# Taig Lathe Runout



## benster (Feb 18, 2016)

I'm having trouble with runout on my Taig lathe. Starting out I'll center work in a 4 jaw chuck, usually to within .0005. I'll also use the tailstock. Workpieces around 2-4" long, about .5"-1" diameter. The problem is after roughing passes, and finishing passes of .001 I'll still end up with about a difference of .003-.005 in the end diameters.  I've tried making my last pass or two a spring cut and I still end up with runout. Do I need to be using a follow rest? Should I just not expect more accuracy on a lathe this small? Would turning between centers help?


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## canadianhorsepower (Feb 18, 2016)

benster said:


> ? Would turning between centers help?



that`s your answer
rule of 3 not more then 3 time the diameter sticking out
without support


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## benster (Feb 18, 2016)

I do use the tailstock though, just not a faceplate.


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## ICEpeter (Feb 18, 2016)

Benster,
Have you checked to make sure your tailstock is correctly lined up and not off center?

Peter J.


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## t.l.a.r. eng (Feb 18, 2016)

How old is your Taig? Perhaps the bed is worn hourglass shapped.

An easy check for that is seeing if the carriage is looser towards the chuck and tighter towards the end of the bed.

An out of line tail stock will skew the work off center with a chuck an amazing amount, good reason to turn betwen centers, another check.

Check the four jaws to see if the jaws gripping surface is 90 degrees to the face and not worn.

Just my experience with a Taig with over 1600 hours on it. In good shape and set correctly it should hold to less than .001 deviance along the travel.


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## benster (Feb 18, 2016)

Its only about a year old and I've lapped it a few times in that period. I'll try aligning my tailstock more accurately and see where that gets me.


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## barnesrickw (Feb 18, 2016)

Mine has seen some rough use as it was my first lathe, and suffered through my learning curve, but the runout is still less than .001.


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## Swifty (Feb 18, 2016)

Benster, you have called the topic heading runout, when you actually have a problem with taper on your work. Runout is something different altogether, I'm sure that your problem is with the tailstock alignment. One way to adjust the tailstock is to use a dial indicator and run it along your turned workpiece, it should read zero all the way along, then let's say that the tailstock end of the work is .004" bigger than the other end, adjust the tailstock so that the indicator reading is zero at the headstock end and +.002" at the tailstock end (half the difference). This will mean that you will be turning more off the larger end and hopefully be parallel all the way along.

Paul.


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## goldstar31 (Feb 19, 2016)

A 'Garden Gate' engineering rather than a precision suggestion is to put in a couple of centres and nip a 6" rule between them.

Let me know

Norman


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## abby (Feb 19, 2016)

Workpiece 3-4 inches long, 1/2 to 1 inch diameter , centered in a 4 jaw !
No way does this need a tailstock centre for turning such a piece , look elsewhere , try adjusting the carriage for a start.


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## benster (Feb 19, 2016)

I did try adjusting my tailstock and it was a little out "left to right" I adjusted it to about .0005. However, it's off by .001-.002 vertically, is there some way to shim the Taig tailstock? The way its built I can't think of a way. Also, I've tried adjusting the carriage gibs but they're just at the point where any tighter and it won't slide.


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## goldstar31 (Feb 19, 2016)

Please define what you mean by 'lapping several times'.
Again, let us know  how you are getting such claimed 'inaccuracy- or accuracy'.
You are using arguably one of the cheapest and smallest of lathes yet by deduction , you are able to measure to half a thous which means that  you possess or  have access to  inspection equipment  capable of measuring in 'tenths'

I may be wrong but that is how it comes over to me.


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## benster (Feb 19, 2016)

The first time I got the inaccuracy I thought it was poorly adjusted gibs, so I took the lathe apart and used lapping compound to lap the gibs/carriage to the ways. When I adjusted the tailstock I used a test indicator with half thou resolution. My diameter measurements are with Mitutoyo Absolute calipers or micrometer. I center work in the 4 jaw with a dial indicator, then with the test indicator.

Just because I have a cheap/small lathe doesn't mean I don't have good auxiliary equipment or lack the knowledge to use them.


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## canadianhorsepower (Feb 19, 2016)

benster said:


> Don't bother that kind of comment from him,:hDe:
> I have a Taig and 2 others and even if it's small it's dead on accurate.
> as for the up and down offset  not often:wall::wall: some people
> did mill the under side of the tail stock and added a small brass plate
> ...


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## goldstar31 (Feb 19, 2016)

Apologies but I was merely trying to find out the problem and was going to attempt to answer it.
 I'm playing with a little Unimat clone- a MJ189 . Amazing what can be done with a scraper and a trace of Engineers blue. 

Norman


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## bazmak (Feb 19, 2016)

The tailstock height is not the critical dim.The front to back alignment is the important dim.It affects taper turning greatly but is the easiest one to adjust
If the heights are within 2 thou then I would suggest it is near enough,
the front to back should be adjusted as accurately as possible.
If possible,grip the job in a collet and use the tailstock centre.This usually gets within a thou for me


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## Wizard69 (Feb 22, 2016)

benster said:


> The first time I got the inaccuracy I thought it was poorly adjusted gibs, so I took the lathe apart and used lapping compound to lap the gibs/carriage to the ways. When I adjusted the tailstock I used a test indicator with half thou resolution. My diameter measurements are with Mitutoyo Absolute calipers or micrometer. I center work in the 4 jaw with a dial indicator, then with the test indicator.
> 
> Just because I have a cheap/small lathe doesn't mean I don't have good auxiliary equipment or lack the knowledge to use them.




I generally cringe when I see mention of ways, Gibbs and lapping compound.  It is generally a bad idea to use lapping compound to correct fit up problems.  I know this can lead to endless arguments but if you machine has fit up problems you really want to consider scrapping in the components.   Lapping simply isn't a controlled way to correct fit up issues.


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## bazmak (Feb 22, 2016)

If the tailstock is high then simply tape some wet/dry paper to the bed
A few minutes stroking the tailstock over the WD should remove any high spots
and lower 2 thou easily


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## dalem9 (Feb 22, 2016)

No one has mention if the bed may have a twist in it . Not likely but still possible on such a short bed ! Keep looking you will find the problem .


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## canadianhorsepower (Feb 22, 2016)

dalem9 said:


> No one has mention if the bed may have a twist in it .  .



the bed is made out of ciment


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## bazmak (Feb 22, 2016)

I would say this.For a small lathe there is a limit to how accurate you can get it
Forget bed twist and head misalignment etc.If you already within a couple of thou then just try improvement with what you can.Be happy with what you can get.A couple of thou is ok don't think of getting within tenths.If its a small lathe it is possibly just sitting on a bench not bolted down to a solid/flat surface
Make a test piece if possible gripping in a collet and skimming down between centres,max length poss for your lathe.I made one from 1"dia bar x 12" lg
and took light skims with a sharp tool,adjusting the tailstock and bedding it in
If I remember I got the tailstock to +2thou and the test piece to 1 thou taper
Good enough for me.If you want greater accuracy then polish down with emery OR buy a new lathe.Did a thread on it you mind find useful under Bazmak diary of a benchlathe Regards barry


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## barnesrickw (Feb 22, 2016)

I guess it could have a bend, but I think there would be other larger problems that caused this.


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## gerritv (Feb 22, 2016)

benster said:


> I did try adjusting my tailstock and it was a little out "left to right" I adjusted it to about .0005. However, it's off by .001-.002 vertically, is there some way to shim the Taig tailstock? The way its built I can't think of a way. Also, I've tried adjusting the carriage gibs but they're just at the point where any tighter and it won't slide.



Been there, done that, on my Taig the solution was to shim the headstock up.

Gerrit


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## goldstar31 (Feb 23, 2016)

I am afraid that despite the well meaning advice, the vertical adjustment of the tailstock or spindle height is 'a Red Herring' or a waste of time to those whose English may be a second language. The concept written by the experts in machine tool design and restoration suggest that come out in favour of what 'Taig' did- and every other machine tool manufacturer In other words, leave well alone and concentrate on what is either worn or badly adjusted.
Benster's remark about 'being half a thous out in lateral adjustment' should be addressed. It reflects a full thous in diameter although a half thous in radius. It may be more or less or it may be less but that is the 'measuured' figure which he alone can provide.
In a small workpiece, this is a substantial matter and needs addressing.

What also needs attention is this 'lapping' thing. I have tackled many machine tool problems and 'lapping' is an expedient to be avoided. I doubt that few here can achieve 25 spots or points of contact by lapping but it can by scraping and bluing- against a known 'reference'.

I'm using 'machine tool' phraseology as in Connolly who still is a standard of good practice. Using a stone to break the crests of the spots is acceptable and expected. 

What must be remembered is that a Taig( like ant other lathe) has very little points of contacts on the bearing surfaces and as such it becomes imperative to try get 100% bearing surfaces or a minimum of 25 spots per square inch. If one doesn't get to this state , saddles and shims and whatever will 'rock' A small amount of rock may be allowed in a bigger lathe but certainly not in something so small. 

So I can only apologise yet again for what appears to be a 'lecture' but I have actually restored a number of lathes for myself and for friends.
As Barry rightly summarises, you may have to accept lower standards of accuracy than envisaged or if you are unwilling to follow what the experts( not me) have decreed, one buys a better lathe.

Not my words, I am simply trying to put into a very small précis, what runs into hundreds of pages which- I have to remark- have been cited quite recently by other contributors.

Therefore, I wish you greater success in future.


Norman Atkinson


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## gerritv (Feb 23, 2016)

> I am afraid that despite the well meaning advice, the vertical adjustment of the tailstock or spindle height is 'a Red Herring' or a waste of time to those whose English may be a second language. The concept written by the experts in machine tool design and restoration suggest that come out in favour of what 'Taig' did- and every other machine tool manufacturer In other words, leave well alone and concentrate on what is either worn or badly adjusted.


Except when you try using a very small centre drill and your tailstock/headstock is misaligned. Snap goes the tip. Sherline made their tailstock chuck adapter adjustable for a reason.

As an expert watchmaker on another forum indicated, for machining Taig, Sherline and the like you need to think differently from 'the big stuff', ala Sieg and up.


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## Wizard69 (Feb 23, 2016)

goldstar31 said:


> I am afraid that despite the well meaning advice, the vertical adjustment of the tailstock or spindle height is 'a Red Herring' or a waste of time to those whose English may be a second language. The concept written by the experts in machine tool design and restoration suggest that come out in favour of what 'Taig' did- and every other machine tool manufacturer In other words, leave well alone and concentrate on what is either worn or badly adjusted.
> Benster's remark about 'being half a thous out in lateral adjustment' should be addressed. It reflects a full thous in diameter although a half thous in radius. It may be more or less or it may be less but that is the 'measuured' figure which he alone can provide.
> In a small workpiece, this is a substantial matter and needs addressing.
> 
> ...



The short form here is that lapping together poor fitting parts of a machine tool is simply bad practice.  I know a lot of people don't want to hear this but I had the concept drilled into me in my teens working with an extremely talented machine tool rebuilder.


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## benster (Feb 23, 2016)

The issue started when I tried to build a spindle for a dividing head and had a .005 difference end to end. Until I can purchase a new lathe I'm going to just design my devices to account for wear/runout etc. It adds extra complexity but will allow me to adjust for the issues I've encountered.


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## goldstar31 (Feb 23, 2016)

benster said:


> The issue started when I tried to build a spindle for a dividing head and had a .005 difference end to end. Until I can purchase a new lathe I'm going to just design my devices to account for wear/runout etc. It adds extra complexity but will allow me to adjust for the issues I've encountered.[/QUOTE
> 
> Probably the taper for your dividing head is solved fairly easily.
> 
> ...


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## benster (Feb 23, 2016)

Do you use a standard scraper for this or is there a special scraper for cylindrical surfaces?


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## goldstar31 (Feb 23, 2016)

Apologies for delays but being old, I get phone calls from my grown up kids. One of which has invited me for Easter and the other is going to pick  my new/old lathe up. 
So your problem? Yes, you need or would benefit from a curved scraper rather than a flat one. That doesn't mean that you need to go out and buy one. At a ;pinch, you could use a boring bar end or even a penknife on soft plastic or even softer metals. 

My best scraper is the hollow arm from a pair of scrap lawn edging shears with a b it of carbide lathe tool stuck or screwed in. I have no doubt that once you have the idea roughly, you will find an cost free alternative. Maybe you have access to the right size drill or reamer and you can forget the scraper. 

PS, I've given you a 'like' because you are now thinking. Good!

Cheers

Norman


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## benster (Mar 8, 2016)

So with the attached setup I have 1.021" at the dead center and 1.023" at the chuck. I had dialed in the dead center to less than a thou of center horizontally. I used both calipers and micrometers to measure. The work piece is only sticking out about 1.5". I guess I have to live with it.


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## bazmak (Mar 8, 2016)

I would say that the obvios problem is the length of the dead centre


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## Swifty (Mar 9, 2016)

Benster, you have to go back a step, with the diameter of the piece and that overhang you shouldn't need to support the end with a centre. Actually, with that much overhang of the centre the work piece will be forcing the centre over. Now, without the tail stock and centre in place, take a light cut over the piece in the chuck. If it is still tapered, then the problem lies with the alignment of the headstock, which will have to be corrected. If it cuts nice and parallel as is, but not with the centre in, then the problem is with the centre / tailstock, which will have to be corrected.

Paul.


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## benster (Mar 9, 2016)

This is the article regarding the dead center design.

http://www.cartertools.com/dead center.html

Following Dean's example from.

http://www.deansphotographica.com/machining/projects/deadcenter/deadcenter.html

I don't remember what dimensions mine came out to exactly but it does look about an inch too long. Surprisingly enough, after I got the piece closer to final dimensions of .850" diameter, the taper was less than a thou, or within the accuracy of my calipers - with the tailstock in place.

Like I stated previously the taper is such an issue because I'm trying to make shafts and bearings. This piece is going to be the front spindle bearing for my old craftsman 109. Normally a couple thou would be acceptable, just not when I'm trying to create bearing surfaces like this.


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## fencer (Mar 12, 2016)

Benster,is the lathe fastened down,if so it is possible that the bed has a slight twist and by adjusting the hold down bolts to remove this may be the answer.I have done this to get accuracy on my Myford,just a thought.
Frank


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## t.l.a.r. eng (Mar 12, 2016)

benster said:


> So with the attached setup I have 1.021" at the dead center and 1.023" at the chuck.



For the setup as shown, you realy shouldn't need support with a Taig. To loose .002 in such a short distance, something is wrong.

The Taig headstock bearings are supported by a two piece design that clamps the bearings and the bed at the same time. Perhaps taking the headstock apart and clean out the chips and or burrs where the bearings rest. 

Perhaps the bed is worn with an hourglass shape where the carriage normally runs.

Is the tool height off causing too much pressure on the workpiece? I find with mine if the tool height is off or the tool is dull it puts too much pressure on the work and then causes tapers on long runs. 

I'm sure you may already know about these things, just throwing out what I have experienced with my Taig


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## goldstar31 (Mar 13, 2016)

What happened to Georg Schlesinger?  Is he no longer the Flavor of the Month? 

N orman


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## barnesrickw (Mar 13, 2016)

Carter Tools mentioned above is the best Taig resource out there.  Nick Carter is very helpful, answers his emails quickly and has a great knowledge of the lathe.mm


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