# 3jaw chuck alignment problem



## Anatol (Mar 8, 2019)

I have an alignment problem with my 1980s Frejoth 12x37 lathe (very like a Grizzly 4003, and various ENCO etc) and 6” D1-4 3jaw chucks. I know 3 jaw chucks are not that accurate but I think it should be better than what I’m seeing. D1-4 backing plate is running acceptably true - within 1 thou radial and axial. The back edge of chuck (where I can get a gauge) is also running within 2 thou of true. 


A rod set in the jaws describes a cone. Close to the jaws, the rod is 10-15 thou out, but 4” down the rod the error increases to 30 thou or so. Tracing back along the rod into the chuck, this would suggest the minimum error on the rod - the point of the cone - would be back inside the chuck - if you could measure it. 


Thinking is was a jaw issue, I got a new-to-me 6” 3 jaw d1-4 chuck, chinese, relatively new and in good condition. It shows almost the same error! I then tried slipping a shim inbetween backing plate and chuck. Oddly this did not change the error much.


I’m quite confused and would be grateful for any insight or advice.


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## Wizard69 (Mar 8, 2019)

The idea that the “new” chuck performs the same as the old suggest to me a spindle nose problem.  

Your runout values could be good or terrible blue depending upon where the measurements where taken. You really want a high precision dial indicator because measuring to a thousands isn’t good enough.  You would have to do a bit of trig to find out if the axial runout is enough to cause your issues.  

Given that I’d mark your spindle nose so that the marks can be seen with the chucks mounted.   After which I’d mount and test both chucks to see if the high point is consistent with both chucks.  

Actually at first it might be a good idea to check for burrs or dings on the spindle nose.   Also take the cam lock mechanisms apart and clean.  It takes very little at the chuck nose to cause significantly can’t chuck issues.


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## DJP (Mar 8, 2019)

Try test rods of different diameters to confirm that it's not a worn scroll problem. I have scrapped a few 3 jaw chucks once the scroll causes runout. There is a solution to bore out the jaws when clamped on a bearing ring at the back of the chuck but this only fixes the problem for that diameter. 

A new chuck is my preferred solution.


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## Lloyd-ss (Mar 9, 2019)

New guy here, but I might as well jump in and embarrass myself right away. Because I don't yet know you guys, my apologies if my suggestions are things you've already done or thought about or just too basic. But alignment problems are usually harder to diagnose than you think they should be. I had the same problem with my Grizzly 5" chuck and was able to improve it noticeably.

First off, I am assuming you haven't had a bad crash on the machine recently, I know that only happens to other people. Also, I guess you've removed and cleaned the jaws in the chuck.

The condition you are describing, 15 thou in 4" is pretty extreme. First, remove the chuck and check the squareness of the spindle nose as follows. 

1, Lightly stone the mounting face of the spindle nose to identify and remove any burrs. No high spots should show up.
2, With a mag base on the cross slide, and dial test indicator tip on the face of the spindle nose, rotate the spindle and check the face for runout. Anything other than zero (or darn near zero) would be surprising, and bad. A machine problem, not the chuck. 
3. With the indicator still mounted to the cross slide, adjust  the location of the indicator tip so that you can traverse the  the spindle mounting face from front to back, covering as much of the spindle face diameter as possible. Basically tracing a chord across the spindle face. Again, anything other than zero would be surprising and again mean a machine problem. Without moving  the carriage or indicator, rotate the spindle at 60 degree intervals and traverse the cross slide front to back at each location. All readings should be near zero. Anything else is a machine problem.

If the spindle nose checks out ok, and I hope it does, next is the chuck.
4. Lightly stone the mounting face of the chuck to identify and remove any burrs. Load your chuck into the lathe. Load a known straight rod at least 1" in dia x 8" long into the chuck, with 5" sticking out. Set the mag base on the cross slide and the dial indicator tip at 12 o'clock on the rod at one inch away from the chuck jaws. Rotate the spindle to find the high point of the rod. Note the TIR and mark the 12 o'clock high point of the rod with a sharpie.  Also mark the chuck, the nearest jaw, and a visible part of the spindle nose, all at 12 o'clock. With the indicator still at the 12 o'clock high point on the rod, move the carriage along the length of the rod. You said that showed a 10-15 thou rise on the indicator, correct? Rotate the spindle to verify that the high point at the end of the rod is aligned with the high point near the chuck. Mark the rod at 12 o'clock. 

You should now have a series of lines marking the high point at 12 o'clock on the rod, chuck, jaws, and spindle. Also, at this time, number the individual chuck jaws and chuck slots as 1,2, and 3.

5. With the rod and spindle still in the 12 o'clock orientation, move the indicator and its base so that the indicator tip contacts the front of the rod, near the chuck, at 9 o'clock. Traverse the carriage along the length of the rod and hope to see zero movement. If you see more than zero, adjust the indicator tip so that it follows along the centerline of the rod, not too high, and not too low. If you are traversing the length along the CL of the rod, the curvature of the rod would only show a 2 tenths movement of the indicator. But if you are 50 thou above centerline, you'd see almost 2 thou movement. Kind of a false positive. The point of this part is to find out which way things are "bent", and get some baseline marks in place. So, everything should be marked, and "bent" upward toward 12 o'clock.

Up to this point, there should have been no surprises and everything should have gone as described. I hope, LOL.

6. OK, now to finding the real problem.
With everything back at 12 o'clock, re-set the indicator to touch the top of the rod at it's 12 o'clock high point near the chuck face. Rotate the spindle and set the indicator to read zero at 3 and 9 o'clock and high and low at 12 and 6.

7. Check the rod. Leaving the spindle at 12, barely unchuck the rod and rotate it 180 degrees to 6 oclock. Indicate your rod again at 12 oclock at both ends. The indicator readings should not have changed. If they changed, either the rod is bent or the chuck repeatability is really bad. But lets assume the readings stayed the same.

8. Leaving the rod chucked in the chuck, remove the chuck and reinstall it rotated 120 degrees. Now, with the indicator again at 12 oclock and the chuck and rod at 12, and the Spindle off by 120 degrees, recheck the dial indicator readings. If the indicator readings are the same as before, that means the runout is following the chuck and not the spindle. Move the chuck to the next set of holes to verify that the runout stays with the chuck.

So what happened? Did the runout follow the chuck or the spindle?
Move everything, including the chuck and spindle, back to the 12 o'clock position.

9. Now check the chuck jaws.  With everything back at 12, verify that the indicator readings are the same as they were in step 6. 
10. Remove the bar and the chuck jaws after making sure that everything is still marked. Reinstall the jaws indexed to the next set of slots, and rechuck the bar. Align all the marks at 12 oclock except that the chuck jaws will now be off 120 degrees.  Set the indicator back up and check the top of the rod and see if the readings are the same as in step 6. My guess is that they will Not be the same. You'll probably  find that the runout has kind of followed the jaws, but not exactly. 
11. Now, rotate the spindle to get the high point of the bar again at 12 oclock. So, is the high point still in relation to the original jaw? If it followed the jaw, you are lucky, because it might just be a jaw problem. 

12. You will probably find that the readings are best with the jaws installed in one particular position, and that the runout is tied to the location of the jaws. As previously suggested, try some different diameter bars to see if its a scroll problem, too. But if its mostly the jaws you can clamp a ring deep in the chuck and bore them out just enough to clean up. Make sure to permanently mark the number one jaw position. After boring the jaws, you'll have to hand finish the section of each jaw that clamped onto the ring.

I had to go thru this procedure with my 5" 3 jaw and I got the runout an repeatability from about 9 thou  down to 2 thou. I would have liked better, but that is why we have 4 jaw chucks, right?

My apologies for the long winded post, but i hope it might help somebody.
Lloyd-ss


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## Anatol (Mar 10, 2019)

thanks everyone and especially Lloyd for great advice.
I think I figured it out. No Lloyd, there was no crash, but maybe something dumber 
Thinking my process through I realized I measured the straightness of the d1-4 backing plate with a gauge mounted on the end box.  But I measured the bar in the chuck with a gauge on the saddle.

This immediately suggests the misalignment is between spindle and ways.
The lathe might be  a bit old (40years?) but it hasn't had much use, ways are clean and I believe spindle bearings are good.

Then I remembered...the lathe is on a  ply shed floor, and is a bit unsteady. But the shed is not mine, so I can't pour concrete or cut holes in the floor.  So I bought some slabs of 1/4” steel plate and a couple of weeks ago I slid them under both ends of the lathe. But I had no helpers so I had to lift each end separately with a pry bar, and hold the bar down with my foot while I bent double to slide the plate under - quite athletic.
In doing this I think I ‘bent' the join between the ‘box’ and the ways.  Makes sense?  Its a sheetmetal base, not cast.
(one day I should get/make a more solid base for it.)

So now the question:  is how do I find out and how do I fix it.
To calibrate, I’m guessing I need a long straight bar in the chuck, and two gauges at 90 deg on the saddle. Maybe one in a tool holder.
I guess I’ll figure hout how to align the ways with the spindle axis by adjusting mounting bolts, maybe shimming?

Thanks all, I really appreciate this supportive community.


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## Lloyd-ss (Mar 10, 2019)

Wow, I can hear the grunting and cussing while you were muscling that around.  How about first just checking the base to see if its level? Maybe a shim or 2 in the right place will get you back in business. Fingers crossed.


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## MRA (Mar 10, 2019)

If the spindle is out with the bed,  it'll bore tapered holes, so this might be a way to check?  On a previous (ancient) machine with a flat-top English bed I could make such an adjustment, but with my current V-way bed machine the headstock is either right, or something is Very Wrong!


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## Anatol (Mar 11, 2019)

Lloyd-ss said:


> How about first just checking the base to see if its level?.



yeah but,... the base is two sheetmetal cabinets, I'm not persuaded they're too rigid, I could have bent them a bit or put a tiny bend in the place where the headstock meets the ways. As far as I an see, the way to test is with a very straight bar I note chuck, and a couple of gauges.I don't have such a bar... I guess a foot of 1" drill rod would give me some indication.  

I lifted the far end of the headstock, so if theres a bend, its a 'valley' at the meeting of the headstock and ways. So I guess I could jack up the join with a screw jack?


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## Anatol (Mar 11, 2019)

MRA said:


> If the spindle is out with the bed,  it'll bore tapered holes,



I don't think I need to do that, I already know its not straight by putting a gauge on a straight bar. Or am I m missing something?


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## Anatol (Mar 11, 2019)

I'm not near the lathe right now but I had look at a diagram. Clearly the bed/ways are well attached to the headstock, I'll need to do some dismantling (taking off cover panels)  to find what screws to adjust and where to shim. Good practice I guess. Always learning experience


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## goldstar31 (Mar 11, 2019)

At the risk of further castigation, might I querulously ask whether the lathe bed is 'in twist' or not?

Over the years, I have written on this matter and seemingly no no avail.

Again, risking further censure, this sticking a rod in a chuck- and possibly cutting two test rings is not the answer to someone with a lathe -- which hasn't just come out of the factory.

True, I have a test bar with a No 2 Morse taper shank and I have a thing to cut ( hopefully) two identical rings. However, my lathes are 'new' or recently returned from being slideways ground.  ALL of them have been subject to having a precision spirit level put along the ways and across the shears- at least twice and the necessary adjustments made.

Be assured- there is nothing revolutionary or even new.  It is and always was standard practice.

My Sieg4 sits on a steel drip tray but  that lives on the top of a 1" topped computer desk whereas my Myford ML7B lives on a steel sheet drip tray on a steel lathe stand which is bolted down. 
That's not the end of things on a Myford because a 7 is out of balance because the motor- well, mine is  attempting to tilt everything backwards.   Once the motor was installed, I re-checked everything.

Somewhere in what I laughingly call my library, there is a similar sort of note by none other that Tom Walshaw writing as Tubal Cain  of his workshop in the English Lake District- where the ground under his lathes- isMOVING!

I hope that these comments might point the way to solving your own problem.

Norman


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## Lloyd-ss (Mar 11, 2019)

This is very interesting and enlightening. It is funny how someone else's comment or situation can make one sit back and evaluate their own situation.  I am new to the forum and trying to absorb and learn what I can from the wealth of knowledge that is freely offered, hopefully without being an annoying  pain to people. 

I have a Grizzly benchtop lathe similar to, but a bit smaller, to the lathe that Anatol is diagnosing right now.  It got me to pondering how my lathe is mounted, and then Norman's comments made me think even more about it. My lathe is 11 years old and has been setting in the same place for 4 years now. It is mounted on one of those old WW2 military office desks, reinforced, topped with a large piece of 1-3/4" thick solid core door, with the legs removed and now sitting on a solid box base of 2x6's. I very carefully leveled the top with shims placed under the 2x6 base when I did the initial installation. But the lathe itself is really just setting on its two 4"x6" rough finished cast iron pads about 36" apart, with a single 1/2" bolt thru the middle of each one. As Norman asked, is the bed twisted? Darn Norman, I am just having my first cup of coffee and now have a task to do because I don't know the answer to the question.

So I had to check it, and honestly, it only took about 30 minutes. I don't have a precision spirit level, but I do have a 4 foot carpenters level that has tight vials and is repeatable. I removed the rear chip guard from the machine so that the 4' level could lay across the ways. The chip guard only had 3 screws.  I wanted to lay the  level across the ways near the headstock, and then at the tailstock end of the ways. I used a pair of ground tool blanks, one on the flat of each way, to get the level above the V's. The tops of the V's aren't ground like the flats are. I wiped the ways and tool blanks clean and also stoned the bottom of the carpenters level in the middle 6" so that it would set repeatably on the tool blanks. I laid the level across the tool blanks at the tail stock end first, noting exactly how the blanks were placed and how the level was placed on top of them. The bubble looked to be centered perfectly between the lines, but with progressive eye glass lenses and old eyes it was hard to tell. I ended up putting a .010 feeler gauge under the level, on top of the rear tool blank to shift the bubble ever so slightly to the edge of a line. With an eye loupe I could see exactly how the bubble touched the line in the level. So I had my reference point. Then, again noting exactly how everything was placed, I moved the entire set-up to the headstock end of the lathe.  And guess what? Instead of a .010" feeler gauge, I had to use a .012" feeler gauge to get the bubble in the same alignment. Hmmmm. The tool blanks supporting the level are only 4" apart, so that is .0005" of twist per inch front to back, but it is spread out over the 30" spacing that was between my 2 measurement points. Does it matter? I don't know, but zero would certainly be better. And maybe I could "push" on the headstock with my hand and get it to move even more than that.  IDK. But shimming it to get the two ends level with each other ought to easy enough to do.

Norman, thanks for your thoughts, and Anatol, I apologize for my long windiness in your thread, but hope there is something useful in there.
Lloyd


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## mu38&Bg# (Mar 11, 2019)

The question is are you measuring runout or aligning the bed to the spindle? They are not the same thing.


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## goldstar31 (Mar 11, 2019)

dieselpilot said:


> The question is are you measuring runout or aligning the bed to the spindle? They are not the same thing.



Happily, first things first.  If you don't get the bed sorted out, the alignment of the spindle becomes nigh impossible.

If the bed is twisted at all, one must assume that Friend Pi will multiply the error when a longitudinal  cut is taken. I need not utter the word 'Ouch!' Surprisingly the twisted lathe bed  changes from a a rectangle to a part of a cylinder.   This is why people like Georg Schlesinger(Sp?) writes and writes and the whole thing is accepted by people who  are charged with getting things right.  If you want bed time reading, get stuck into Edward Connolly's Machine Tool Reconditioning- which is available on the 'net. A wet towel, a crate of aspirin and match sticks to prop eyes, but brother, that is the dog's doo daa's.

And somewhere, Dieselpilot, you will find that most spindles have a toe in-- and invokes the wrath of an instructor when resting elbows on convenient tailstocks.

Incidentally, I'm not an engineer but have family share certificates for failed machine tool manufacturers.

Repeating myself---- OUCH!

Norman


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## mu38&Bg# (Mar 11, 2019)

Norman, let's go straight to the point. How is spindle/chuck/tool/work runout related to bed leveling or spindle alignment? It isn't. So what did the OP measure/observe? You can level the bed and align the spindle all you want, but it won't fix runout.


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## goldstar31 (Mar 11, 2019)

If you are talking about the runout caused by a worn chuck, I agree but if you are talking about machining a a piece of work which should  emerge truly parallel   from a twisted bed,  I have respectfully disagree.

To attempt to  correct a worn chuck by grinding the jaws when the scroll is worn  only produces an accurate position in one diameter.  One needs something like a curvilinear  chuck to cut a scroll which will allow (say) three jaws to open and close throughout the chucks range- accurately.  Bazmak and I were happily prattling about soft jaws some time back.

I think that we fondly follow Euclid and imagine that everything follows straight and parallel lines but a machine tool improperly adjusted or worn- or Heaven forbid-- both,  certainly doesn't follow any of the Euclidean postulations.

I'm writing as someone who has scraped several lathes over the years. In fact, in the vdim and distant past I described in Postbag in 'Model Engineer' how  I reconditioned a friend's Myford ML7 which earlier was only fit to turn bananas.  It ended up with a reasonable accuracy of 'half a thous' runout at 6 inches on a homemade test bar.   I had to scrape a reference from a reference which came from 'Blancharding'  his worn lathe bed.

I hope that this throws a bit of light onto what is clearly a very misunderstood procedure.

Regards

Norman


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## mu38&Bg# (Mar 11, 2019)

I am not "talking" about anything. I asked for clarification of what was measured to give the proper answer.

All that typing and we still don't know what the OP actually did! Nothing you say is wrong, but I don't think it's the answer the OP needs, yet.

A: Did he use a dial indicator to check spindle/chuck/work runout?
B: Did he turn a piece of stock and measure diameter which showed taper?

The OP's first post in this thread implies he did A, while his post #5 indicates he thinks B is the problem.

This should bring up red flags if you understand how to inspect a lathe. As we know A and B are unrelated! I'm not sure Anatol understands this. This lathe has V ways and the chances of the headstock moving or being worn are extremely small.


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## goldstar31 (Mar 11, 2019)

dieselpilot said:


> I am not "talking" about anything. I asked for clarification of what was measured to give the proper answer.
> 
> All that typing and we still don't know what the OP actually did! Nothing you say is wrong, but I don't think it's the answer the OP needs, yet.
> 
> ...



Obviously, I  haven't a clue as to how the poster conducted his 'tests'.  Probably the proper test would be to rig a taut wire from the spindle to the tailstock 'poppet' and use a dial gauge on the saddle to record the deviations along the bed.   Seemingly, at the end of the day, the chuck- worn or otherwise seems to be somewhat irrelevant.

I suppose that. some 'dollar a dozen' lazer could be rigged up to  to find out what really is happening.
I recall 'Exactus' writing years ago in Model Engineer doing something similar which was entitled "Microscope  on the Lathe'  

I think that the original article still appears on the 'net. 
Of course, you are pushing an old man who to rack his almost 89 year old brain to find a solution  which really should be subservient to others who haven't macular degeneration like me.  The necessary information is, I 
believe, still available as I have suggested. 

In all sincerity I cannot condense a tome of more than 500 pages into a ' a few lines' of difficult for me to read  script.
Maybe someone else should have a go.

Regards
Norman


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## goldstar31 (Mar 11, 2019)

Thanks Lloyd ss. I didn't know that anyone was actually 'reading between the lines' or V ways.

Gosh

Norm


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## Anatol (Mar 12, 2019)

Thankyou Norman, Lloyd, dieselpilot for helpful advice. I'm afraid I've spent my available time tonight reading (some of) Edward Conolly's book on scraping (recommended by Norman). I thought it was only about scraping, but its a goldmine of machininst's knowhow-thankyou! So I only had time to gloss the thread.

I will return as soon as I have time, but meantime, let me summarise:  
A dial indicator (1 thou divisions) mounted on the headstock plate behind the chuck was used to check the chucks, radially and axially. The 'new' chuck was better than 2thou, the old chuck about 3 thou.
A rod locked in the jaws - sequentially of both chucks - was tested with the dial indicator in a mag base on the saddle - this showed the rod describing a cone. I believe this is called axial runout. The point of the cone originating about at the plane of the back of the chuck.
I understand that the 'datum' is different for the two readings. 
I am having trouble visualizing what kind of misalignment can result in the rod in the chuck describing a cone, with respect to the plane of the ways.

I have a precision level 0005/ft, I bought it on eBay and it was not packed well  . I checked the ways with this in three places (middle and at each end) rotating it 180 deg in each test location to (presumably) cancel error. The ways seem to have no (minimal) twist. BUT my methods may be sloppy. 

I will try the 'taught wire' test, maybe that will help me understand the problem better. 
It is also obvious I need to re-level the entire machine, and I know this can only be temporary due to the nature of the floor.

I am a beginner and am keen to learn. The exactitude of the machinist's art is something mere mortals cannot comprehend, and I must admit being a bit awe-struck by the precision that can be achieved by skill, precise method and concentration, using simple, but accurate, tools. I am also thoughtfully impressed by the fact that diagnosing such seemingly simple geometrical problems in the metal objects right in front of me can be as intellectually challenging as anything I've ever done. 
thanks again.


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## goldstar31 (Mar 12, 2019)

Initially, I'm delighted that you are working your way through 'Connelly'.  There is an enormous amount of valuable information which will take more than one reading to really appreciate. Nevertheless,  I'm sure that you will get there eventually. My suggested  use of a wet towel, aspirins etc came as a result of my own experiences. It's tough going.

Of course, the book is dated especially about the use of scraping tools and  diamond pastes and carbide scrapers are a great improvement to constantly honing  hss and carbon steel scrapers. Again, you will eventually find that things are not flat FLAT!  Also, there are now things like Moglice and Turcite that can build up  wear rather than having to scrape a long run of otherwise nigh perfect straight and unworn metal. So before you venture to correct things, think whether a dollop of filled resin might be the easiest alternative.   So the saddle of my Myford has had a layer of Turcite building  what was as rough as a badger's nether end!

As another idle thought, you might consider a more accurate way of measuring  tenths of thous instead of thous.

As the late and lamented George Thomas said  'No hairs are too fine to split!'

Above all, I wish you well

Norman


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## Lloyd-ss (Mar 12, 2019)

Anatol said:


> Thankyou Norman, Lloyd, dieselpilot for helpful advice. ................
> ...............
> I am a beginner and am keen to learn. The exactitude of the machinist's art is something mere mortals cannot comprehend, and I must admit being a bit awe-struck by the precision that can be achieved by skill, precise method and concentration, using simple, but accurate, tools. I am also thoughtfully impressed by the fact that diagnosing such seemingly simple geometrical problems in the metal objects right in front of me can be as intellectually challenging as anything I've ever done.
> thanks again.



Anatol, 
I quoted your last paragraph because it really struck a chord with me, especially your first sentence. Even though I have been doing this as a hobby for 10 years and consider myself very mechanically inclined compared to the "general public", I am totally humbled by the skill and knowledge of the participants of this forum. It IS intellectually challenging, and anything that is such, always presents a stage for lively interpretation and discussion. Anyone not familiar with the art probably doesn't understand that, but ask me about literature or music and I am totally clueless. 
Visualization of alignment issues is, for me, difficult, because they are so complex and there are so many variables to assess.  Machinists who have dealt with these issues can visualize it effortlessly and have their own self taught, self learned tricks. If Norman or dieselpilot  were there with you, I bet the problem would be solved in short order. Verbalizing and interpreting  it is a lot tougher, just like literature and music, LOL. But that is one of the reasons we love the challenge of machining. 

One somewhat related anecdote I'd like to share about visualization, if you will indulge me. I was installing trim around the roof of a small shed and my 6 year old grandson was over "helping". I had cut 2 identical rake boards for the gable end, and they were both setting on the saw horses, parallel to each other, so that they both looked the same. I installed one of them onto the left hand slope. I could see him studying the other rake board, which was laying totally in the wrong orientation for installation onto right hand slope. I asked him, "Khayden, I don't know if I cut this one the right way, I am not sure it will fit." He immediately said, "Sure it will grandpa, just do this." He held his arms straight out in front of himself and twisted them into a funny "X". He got it. I was proud.


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## goldstar31 (Mar 12, 2019)

Time to introduce that young man to what some of us call the Seven Liberal Arts!


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## Anatol (Mar 12, 2019)

goldstar31 said:


> So before you venture to correct things, think whether a dollop of filled resin might be the easiest alternative.
> 
> As another idle thought, you might consider a more accurate way of measuring  tenths of thous instead of thous.
> Norman



I've spent quite a lot of time with (epoxy) resins, as a boatbuilder. I've begun to experiment with custom composites, such a epoxy filled with graphite and short class fibers - this seems useful for self lubricating, non-corroding machinable bushings. 
I can. probably come up with a decent Moglice-like product, probably using bronze powder or aluminum powder. 

"measuring  tenths of thous" I've got a tenths indicator, didn't use it yet on this problem.


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## Anatol (Mar 12, 2019)

Lloyd-ss said:


> Anatol,
> I quoted your last paragraph because it really struck a chord with me, especially your first sentence. Even though I have been doing this as a hobby for 10 years and consider myself very mechanically inclined compared to the "general public", I am totally humbled by the skill and knowledge of the participants of this forum. It IS intellectually challenging, and anything that is such, always presents a stage for lively interpretation and discussion.
> 
> I asked him, "Khayden, I don't know if I cut this one the right way, I am not sure it will fit." He immediately said, "Sure it will grandpa, just do this." He held his arms straight out in front of himself and twisted them into a funny "X". He got it. I was proud.



Thanks Lloyd,
I've been designing and building for years, and am challenging myself to learn old school machining - no DROs. Not till I really understand it anyway.
Regarding the "X", this is a subject of great interest to me. "Embodied Cognition" or more colloquially, knowing through the body. Its a way of knowing that is less and less valued as we become more dependent on more sophisticated technologies. Hence  "no DROs" .


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## Anatol (Mar 12, 2019)

goldstar31 said:


> Time to introduce that young man to what some of us call the Seven Liberal Arts!



That 'young man' is approaching retirement age.


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## goldstar31 (Mar 12, 2019)

I was talking about the grandson!


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## Anatol (Mar 12, 2019)

goldstar31 said:


> I was talking about the grandson!



yeah, sorry of course you were. I laughed!


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## goldstar31 (Mar 13, 2019)

Back to lathe chucks and inaccuracy.

I'm wondering if this is a common fault  where the Number 1 shear is worn about 6" from the spindle nose.

I've had this on several Myfords

Regards

Norman


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## Lloyd-ss (Mar 13, 2019)

Anatol,
Your interest of embodied cognition prompted me to do some reading on the subject and although I found it intriguing and very plausible, I found the subject extremely difficult to sort out in such a way that I clearly understood the concept. The individual body-mind metaphors made sense to me, but I, because of the way my mind works I guess, was unable to assemble "the big picture" of the concept. It is in the realm of what I might call (for myself) philosophical thinking, which I have always found to be very difficult to decode. For me, visualization seems to be necessary for full understanding of almost any subject, and although I can visualize various examples of the concept, I cannot visualize the concept itself. I hope this explanation of my struggle and inability to understand makes sense. Something in my brain can't process that sort of structure. But, on the other hand, I am glad that my grandson's body-mind processing of the puzzle might have further gelled your understanding of the subject.
And just to stay on task for the forum guidelines, do you think there is something of the embodied cognition that makes some people intuitively better at machining and conceptualizing the projects that we make?
Lloyd


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## Shopgeezer (Mar 13, 2019)

I am getting the lathe going again after many years of inactivity and my first purchase will be a DRO. Old eyes don’t work anymore on teeny little inscribed lines and numbers. Give me those big glowing numbers. Same with micrometers and calipers. All digital. So much easier these days. It all makes me want to choose the lathe over the TV in the evenings.


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## Anatol (Mar 13, 2019)

goldstar31 said:


> I'm wondering if this is a common fault  where the Number 1 shear is worn about 6" from the spindle nose.



First, please explain what "Number 1 shear" is ? 

Second, early on in Conelly, he talks about "the Three Plate Method utilising Symmetrical Distribution of Error (See Sec 21.5)"
I went to 21.5 and comprehend the Three Plate Method, but, sadly, he makes no further mention of "Symmetrical Distribution of Error" . Do you, or anyone, know what this is or where can learn more about it ?
thanks!


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## goldstar31 (Mar 13, 2019)

Number 1 shear is the first  shear as you face the lathe. In an ordinary flat bed it is fairly obvious but in a Vee bed, it is  the first bit of the vee which faces the operator. The wear is caused by the predominance of working near the chuck/ collet/ faceplate.

The Three plates are ground with abrasive rubbing each face alternatively at random which progressively flattens each face until ANY face will ring to ANY other face-- or as some describe it, if glass is being used, three optical flats are created.

Is this any clearer?.

Norm

NB. Moving on somewhat, a 'reference ' is created on which to build up verticals and whatever. Happily, I broke off a note to Lloyd to go to a Masonic first degree( Entered Apprentice) rehearsal at one of my lodges.
Of course,  what I'm prattling about is  what was 14 year old 'schoolboy Euclid'
N


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## petertha (Mar 13, 2019)

I am not familiar with your lathe but I Googled Grizzly model G4003 because you suggested the similarity. If your head stock is separately mounted to the bed, then any rotational misalignment viewed from the top would explain what I think you are seeing. ie. if the DTI was mounted to the apron, registered to a test bar at an inboard position close to the spindle nose & zeroed. Then traverse the DTI/apron down the test bar (no spindle rotation). If it reads something different at the end of the test bar it could be purely related to the entire head stock being yawed. This has nothing to do with chuck centering, jaw grip, lathe twist or even spindle rotation. If you can get hold of a cylindrical test bar with matching MT# socket, stick that in the spindle with no chuck, eliminate all the middlemen & just traverse down the bar. If you measure discrepancy, this is a strong clue.

Typically on these Asian lathes there are bolts which secure the head stock down to the bed & there are also some lateral set screws which micro-adjust the head alignment. If during moving or just not set up properly the head has shifted and spindle axis is pointing inward or outward relative to bed axis, this is the issue I'm describing & needs to be corrected. Strangely, the G4003 manual does not discuss this & I cant quite see such screws on the parts diagram. It just talks about checking taper cutting via the tailstock offset which is a different matter down the road when the headstock alignment is first dealt with.

Now if your particular lathe is an all-in-one meaning the head stock is integrally cast with the bed, then disregard all the above. You have no means to adjust this other than what people have suggested - bed twist, chuck issues etc. Let us know what you see & better yet, some pics!


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## kwoodhands (Mar 13, 2019)

.

Now that you have a precision level , read the instructions  that came with it. The level has adjustments. You will find that this level is not comparable to a carpenters level. Much more sensitive. This level will indicate twist in the bed , if there is any. The level is place across the ways , NOT parallel to the ways. Thin shims , paper etc under the bed casting in one or more corners is done til the bubble is dead center. This can take hours , I spent most of the day leveling a friends Standard Modern lathe he got from a school in Canada.
After the lathe is leveled to the best you can get , then do the two ring test. You tube probably has a video on this, I haven't done it in years and do not want to describe it for fear of making mistakes. 
The ring test should show the lathe is level across the ways. Now test the bar in the chuck. Hopefully the chuck problem is solved, just an out of aligned lathe bed.

mike


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## mu38&Bg# (Mar 13, 2019)

As everyone is still assuming Anatol read a misalignment vs runout on his test bar. I will ask, What exactly was observed?

The below link shows runout of a shaft in a lathe. Is this what was observed? This is not the same as a twisted bed or misaligned headstock. I'm sure more suggestions will help, but let's make sure we're solving the right problem.


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## goldstar31 (Mar 13, 2019)

I'm assuming  an element of wear or misuse simply because  of Anatol having chuck problems on the original chuck and then buying a second hand chuck to 'replace it' on e-bay- and finding that it was just as bad.

There is 'something' that we all are unaware of. After all,  it is not  some ancient old lathe  that is being discussed.


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## Anatol (Mar 13, 2019)

goldstar31 said:


> The Three plates are ground with abrasive rubbing each face alternatively at random which progressively flattens each face until ANY face will ring to ANY other face-- or as some describe it, if glass is being used, three optical flats are created.
> 
> N



thanks, yes. I found the reference. Although in the text he points to 21.5, the discussion of Symmetrical Distribution of Error is at the beginning of 21.


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## Anatol (Mar 13, 2019)

Lloyd-ss said:


> Anatol,
> Your interest of embodied cognition prompted me to do some reading on the subject and although I found it intriguing and very plausible, I found the subject extremely difficult to sort out in such a way that I clearly understood the concept. The individual body-mind metaphors made sense to me, but I, because of the way my mind works I guess, was unable to assemble "the big picture" of the concept. It is in the realm of what I might call (for myself) philosophical thinking, which I have always found to be very difficult to decode. For me, visualization seems to be necessary for full understanding of almost any subject, and although I can visualize various examples of the concept, I cannot visualize the concept itself. I hope this explanation of my struggle and inability to understand makes sense. Something in my brain can't process that sort of structure. But, on the other hand, I am glad that my grandson's body-mind processing of the puzzle might have further gelled your understanding of the subject.
> And just to stay on task for the forum guidelines, do you think there is something of the embodied cognition that makes some people intuitively better at machining and conceptualizing the projects that we make?
> Lloyd



Hi Lloyd
"I found the subject extremely difficult to sort out in such a way that I clearly understood the concept."
that is probably because we are accustomed to thinking we have a 'mind' an a body' and they are separate and different. Thank Descartes for that. Embodied cognition starts from the premise that this simply isn't true. 
"It is in the realm of what I might call (for myself) philosophical thinking, which I have always found to be very difficult to decode."
yers, I find a lot of philosophy pretty abstruse too. But Embodied cognition is based in the common sense understanding of practices and experiences all makers have. 
"do you think there is something of the embodied cognition that makes some people intuitively better at machining and conceptualizing the projects that we make?"
All humans and animals cognize in an embodied way - we integrate internal and external senses - proprioception, vision etc. Some people, through inclination or vocation, refine it. Others are more disconnected from their bodies, we call them 'klutzes'


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## Anatol (Mar 13, 2019)

petertha said:


> I am not familiar with your lathe but I Googled Grizzly model G4003 because you suggested the similarity. If your head stock is separately mounted to the bed, then any rotational misalignment viewed from the top would explain what I think you are seeing. ie. if the DTI was mounted to the apron, registered to a test bar at an inboard position close to the spindle nose & zeroed. Then traverse the DTI/apron down the test bar (no spindle rotation). If it reads something different at the end of the test bar it could be purely related to the entire head stock being yawed. This has nothing to do with chuck centering, jaw grip, lathe twist or even spindle rotation. If you can get hold of a cylindrical test bar with matching MT# socket, stick that in the spindle with no chuck, eliminate all the middlemen & just traverse down the bar. If you measure discrepancy, this is a strong clue.
> 
> Typically on these Asian lathes there are bolts which secure the head stock down to the bed & there are also some lateral set screws which micro-adjust the head alignment. If during moving or just not set up properly the head has shifted and spindle axis is pointing inward or outward relative to bed axis, this is the issue I'm describing & needs to be corrected. Strangely, the G4003 manual does not discuss this & I cant quite see such screws on the parts diagram. It just talks about checking taper cutting via the tailstock offset which is a different matter down the road when the headstock alignment is first dealt with.
> 
> Now if your particular lathe is an all-in-one meaning the head stock is integrally cast with the bed, then disregard all the above. You have no means to adjust this other than what people have suggested - bed twist, chuck issues etc. Let us know what you see & better yet, some pics!



Thanks Peter
"I Googled Grizzly model G4003 because you suggested the similarity."
its pretty close, so is a Jett 1236 and a PM1236
"If your head stock is separately mounted to the bed, then any rotational misalignment viewed from the top would explain what I think you are seeing." "This has nothing to do with chuck centering, jaw grip, lathe twist or even spindle rotation."
yes, I think your analysis is correct
"If you can get hold of a cylindrical test bar with matching MT# socket, stick that in the spindle with no chuck, eliminate all the middlemen"
that would be nice, yers, I'd thought the same thing. But I don't have one  so I'll have to use what I can get. I will proceed as you suggest - after rechecking machine level and bed twist -using the biggest straightest piece of bar I can find.
"Now if your particular lathe is an all-in-one meaning the head stock is integrally cast with the bed,"No I believe its bolted on, but I have yet  to explore and find bolts. Tomorrow maybe. 
"Let us know what you see & better yet, some pics!"
ok, thanks again.


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## Anatol (Mar 13, 2019)

dieselpilot said:


> The below link shows runout of a shaft in a lathe. Is this what was observed?




yup, thats almost EXACTLY what I observed.
thanks.


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## petertha (Mar 14, 2019)

No harm at all verifying lathe twist first. Get that established beforehand. But don't proceed to jacking a foot & introducing compensation twist until you validate headstock/spindle alignment. If its out even a smidge, it can have a significantly larger impact & you will be chasing your tail twisting the bed or worse. To put numbers to it, if you measure 5 thou of deviation on a 12" test bar, that translates into a headstock angle rotation of only 0.024 degrees relative to the bed axis. Tiny! Those head stock jacking set screws are very sensitive. When I adjusted mine I figured out which way the head would unload & just by cracking one set screw & not the other it aligned itself perfectly. Yours may have been incorrectly set at the factory, drifted on its own through use or I have heard of a it developing after a machine move with a sling around the head.

Well meaning people are often eager to recommend shimming a foot (twist compensation) to reduce 'head stock taper cutting'. But I suspect this advice dates back to machines where the head stock is integrally cast to the bed & spindle bored 'very close' to lathe bed to begin with. If you have a lathe like that, great. But that is actually quite uncommon on typical current Asian hobby lathe offerings where the spindle is contained within a free floating gearbox block until its bolted down into position. So jacking the bed is introducing a second wrong to try & make a right. Now you have a twisted bed and a cocked head stock. So that's why I asked that question up front. Notice that none of this involves rotating the spindle. It is just measuring angular deviation along the center plane. The spindle could be running with zero TIR but that's not addressing a potential head stock alignment problem which is causing taper cutting which is relative to the bed ways.

A cylindrical test bar will work fine enough for what you are trying to solve. Just realize that you are introducing the chuck & jaw grip into the error circle. So re-clamp a few times & look for consistent measurements. I bought a very good value test bar off ebay like this. Not only is it good for headstock work, it may also fit your tailstock hopefully & be beneficial there too which is the next thing to dial in. But first things first


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## petertha (Mar 14, 2019)

dieselpilot said:


> The below link shows runout of a shaft in a lathe. Is this what was observed? This is not the same as a twisted bed or misaligned headstock. I'm sure more suggestions will help, but let's make sure we're solving the right problem.




Hmm.. now that is interesting. But I wonder what we are looking at? It doesn't look like a test bar, it looks like stock that was chucked, heavily turned & now measuring deviation. Did it just stress relieve and go 'bwang'? That would account for DTI accurately mapping a banana. You can see the remnant of a nub on the end of of the bar. Maybe the parting operation applied bending force & it distorted? We need to see Season-1. Where was tail stock in all this? How hot were the chips? Who is the mysterious alloy? LOL


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## petertha (Mar 14, 2019)

My lathe if its helpful. The grainy pic with the 2 arrows are the jacking screws.


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## goldstar31 (Mar 14, 2019)

If I recall, Georg Schlesinger advocated a hollow test bar to minimise the droop from the weight of the test bar.

Again, he  produced a set of tests for machine tools including lathes but and this is a BUT, never included lathe chucks  and especially second hand chucks of unknown provenance!

So, as I said before, let us follow an internationally recognised test procedure rather than the seemingly 'hit and miss' procedure which most of us are trying to  examine and hopefully , correct.

Norm


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## mu38&Bg# (Mar 14, 2019)

The video was simply to make sure the correct terminology is being used to describe the problem (runout increasing away from the headstock per post #1). The problem in that video is severe, but it was short and to the point. I don't care how it got that bad.

Why muddle the real problem which is spindle/backplate/chuck runout, with aligning the bed/headstock? As I said in my first post, runout  and alignment are UNRELATED. I'd like to see someone use an indicator on at test bar that runs out .030"at  4" from the chuck (per post #1) to align a bed/headstock, what fun! Remove the headstock, ship it to me and I'll measure it to find the problem, no bed required.

I assumed( in error) that the intent of this thread was solve the actual problem. I understand the lathe setup process, though I can't throw any of these old names out there (except Moore).


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## petertha (Mar 15, 2019)

I think we are lacking a clear picture of what deviation is actually being measured, which leads to guessing or interpretation. Throw in some non-standard terminology, or possibly standard terminology applied incorrectly and things can get messy.

Here is where I'm coming from. Going back to post#1 he says: *A rod set in the jaws describes a cone. Close to the jaws, the rod is 10-15 thou out, but 4” down the rod the error increases to 30 thou or so. Tracing back along the rod into the chuck, this would suggest the minimum error on the rod - the point of the cone - would be back inside the chuck - if you could measure it.*


*describes a cone*. A cone is a 3D object so kind of infers the test bar is rotating. But he never actually says rotating. He took a measurement close to the jaws and 4" down the rod. I can visualize a cone if
1. the test bar was straight but gripped in the chuck at an angle offset to spindle axis. This could be the jaws, the chuck, the mounting back, the spindle nose.... He said he replaced the chuck with another & got similar results. So maybe the mounting back or spindle nose is suspect if they are common to both chucks. I suggested removing all the rotating hardware to eliminate them & insert an MT test bar into the spindle socket. He doesn't have one, so the jury is out
2. the test bar is bent outboard of the chuck. I assume this is not the case because even rolling on a plate would show 30 thou big time


*t*_*racing back along the rod into the chuck, this would suggest the minimum error on the rod - the point of the cone - would be back inside the chuck - if you could measure it.*_
- this is just a guess, maybe I'm 100% wrong. It suggests he is just tracking a DTI down the bar, no spindle rotation. So I will volunteer this sketch as one possible interpretation. This is why I asked if he has a detachable head stock, which he has.
- this form of misalignment under spindle rotation does not describe a cone, but it would certainly cut a CONical taper. Is that what he meant?
- point 1 on sketch, is that what he means by point of cone would be back inside...?
- now just considering this mode of yawed head stock, how do we interpret when someone says 'runout'? If the test bar is 100% concentric to spindle axis, there is no runout between those components on that basis. But there is runout of the test bar relative to lathe bed axis if we introduce that aspect in real life machining. So which are we talking about? There probably is a precise definition or we should use extra words to be clarify. Google explanations are somewhat ambiguous.

Hopefully the OP will delve into issue & offer some more insight.


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## Cogsy (Mar 15, 2019)

Time to throw my 0.02 in. The way I read the first post makes it clear that these measurements are being performed on a rotating bar. Firstly, Anatol says "A rod set in the jaws describes a cone" which in normal speech would indicate revolution, however the real proof is his two statements "Close to the jaws, the rod is 10-15 thou out, but 4” down the rod the error increases to 30 thou or so" and " the minimum error on the rod - the point of the cone - would be back inside the chuck - if you could measure it". From this, we can see Anatol has not set his zero on his indicator at any point along the bar and simply measured misalignment, but is checking actual runout of the revolving bar at different points. If he was measuring misalignment of the bar over 4" of travel then the first point he measures would be 'zero' and the 'point' of the cone would not be within the chuck. He could not possibly have a figure of "10-15 thou" at the jaws, he could only give a difference figure like '20 thou over 4 inches'. Even if he was measuring a taper on a piece he had turned, the point closest to the jaws would still be his 'zero' point.

As Dieselpilot has been saying all along, no amount of headstock misalignment or bed twist can induce runout as Anatol is describing. It seems evident that the problem lies in the spindle nose, chuck backing plate or chuck itself. Except that he's likely checked for it already, I'd suspect a burr or maybe a small chip in the backing plate/spindle nose register could be a likely cause.


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## Anatol (Mar 15, 2019)

dieselpilot said:


> I assumed( in error) that the intent of this thread was solve the actual problem. I understand the lathe setup process, though I can't throw any of these old names out there (except Moore).



Tanks Dieselpilot - No error. I am very keen to get my lathe straight again (otherwise its useless). I'd like to get it very straight - straighter than in was.  (I am also interested to learn the history of this art.) 

To recap - I am afraid I induced this error by jacking up the headstock with a prybar, as noted in a previous post.
To clarify -  the measurements of 'runout' and the description of the cone described by the bar were with the bar in rotation. 

Cogsy said "As Dieselpilot has been saying all along, no amount of headstock misalignment or bed twist can induce runout as Anatol is describing. It seems evident that the problem lies in the spindle nose, chuck backing plate or chuck itself. Except that he's likely checked for it already, I'd suspect a burr or maybe a small chip in the backing plate/spindle nose register could be a likely cause."

The backing plate (camlock D1-4), as noted, runs quite true, within 2thou radically and axially. But two different 3 jaw chucks present very similar measurements, so a bit of  grit in the chuck jaws or backing plate seems unlikely, especially since I had the jaws off one chuck and cleaned and reinstalled them. But I'll check again.

I'd like to pause this discussion until I have time to level and measure and calibrate the whole lathe. 
Thanks to everyone who's lent their experience and intelligence to this thread.


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## goldstar31 (Mar 15, 2019)

I strongly suspect that your mention of  a whole 2 thous  on the backplate is way way--excessive.
Again, I seriously wonder about whether the spindle is bent, slack or worn or perhaps the bearings are 'shot'

Returning to your desire to 'learn more', I would  print out the recommended tests for lathes in Georg Schlesinger's book which is available as a pdf  on the 'net.

Looking at my library of measuring 'tackle', I  have a properly ground  test bar made from a worn out reamer with a good No2 Morse taper shank but I have also one of these bars of any old piece of ms rod which has two  'rings' machined in it- one close to the chuck end and the other as far out as bar itself which is cut  without tailstock support and then  both rings 'miked' to determine whether the they of the same size .

If they mike  OK, all is well but if they don't you have  a long series of tests to determine what is causing the dissimilarity in results. 

Seemingly people have forgotten that a soft centre in the spindle is always recut before working between centres.

Ot. LOL people don't know that 'soft centres' are available- apart from in boxes of chocolates LOL.

Norm


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## ShopShoe (Mar 15, 2019)

Anatol,

I've been following this discussion and I applaud your decision to stop and reconsider what all is going on and to establish some kind of a baseline for further changes.

It's too easy to "chase your tail" trying one thing, then another, until you get things so muddled that it seems nothing will work out.

One thing I don't see in your description is the history of your lathe and if is possible some of the problems may have come from a previous owner. Also, was there an "event" in the lathe's operation before you measured the originally-posted problem. I know you said there was not a crash, but maybe something else. (And I'm sorry if you did post those things and I missed them.)

Everyone else,

(A rant of my own, more like a gentle chiding, and meant to be taken lightly)

Everyone's input is valued, as that is what makes us all better at what we do. However (gulp), I find it tedius when the original poster in any thread gets relegated to third person while independent debates get started on the "proper" way to do someting that may or may not be an actual part of the issue under discussion. Thank you everyone for the reference works cited and for the experiences recounted, but let's watch Anatol work through this.

I had to say it, please don't kill me

--ShopShoe


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## bazmak (Mar 15, 2019)

You don't need an accurate level to check the bed twist.Just do the 2 ring machining
and adjust the /remove the bed twist accordingly.You will need riser blocks.
When I did my 3 no ml7s and 1 no super 7 recently I only needed to adjust the risers twice
for each lathe.When the bed twist is removed the lathe will machine parallel so you know the twist is removed
why then check it with a level.


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## Anatol (Mar 15, 2019)

Thanks all
Thanks Norm - Schlesinger downloaded
FYI - no nonsense link here-https://springfieldarsenal.files.wor...hine_tools.pdf
Thanks Shopshoe for sage words.
signing off on this thread till I have more tangible results.


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## tjwal (Mar 15, 2019)

Your run out problem is related to the spindle nose and chuck and not spindle alignment. Others have posted what to look for in that area.

In any case you may want to check your alignment as well.  I’d do that as a first step.  I use “Rollie’s Dad’s Method” to  check and adjust the spindle alignment. Simply put the method determines the axis of the cone that you described in your first posting.
 You need a dial indicator, micrometer and a reasonably straight bar.  Although a nice round straight bar helps it is not necessary. If it is ‘near’ precision ground then you don’t even need the micrometer.


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## petertha (Mar 15, 2019)

Cogsy said:


> I read the first post makes it clear that these measurements are being performed on a rotating bar. Firstly, Anatol says "A rod set in the jaws describes a cone" which in normal speech would indicate revolution, however the real proof is his two statements "Close to the jaws, the rod is 10-15 thou out, but 4” down the rod the error increases to 30 thou or so" and " the minimum error on the rod - the point of the cone - would be back inside the chuck - if you could measure it". From this, we can see Anatol has not set his zero on his indicator at any point along the bar and simply measured misalignment, but is checking actual runout of the revolving bar at different points. If he was measuring misalignment of the bar over 4" of travel then the first point he measures would be 'zero' and the 'point' of the cone would not be within the chuck. He could not possibly have a figure of "10-15 thou" at the jaws, he could only give a difference figure like '20 thou over 4 inches'. Even if he was measuring a taper on a piece he had turned, the point closest to the jaws would still be his 'zero' point.



I think the scenario you are describing is what I've suggested might be one possible explanation. Here is a corresponding sketch to help visualize that specific scenario. And even this is simplified. The test bar could be gripping out of alignment in a 2D plane, or just as easily in 3D space. 
_petertha> I can visualize a cone if 1. the test bar was straight but gripped in the chuck at an angle offset to spindle axis. This could be the jaws, the chuck, the mounting back, the spindle nose.... He said he replaced the chuck with another & got similar results. So maybe the mounting back or spindle nose is suspect if they are common to both chucks. I suggested removing all the rotating hardware to eliminate them & insert an MT test bar into the spindle socket. He doesn't have one, so the jury is out_​
Now if the OP confirms this is indeed how he conducted the test & measured results, then we are getting somewhere. Maybe not a solution but going down the right path. If he says, No that's not what I meant, then he needs to elaborate or clarify the test conditions so that we get a better picture. Or through Q&A perform a different confirming test to further narrow down the problem. If this particular scenario turns out to be the sole culprit, then yes, it has bugger all to do with lathe twist or spindle axis misalignment. Those 2 conditions could be perfect & still exhibit the same measurement deviation right? But they are easy checks to perform & potentially eliminates other problems because of possible interactions.


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## petertha (Mar 15, 2019)

Anatol said:


> The backing plate (camlock D1-4), as noted, runs quite true, within 2thou radically and axially. But two different 3 jaw chucks present very similar measurements, so a bit of  grit in the chuck jaws or backing plate seems unlikely, especially since I had the jaws off one chuck and cleaned and reinstalled them.



If your D1-4 back plate was out .002" radially and you happened to have a 100% perfectly radially concentric  chuck + jaws + test bar, then you would see the same 0.002" radial runout on the test bar and it would be a constant 0.002" down the length. In reality all these mating surfaces have tolerances which could work collectively for you or against you depending on the arrangement orientation. If the back plate was out 0.002" and the chuck rear recess (or bolt up) was out 0.002", they could add up to max 0.004" runout on test bar if phased collectively, or min zero runout if phased in opposition, or anything in between depending on the orientation.

Now if you have angular discrepency between the back plate & chuck, this would cause more like what you are observing which is an increasing runout along the test bar. Similarly If the backplate + chuck body are perfect but the jaws are gripping the test bar at some angle, that would be a similar net effect.

What is confusing is you seem to be getting similar results with both chucks if I understand, so its pointing to problem with the backplate face. If you had  (that same MT socket test bar we keep talking about! LOL) you could insert the test bar in the spindle, grip the test bar with the chuck jaws in reverse (the chuck is facing the spindle) and measure runout/deviation of the rear face of the chuck which at least confines the error to chuck body and/or jaws.


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## Cogsy (Mar 15, 2019)

petertha said:


> I think the scenario you are describing is what I've suggested might be one possible explanation. Here is a corresponding sketch to help visualize that specific scenario. And even this is simplified. The test bar could be gripping out of alignment in a 2D plane, or just as easily in 3D space.
> ​


​
This is exactly what I meant. Anatol has now confirmed his run out measurements are true measurements of run out (ie deviations in the shaft position through rotation). In your sketch the dotted red centre line is the axis of rotation and is (theoretically at least) the centre line of the spindle. This axis of rotation is not at all influenced by its alignment with the bed itself, nor bed twist, wear, etc., in terms of run out. The dial indicator making the measurements could be suspended from any structure rigid enough to support it and would yield the same information - namely the deviation of the shaft from the centre of rotation due to the shaft being misaligned with the axis of rotation. Misalignment with the bed/bed twist will result in deviances in turned shaft diameters but will not result in run out. We take this to the extreme when we use things like taper turning attachments to purposely turn non-parallel to the axis of rotation but the resulting shaft remains centered around the axis of rotation. 

If this exact issue were being described in a mill rather than a lathe, with a cutter exhibiting more run out the further it was measured from the collet/holder, we would not expect tramming the mill to have any effect on the issue. Having a perfectly level and straight lathe bed is an admirable desire but it cannot help with this current problem.


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## goldstar31 (Mar 16, 2019)

Assuming everything eose on the lathe is correctly aligned and unworn, off setting the  spindle  is little difference to using a taper turning attachment. 

Using a piece of bar 10" long instead of a sine bar and offsetting it by a quarter of an inch creates what Morse intended for his Morse tapers. Sadly,  his operatives couldn't measure accurately but that is where it all started.

Another way of creating a truncated cone which Anatol is experiencing .
 To think that years ago I was promoting how to cut a taper and now  how to correct one.LOL

Norman


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## DJP (Mar 16, 2019)

I'm still thinking that the problem is worn 3 jaw chucks. I have placed a shim under one jaw to correct runout and have bored the jaws to remove runout for that diameter of work piece. Multiple worn chucks doesn't help. My frustration was only solved with a new chuck or use of a 4 jaw. I would be interested if this runout problem being discussed still exists with a 4 jaw chuck. That might convince me that the problem is deeper in the machine bed or spindle.


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## petertha (Mar 16, 2019)

Yes, worn jaws. Or jaws maybe inserted in the wrong numbered slots, although one would think that should be dramatically obvious. I heard a similar story where a guy bought a used chuck & having runout issues no matter which combo of jaw positions he tried, only to discover owner #1 replaced 'some' jaws with lookalike chuck. But the difference was he always had some runout, but it was constant down the test bar so the jaws were parallel but displaced from center differently between them. The OP's issue is increasing runout down the test bar suggesting the jaws are imparting an angle to the test bar when tightened. Some folks here have already touched on jaws but we really haven't heard how they were tested. The OP said same results on a second 3J chuck he tried, so what are the odds?

I was trying to think of a way to get a quick visual on jaw grip. Like maybe blue the test bar, clamp the jaws, remove & examine. If you don't see 3 consistent bands of  grip mark impression or some kind of suspicious pattern like the toe of one jaw & heels of the other two, maybe that is telling you something? I've never done it so casting out as idea.

If the 4J were made to run true (ish) near the chuck jaws but had the same increasing runout on the outboard section test bar, then it would again point to something upstream like a back plate issue. Probably the simplest thing right now is just borrow a known good D1-4 chuck + backplate assembly & eliminate 2 of his middlemen altogether. If it has 0.002" constant runout on the borrow lathe, then it should probably be close to that on the OP's lathe if the spindle nose & D14 tightening mechanism is in good shape.


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## goldstar31 (Mar 17, 2019)

It would be interesting if we had a report of the outcome  from the use of his independent 4 jaw chuck or perhaps his face plate.  I would reasonably expect that a drill chuck would not hold a test bar of sorts.

Just a thought or two looking  again  after discussing the problem with a 92 year old  mate of mine.

Norm


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## Anatol (Mar 20, 2019)

I told you I would return! 
Our story so far : similar substantial runout on two 3jaw chucks and a collet chuck, with the same 9" piece of 1" cold rolled bar in.  
The plot thickens, but tjwal, petertha, cogsy and norm are hot on the scent! (exciting isn't it?)

The 'origin' of the observed swept cone of the bar in rotation is back about the point of the fwd spindle bearing.  So I thought I should check for  worn spindle bearings or a bent spindle.  So today I pulled the back cover off the headstock and put not one but two indicators on the aft end of the spindle, about 120 deg from each other - one 'thous', one 'tenths'. Both ran dead true! No needle movement except over a spot of varnish or something on the shaft. I was amazed. I also put a 3' bar in the collet chuck and tried to wobble it, to check for bearing slop. Rock solid. So this is heartening. 

Suspicion is now directed at the spindle nose/back plate. 

One of the cam locks (?) on the spindle nose would tighten too far. So I adjusted the relevant camlock pin, and tried again. This time I put an indicator on the bar in the chuck as I tightened the cam locks. I could see runout diminishing as I tightened. So I really torqued the camlocks and it did reduce the runout, but not into acceptable range. 

I guess my next move is to try to shim the backplate to get the bar straight (I also need to buy/get a precision ground bar.) Since I get much the same error on all chucks, I suppose I may need to shave off the spindle nose plate. Not something I'm going to rush into!

In the meantime, I want make sure I understand the camlock system. The locks simply pull the chuck back plate hard up against the spindle surface - right?
 Can the locks and pins themselves effect alignment if they're adjusted right? 
The spindle nose  has three 'locks' and three cap screws. I took one out this revealed a spring down a well. But that 'well' or hole does not see to contact with the lock part. What is the function of the stuff under the capscrews? Can the locks be adjusted? 

thanks all!


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## goldstar31 (Mar 20, 2019)

Is the mounting face for the chuck FLAT? It would help if you removed all the bolts and whatever and lightly blue the back of the chuck and  use it to find the possible high spots.


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## Hopper (Mar 20, 2019)

Anatol said:


> ...
> 
> Our story so far : similar substantial runout on two 3jaw chucks and a collet chuck, with the same 9" piece of 1" cold rolled bar in.



How do you know that piece of bar is not bent or deformed? 
Have you tried other pieces? Or some ground bar out of a computer printer etc.?


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## petertha (Mar 20, 2019)

Essentially yes, the camlock pulls together the tapered recess of the back plate or chuck or whatever to the corresponding spindle nose. And this could entirely be your problem if either/or are not matching.
To clarify, when you replaced from chuck A to chuck B & observed pretty much same runout issue, did you mean you bolted 2 different chuck BODIES to the same backplate? Or did you mean each chuck assembly had their own backplate. I assumed the latter. it makes a big difference. If you bolted chuck B to the same backplate then you havent really eliminated the backplate as the problem source. Thats why I suggested the easiest thing for you to do is borrow a friends complete D1-4 chuck/backplate assembly & bolt mount it. If he had 0.002" runout, yours should be comparable.

I bought a new D1-4 face plate backplate & turns out it had a partially finished spindle nose recess. So despite D1-4 tightening, it was not being clamped mated co-axially or co-radially to the lathe spindle, it had a wobble. A quick check is to blue one of the surfaces, clamp up, remove & look for partial transfer pattern. Its not bulletproof but might give you quick insight.


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## Anatol (Mar 20, 2019)

goldstar31 said:


> Is the mounting face for the chuck FLAT? It would help if you removed all the bolts and whatever and lightly blue the back of the chuck and  use it to find the possible high spots.


 
"Is the mounting face for the chuck FLAT?"

this is at the question isn't it 

> lightly blue the back of the chuck and  use it to find the possible high spots.

and if I did it with three chucks, I'd approximate Whitworths method !

If I establish that the spindle nose plate  (if that's what you call it) is not 'flat'  - or -  not perpendicular to the spindle axis, the remedy is the same right - face off the plate? 
What is correct procedure? If the line of the spindle axis is  not parallel to the plane of the ways,  will faced surface still be perpendicular to the axis of the spindle? I think it will but  I'm having trouble visualizing this.


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## Anatol (Mar 20, 2019)

Hopper said:


> How do you know that piece of bar is not bent or deformed?


 
It really doesn't matter at present - correct me if I'm wrong -  since I'm just getting relative, indicative values - deflection  through a 360 deg swing. As my wise friend Tom noted - you can draw a perfect circle with a bent stick.

" Or some ground bar out of a computer printer etc.?"
nice idea. where else in junked machinery can one find precision ground bar?


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## Anatol (Mar 20, 2019)

petertha said:


> Essentially yes, the camlock pulls together the tapered recess of the back plate or chuck or whatever to the corresponding spindle nose. And this could entirely be your problem if either/or are not matching.
> To clarify, when you replaced from chuck A to chuck B & observed pretty much same runout issue, did you mean you bolted 2 different chuck BODIES to the same backplate? Or did you mean each chuck assembly had their own backplate. I assumed the latter. it makes a big difference. If you bolted chuck B to the same backplate then you havent really eliminated the backplate as the problem source. Thats why I suggested the easiest thing for you to do is borrow a friends complete D1-4 chuck/backplate assembly & bolt mount it. If he had 0.002" runout, yours should be comparable.
> 
> I bought a new D1-4 face plate backplate & turns out it had a partially finished spindle nose recess. So despite D1-4 tightening, it was not being clamped mated co-axially or co-radially to the lathe spindle, it had a wobble. A quick check is to blue one of the surfaces, clamp up, remove & look for partial transfer pattern. Its not bulletproof but might give you quick insight.



"did you mean you bolted 2 different chuck BODIES to the same backplate?"

3 chucks, each with its own backplate. 
(In the process I discovered that camlock pins come with both imperial snd metric threads. In USA, metric threaded camplock pins seem rarer and more expensive.   Anyone know of a reasonable supplier? )

"Thats why I suggested the easiest thing for you to do is borrow a friends ..."

Who has friends ? That's why I come here (joke). No machinist friends, at least not with D1-4 

"complete D1-4 chuck/backplate assembly & bolt mount it. If he had 0.002" runout, yours should be comparable."

I may also be able to fool around swapping backplates among chucks. I also have a e1-4 4 jaw, but its such a beast - over 12" dia" I didn't want to heave it around when I had others to test with 
and per Norm, blue is the next test, but I'll also try shims to straighten the bar up


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## Cogsy (Mar 20, 2019)

Anatol said:


> It really doesn't matter at present - correct me if I'm wrong -  since I'm just getting relative, indicative values - deflection  through a 360 deg swing. As my wise friend Tom noted - you can draw a perfect circle with a bent stick.


In this case it does matter as you're holding one end of the potentially bent stick. Imagine fixing one end of a banana at a point in space (the chuck) and rotating it around the centreline of that fixed end. The other end is going to describe a huge arc, reducing towards the chuck jaws, which is comparable to what you are experiencing. The end of the banana will be describing a circle but you will be getting a lot of deflection in the 360 degree swing.

This is relatively easy to check though. Put the bar in place and mark the extreme point of deflection. Then loosen the chuck slightly, rotate the bar 180 degrees and retighten the chuck. Now find the maximum deflection again. If it matches with the previously marked point on the bar then it's a bent bar, but if it stays relative to the chuck/spindle then the bar is not your issue.


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## Hopper (Mar 20, 2019)

Anatol said:


> It really doesn't matter at present - correct me if I'm wrong -  since I'm just getting relative, indicative values - deflection  through a 360 deg swing. As my wise friend Tom noted - you can draw a perfect circle with a bent stick.




If the bar is bent, the end will move around in a circle, causing your dial indicator to show runout. even if the chuck is running dead true. An out-of-round piece of bar will show a runout reading right next to the jaws, even in a perfect chuck. 

Other sources of ground bar includes gudgeon pins from car engines.


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## petertha (Mar 21, 2019)

Anatol said:


> If I establish that the spindle nose plate  (if that's what you call it) is not 'flat'  - or -  not perpendicular to the spindle axis, the remedy is the same right - face off the plate? What is correct procedure? If the line of the spindle axis is  not parallel to the plane of the ways,  will faced surface still be perpendicular to the axis of the spindle? I think it will but  I'm having trouble visualizing this.



Normally that is exactly how you prepare a semi-machined chuck back plate blank for mounting a chuck. It has a pre-machined internal tapered center hole profile that matches the spindle nose and the D1-4 pins. Tightening the D1-4 mechanism pulls the backplate in flush to the spindle, that fit has to be perfect to begin with. Turn the OD + face + lip/boss to match the recess in the chuck back plate. Drill mount holes & mount the chuck. If the chuck was accurate meaning jaws are true to the machined recess on the back & your backplate machined tolerance are good, it assures the best fit. 

Similarly it is common to take a skim pass across a face plate to true it.

But in your case I would not recommend this specifically because you haven't come up with a solution yet. If for example your spindle nose is egged or distorted, then when you mount a perfectly good backplate / chuck, it has the potential of mounting differently every time. So machining it 'true' probably wont be repeatable next time you mount it & you are chasing your tail. I feel like if you tried 3 independent backplate / chuck assemblies with the same runout problem its statistically looking very slim that your issue is chucks & back plates. It must be aft of that - the spindle nose or the D1-4 draw  mechanism or the spindle itself.


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## Anatol (Mar 21, 2019)

Cogsy said:


> In this case it does matter .... The end of the banana will be describing a circle but you will be getting a lot of deflection in the 360 degree swing..



You are right of course, its obvious. Thankyou, and apologies to Hopper. (The only thing I can say in my defense is that I was on a heavy dose of painkillers at the time.) I have made the measurements with several bars - of different diameters - and got similar results, but will do the test your recommend. I've also ordered a 1" precision ground bar.


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## goldstar31 (Mar 21, 2019)

Perhaps a couple of dial mikes reading in tenths???????


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## Anatol (Mar 21, 2019)

petertha said:


> I feel like if you tried 3 independent backplate / chuck assemblies with the same runout problem its statistically looking very slim that your issue is chucks & back plates. It must be aft of that - the spindle nose or the D1-4 draw  mechanism or the spindle itself.



Thanks, this is my reasoning too, but I want to be very sure before I start hacking up my spindle nose. If I can straighten one or more chucks with shims between nose and back plate, this will determine that the issue is at that mating surface - right? Then I should measure the nose axially and radially, with as precise a device as I have - tenths.

A more general question - If I use the fwd end of the headstock as datum, this measurement will be wrt spindle axis.
If I measure off the ways, cross slide or tool post, I'll introduce a potential error IF the spindle axis is not parallel with
the plane of the ways.

Thankyou also for all the explanatory pics and diagrams.


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## Anatol (Mar 21, 2019)

goldstar31 said:


> Perhaps a couple of dial mikes reading in tenths???????



Not quite sure what this is in response to. I have a couple mikes. How do you suggest I use them in this context? 
thx!


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## goldstar31 (Mar 21, 2019)

Anatol said:


> Not quite sure what this is in response to. I have a couple mikes. How do you suggest I use them in this context?
> thx!



You have or should have accessed the lathe test charts in Schlesinger which shows the way 2 dial gauges are used in several tests. Whether they are 'fine' enough is a answer that only you can supply.
You test the lathe according to -say- Schlesinger and if corrections are required you are the only person  to literally get on with revising the alignments discovered. 

We can only do so much. The rest is really up to you.

Norman


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## Cogsy (Mar 21, 2019)

Anatol said:


> A more general question - If I use the fwd end of the headstock as datum, this measurement will be wrt spindle axis.
> If I measure off the ways, cross slide or tool post, I'll introduce a potential error IF the spindle axis is not parallel with
> the plane of the ways.


I'm not sure why you would be measuring from any datum point for runout, all you need is a fixed point to take measurements from (i.e. your indicator should be secure when you take a reading). You're not going to be able to measure relative distance anywhere near as precisely as runout with an indicator where you're measuring differences rather than absolutes. 

You mentioned you have ordered a ground bar, hopefully it has an MT taper you can fit directly to your spindle. This bar will simply amplify any runout issue with the spindle and allow for easier measuring with indicators. If it runs true to your spindle bore then the problem narrows down to the spindle register, chuck backplates or chucks themselves. It will certainly get you closer to a solution.

To be honest, if this is a new error I can't see it being a bent spindle without some major event occurring. My money is still on the chuck/backplate/spindle interfaces as the problem.


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## DJP (Mar 21, 2019)

I am curious if this lathe was purchased used. I recently bought a quality 4 inch mechanic's vice at a deep discount only to find that it was bent. The jaws wouldn't close square and the threaded shaft would bind. I returned it for a refund and vowed to be more careful before taking home a bargain. 

Is there a possibility that your lathe was dropped during transport? Can you use the tail stock with a live centre to see alignment problems deep in the casting?

Your only solution may be to shim the head stock to get it close enough.

I'm sure that we would all like to see this issue resolved.


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## petertha (Mar 21, 2019)

Anatol said:


> If I use the fwd end of the headstock as datum, this measurement will be wrt spindle axis. If I measure off the ways, cross slide or tool post, I'll introduce a potential error IF the spindle axis is not parallel with the plane of the ways.



The 2 important surfaces that the camlock system registers to a corresponding mounted accessory on are the tapered cone (end of red arrow) and the rear face (end of green arrow). The nose front (orange arrow) doesn't contribute anything. Notice this back plate adapter is just a hole, it is not in contact with the lathe spindle. So when back plate & spindle are mounted together, cones coincide with one another and the faces are maybe 0.001" apart constant offset. Tightening the cams then bring the faces together. Ideally in a nice fitting arrangement the back plate has just a teeny bit of 'stick' &then pops off. Its a delicate fit.

So as pointed out ^above^ it matters not where you mount the DTI when checking the lathe as long as it is fixed. You are rotating the spindle & looking for deviation. For example if the spindle cone is not circular the DTI will wander in & out showing this deviation. Same thing with the nose flange face.


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## DJP (Mar 22, 2019)

With this cam locking system of retention it may be prudent to tighten the cams in stages. Tighten each cam to 1/2 of the final torque, then tighten them again in sequence coming closer to the final torque applied which should be equal for all cams. You may need a small torque wrench to do this properly. The process is consistent with tightening wheel nuts of a car to ensure that the rotors are not stressed adding runout.

Just one more idea for discussion to solve this issue.


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## Anatol (Mar 22, 2019)

goldstar31 said:


> We can only do so much. The rest is really up to you.
> 
> Norman



thanks Norman, I know. This community is very knowledgable and generous. 
I have Schlesinger
I was jut confused about your reference to 'mikes'


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## Anatol (Mar 22, 2019)

Cogsy said:


> if this is a new error I can't see it being a bent spindle without some major event occurring. My money is still on the chuck/backplate/spindle interfaces as the problem.



No major event, I'm with you on the diagnosis, that's where I'm going next.
I'm not near the lathe for a week or so, currently my shop is 50 miles from my house, that's living in LA!

"You mentioned you have ordered a ground bar, hopefully it has an MT taper you can fit directly to your spindle."

sadly no, its just  bar. Its a big spindle, manual says #5 morse taper. That would be a big bar! I guess I could get a morse taper reducer, MT5-MT4 for about $35 on amazon...


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## Anatol (Mar 22, 2019)

DJP said:


> I am curious if this lathe was purchased used.
> Is there a possibility that your lathe was dropped during transport?
> 
> Your only solution may be to shim the head stock to get it close enough.
> .



It was bought used but from a local hobbyist, never dropped afaik.  
But one can never be sure which is why I'm trying to be very methodical and measure and level everything in a logical order. 
"I'm sure that we would all like to see this issue resolved"
thanks for your kind thoughts, I'm working on it


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## goldstar31 (Mar 22, 2019)

Anatol said:


> thanks Norman, I know. This community is very knowledgable and generous.
> I have Schlesinger
> I was jut confused about your reference to 'mikes'



For mike read micrometer


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## Anatol (Mar 22, 2019)

petertha said:


> The 2 important surfaces that the camlock system registers to a corresponding mounted accessory on are the tapered cone (end of red arrow) and the rear face (end of green arrow). The nose front (orange arrow) doesn't contribute anything. Notice this back plate adapter is just a hole, it is not in contact with the lathe spindle. So when back plate & spindle are mounted together, cones coincide with one another and the faces are maybe 0.001" apart constant offset. Tightening the cams then bring the faces together. Ideally in a nice fitting arrangement the back plate has just a teeny bit of 'stick' &then pops off. Its a delicate fit.
> 
> So as pointed out ^above^ it matters not where you mount the DTI when checking the lathe as long as it is fixed. You are rotating the spindle & looking for deviation. For example if the spindle cone is not circular the DTI will wander in & out showing this deviation. Same thing with the nose flange face.



Again, thankyou for such a helpful and knowledgeable description, and the always helpful pics. 
So, if I understand correctly, the sides of the 'hole' in the backplate  (red arrow in second pic) are conical. I had not noted this. I now understand the cone sections function like a slice of morse taper. Tightening the camlocks brings the faces together, but the cones are doing the centering/alignment.  Makes brilliant sense. Thanks again.


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## Anatol (Mar 22, 2019)

goldstar31 said:


> For mike read micrometer


I know. What I was confuse about was how to use a mike in this particular test process. I did not see reference to using a mike in Schlesinger. He always shows DTIs. Are you suggesting using an inside mike for greater accuracy?


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## goldstar31 (Mar 22, 2019)

Anatol said:


> I know. What I was confuse about was how to use a mike in this particular test process. I did not see reference to using a mike in Schlesinger. He always shows DTIs. Are you suggesting using an inside mike for greater accuracy?



Instead of asking  all the time Schlesinger has such pretty pictures  showing how to set up tests.  Somewhat wryly, he's enough to get your job done-- once as he rightly says - Level  your machine FIRST.

'Nuff said?

N


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## Anatol (Mar 22, 2019)

goldstar31 said:


> 'Nuff said?
> 
> N



until I have something to report. Hopefully good news.


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## petertha (Mar 22, 2019)

Anatol said:


> Its a big spindle, manual says #5 morse taper. That would be a big bar! I guess I could get a morse taper reducer, MT5-MT4 for about $35 on amazon...



MT5 spindle is quite common for lathes like this. Same as my 14x40. You should get a reducer if one didn't come with your lathe, it gives you tooling options. This is what I was referring to when I said get a straight test bar with MT3 end. So in the head stock you insert the MT5/MT3 reducer sleeve, then the MT3 end of the test bar. Now you are accurately concentric & you can test spindle without any chucks or back plates involved. Likely you also have MT3 tailstock so the same test bar can be used there.

Is your test bar that you have coming accurately center drilled? That also adds additional functionality. Mind you you need a headstock center. So either you have an MT5 shank center (I'm guessing probably not likely) or you would be using an MT3 center in conjuction with aforementioned adapter sleeve.


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## cds4byu (Mar 23, 2019)

It seems to me that the first step is to establish the device that is causing the runout.

Put the bar in the chuck.  Use your dial indicator away from the chuck jaws (out along the bed where you have the larger runout).  Spin the bar and observe the runout.  Now mark the bar (using a sharpie) where the dial indicator is reading the maximum value.  You can tell which is the maximum value by lifting the indicator probe away from the bar and observing the direction of the needle.  

Now remove the bar from the chuck and rotate it 180 degrees so the mark you just made is on the opposite side from the dial indicator contact.  Check for runout again, and see where the maximum value on the indicator is.  If the maximum value is where the bar is marked, the runout is due to  the bar not being true.  If the maximum value is opposite the mark, the runout is due to something in the chuck/mounting system.

If the runout is in the chuck/mounting system, clean the mark off the bar, and check for runout.  This time, when you get the maximum reading on the indicator, mark the chuck and the D1-4 camlock ring to indicate the high side.  Now remove the chuck and rotate it relative to the spindle nose, then remount it.  Mount the bar back in the chuck, and do the test with the indicator. If the maximum reading is at the same location relative to the chuck, it's most likely a problem with the chuck and/or the chuck mounting plate.  If the maximum reading stays with the D1-4 ring, it's a probem with the spindle nose and/or the camlock system.

Since you've seen in on multiple chucks, I'm pretty sure it's something wrong with the spindle nose and/or the camlock system.  But in just a few minutes you should be able to confirm this 100%.

Carl


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## Anatol (Mar 23, 2019)

cds4byu said:


> It seems to me that the first step is to establish the device that is causing the runout.
> 
> Put the bar in the chuck.  Use your dial indicator away from the chuck jaws (out along the bed where you have the larger runout).  Spin the bar and observe the runout.  Now mark the bar (using a sharpie) where the dial indicator is reading the maximum value.  You can tell which is the maximum value by lifting the indicator probe away from the bar and observing the direction of the needle.
> 
> ...


thanks Carl, 
Advice understood. I've done all of what you suggest, but not quite as methodically. I'm away form the lathe but will get back to this and follow your advice ...on April fools day!


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## Anatol (Mar 23, 2019)

petertha said:


> Is your test bar that you have coming accurately center drilled? That also adds additional functionality. Mind you you need a headstock center. So either you have an MT5 shank center (I'm guessing probably not likely) or you would be using an MT3 center in conjuction with aforementioned adapter sleeve.



Just a raw bar. I can probably get it center drilled though, at a nearby precision shop. 
Headstock center...same as a tailstock center right? Fixed or live ?  - I've got both. But will need the adapter... Hang on, this is instead of a MT on the bar for the headstock end?  Thanks.


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## goldstar31 (Mar 23, 2019)

I don't think that you appreciate just how precise test equipment is required and 'clocking or miking' or whatever you call it demands simple but precise measuring equipment.  Somehow, I think that recommendations for cheaper and less accurate materials would have been suggested if they compared favourably


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## Anatol (Mar 23, 2019)

"I don't think that you appreciate just how precise test equipment is required"

I'm learning. 

The bar I have purchased and awaiting for is 
"1045 Precision Shaft Steel Round Bar 1" Dia x 12"Long 
Turned, Ground, Polished Precision Shafting Tolerance is (-.0005/-.002)"

not good enough?

"'clocking or miking'"

I don't know what that is


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## Cogsy (Mar 23, 2019)

Hi Anatol, I'm replying here so I don't clog up mcostello's similar alignment thread. In that thread you made the comment "*Its difficult (for me) to imagine a mechanical situation that would result in the bar drawing a cone where the point of the cone is at the outer end and the 'base' off the cone is in the chuck!*" and also "*Various folks have said it doesn't matter where you indicate from. But if the spindle and ways are not parallel in both planes, surely this would introduce an error?*" which leads me to believe you don't have a good handle on these types of errors yet.

Basically, mcostello's error is that his machine is cutting a taper. This means that if he puts a nicely round, straight bar in his lathe and puts a dial indicator on the saddle at some point down the bed his reading will be zero (or close to it) run out of the bar. However, when he machines the bar, the misalignment between the axis of rotation and the travel of the saddle means the diameter of the bar changes over distance. It means his depth of cut is increasing the further away he gets from the spindle and eventually it will cut to a point and make the bar into a cone. This means to measure his misalignment, a dial indicator needs to travel along a known (non-rotating) straight bar down the length of the lathe.

For your machine, as you have descried it at least, the bar is being held misaligned between the axis of rotation and the bar itself. This means, no matter where in space your indicator is placed at a stationary point, the bar will measure run out as the end 'wobbles'. The alignment between the bed and the axis of rotation is irrelevant to this measurement (effectively you could remove the headstock entirely and run it mounted in a vise and the same problem would remain). If you measured with an indicator mounted to the saddle as you traveled along the lathe with your bar not rotating, your reading would be dependent on the relative position your bar had ceased rotating and would tell you absolutely nothing about the problem. 

In simple terms, mcostello's spindle centreline is not pointed directly in line with the lathe bed/saddle travel, but your workpiece is not in line with the your spindle centreline. Very different things.


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## goldstar31 (Mar 23, 2019)

Your PGMS bar has no place in Schlesinger tests.   A couple of them would be delightful as the bed bars on a Quorn tool and cutter grinder. I hav e a pair on mine but that is not what we are about- is it?

Schlesinger uses a Morse taper to suit the internal taper of the specific spindle in. Sleeves simply add dimensional errors.

Again, Schlesinger specifies a minimum of TWO - do you call them dials for reading the deflection or what ever comes from very high precision centres.  The resolution of them is  possibly half a thous minimum and usually they have the indicator end changed to 'an elephant's foot' rather than a spring ball. Mine came from a Boxford tool and cutter grinder- and are more accurate.

Again, the levels are precision levels. 

In the case of a possible worn lathe, there are 'references 'of high precision.   I have a very decent cast iron surface plate, Johansson blocks which ring together, microscopes and so on.  It may look like a scrap yard but I have quality  stuff capable of measuring very accurately.

The sad thing is that I am getting very old and I have macular degeneration in both eyes- one 'wet' and the other 'dry' and even  reading and typing are now a real chore.

Time will soon come when all of it will go into the rubbish bin and in the meantime, I have to consider whether  I am continuing on my own projects. Trying to help others now is becoming increasingly nigh impossible.

You have the sources better than I can describe and in the circumstances  might I suggest that  you avail yourself of what is priceless information.

I wish you good fortune

Norman


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## Anatol (Mar 24, 2019)

Cogsy, Norman, dieselpilot, petertha and others: 

It is with respect, humility and gratitude that I thank you for your generosity with your knowledge and experience. I am not unaccomplished. I have achieved substantial things in several fields. I was remarking to a friend that learning the art of precision machining and really understanding the procedures, is one of the most challenging things I've ever attempted. I find two things especially interesting and important. 

That the trade/art/craft combines rigorous intellectual work - reasoning - with highly sophisticated and attuned  'sensorimotor' practices (what we used to call hand-eye coordination, manual dexterity, etc). 

That in cooperation with sophisticated tools and instruments, we can 'sense' minuscule variations beyond the ability of our senses. A DTI or a mike or a precision level is like a telescope or a microscope. But a telescope or a microscope only 'look', while with this machinery we also 'act'. 

 In our digital age, we are encouraged to think that abstract thought is all that is needed, because there are machines to do the 'work' - just press 'print'. In my opinion an entire generation, at least in the 'west', is being hoodwinked and deskilled. 

It seems to me this knowledge - the basis of the industrial revolution - is precious, and is disappearing rapidly. I hope to play a small role in preserving it. I'd also like to make some projects  Thankyou for your patience.


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## DJP (Mar 24, 2019)

My first home shop lathe was a 75 year old Soutbend with some wear. It drank oil and it required a slow approach to the final cut but for my needs it worked and provided value. I have since upgraded to a newer (still old) and tighter Myford but my approach to precision hasn't changed and I accept the limits worn into the machine. I'm sure that there are many levels of higher precision available to me if I upgrade.

My thoughts for your consideration are that perhaps this old lathe either needs to be rebuilt or used for less accurate work. Keep going in your quest but you may discover that running with tail stock or using a 4 jaw chuck are the only ways to minimize the errors due to wear and the best solution is a new machine. CNC and 3D printing require digital programming skills so that eventually our lathes and mills will be museum pieces. If you visit a small machine shop producing product you will see the future of our hobby. There may still be a rebuilt Southbend there for a specific job but the precision work is done by new digital machines in high volume.


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## goldstar31 (Mar 24, 2019)

In my perhaps warped view of things, it was partly recalling   a ridiculous offer of a tool and cutter grinder- which attracted no takers. The dedicated motor alone would have cost at least £100- the offer price for the whole thing. There were no takers!

Again when my turn comes, my children/my executors/ attorneys have been instructed to literally scrap my workshop rather than waste their precious lives in trying to find buyers who are prepared to put their hands into their wallets/pocket books to find realist prices. None of my stuff is  CNC or 3D printed. To put that onto the market would be even more of a fools errand.

Certainly in the UK, the closure of 'model shops' and such are an indication of what can only be an indication of wealth or the the willingness to pay a realistic price. Somewhat scurrilously, there is an ability to buy a phone for  £40 a month or £480 a year which is almost 5 times my teasing price of £100. I bought a virtually unworn SiegC4 for £350- delivered which was- and I'm an accountant( retired) a whole tenth of the new price.

For DJP's delectation, a slideways ground bed for a Myford Super7 was a mere £200 and my rather more rough and ready Blancharding was a mere £25 and - being somewhat of a accountant etc, I noted that both firms went into liquidation which is more or less a euphemism for 'Gone down the Swanee!'

What will happen when China is forced to put up its prices- I'm a political animal and able to play the Stockmarket- is anyone's guess but it will not be a benefit to the model engineer and his one off.

My thoughts- of course.

Norm


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## petertha (Mar 24, 2019)

Anatol said:


> The bar I have purchased and awaiting for is "1045 Precision Shaft Steel Round Bar 1" Dia x 12"Long
> Turned, Ground, Polished Precision Shafting Tolerance is (-.0005/-.002)"



Well....  
- It doesn't have centers on either end which means you cannot put it between centers as-is to dial in tail stock  at some point as an example. So somewhat reduced utility. 
- Its hardened so not exactly easy for a machine shop to do that job for you at reasonable $$ just as a guess. Now you have to be concerned how they are gripping it & center drilling it etc.
- Re tolerance, actually not that great but I guess relative to what you paid. Hard to know based on that info. Do they mean could be 0.9995" - .9980" anywhere along the shaft? Across one direction vs another on the same part of shaft? Compare to el-cheapo MT test bar from India below. The one I got tested favorably to the 10-thou mic in my arsenal FWIW. Any further testing I don't have capabilities myself.
- it doesn't have MT taper on end so cant be plugged into head or tail stock taper, so again a bit reduced utility. About all you can do in your issue is to chuck it & make measurements on that basis as already discussed. However you also just chuck the cylindrical portion of an MT ended test bar & accomplished the same thing.

https://www.ebay.ca/itm/3MT-Lathe-A...877671?hash=item3d2f053da7:g:ac4AAOSw8gVX2ZxK
Accuracy within 1 micron. Max.run-out :0.0001". Overall length :  335mm (13-3/16")


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