · 2nd February 2015, 07:13 AM

Originally Posted by .RC.

Near enough for me is usually about 0.02mm or so parallel turning... over 300mm or a bit less... If I need better I will chase my tail for a couple of hours getting it right, but most of the time, near enough is good enough...

Yeah, same. Only time I bother chasing better parallelism is if I'm doing bearing fits on a shaft and even then, a bit of Loctite makes the problem go away. In addition, if I need this level of accuracy I turn between centres even though I have a *very* good and accurate collet chuck for my lathe.

Must admit that this has been thrashed to death so many times here, on PM & YouTube (plus no doubt many other places on the Web) that it's utterly boring. Anyone who hasn't aligned their TS would be a LOT better off actually doing some reading on their own behalf before starting yet another thread on such well ploughed ground. It isn't exactly rocket science.......

PDW

**RayG** · 2nd February 2015, 12:20 PM

Originally Posted by wm460

Using a Wixey digital angle gauge I took readings at each end of both side of the bed, parallel they all read 0.0 and cross ways they all read 0.1.

Turning a 19 mm dia bar, measuered at both end. about 200 mm long I got 18.90 mm at tail stock end and 18.60 at head stock.

A couple of points to help...

1. Forget the Wixey type devices, they aren't going to be sensitive enough for levelling. They are usually +- 0.1 degree, which is 2mm per meter, machinist levels are around 0.05 mm/meter 40x times more sensitive.

2. You don't need a test bar to adjust the tailstock, if you already have one, no problem, use it. but there are lots of other methods that work just fine.

3. Schlesinger's limits for acceptance on parallelism for turning between centers is 0.02mm ( any distance ) and 0.03mm per 300mm otherwise. Don't chase shadows.

Ray

Thread: Tail Stock Alignment.

Thread Tools

Search Thread

Similar Threads

tail stock alignment the easiest way ?

tail stock problems???

Tail stock trouble.

Separating tail stock

Head Stock & Tail Stock extention plates

Tags for this Thread

Posting Permissions