# 4 Jaw Independant Issue



## slingshot (Mar 5, 2015)

I have finally got my lathe down to .002 taper in 7'' after leveling up the ways with a precision level. Now i need to move the headstock (which is adjustable) pm 12x36 to correct the taper.

Before I do that i really need to use my independent four jaw but i am having a issue with it.I used to stick a piece of known good stock in it 7'' out put a di on it toward the T/S end get it true run the di to the chuck end dead on. Now I have two independent 4 jaws with the same back plate for both.My old 4 jaw i can put a di on a known good piece and it has .120 run out.

Now I just got my new independent 4 jaw same as the old one boted it up put a 7'' piece of stock run the di to the t/s true it up run it to the chuck and have .030 run out/can someone tell me what is going on here.the back plate is running true


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## Ulma Doctor (Mar 5, 2015)

you might think twice about moving the headstock unless you are positive that it's going to give you the desired result.
your jaws may be ever so slightly out of square compounded by a shaft that might not be 100% straight at 7" too.
you may want to try an experiment,
center drill the rod and mount between centers, (a drive dog is not necessary , you are only checking alignment)
and give a run down the shaft with the indicator and see if there is an issue there.
if your alignment checks out between centers, you'll know for sure it's not Headstock to Tailstock alignment.
you'll have more info at that point to make further determinations.


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## JimDawson (Mar 5, 2015)

+1 what Ulma Doctor said.  You might also take a look here http://www.hobby-machinist.com/threads/4-jaw-accuracy.32474/#post-274453


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## slingshot (Mar 6, 2015)

Ulma Doctor said:


> you might think twice about moving the headstock unless you are positive that it's going to give you the desired result.
> your jaws may be ever so slightly out of square compounded by a shaft that might not be 100% straight at 7" too.
> you may want to try an experiment,
> center drill the rod and mount between centers, (a drive dog is not necessary , you are only checking alignment)
> ...




Just wanted to say it is a test bar that i am using and i am not interested in tailstock alignment at this point


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## itsme_Bernie (Mar 6, 2015)

You really have to check things on your lathe in a certain order.  

Like UlmaDoctor said, your jaws may be ground funny and then holding the workpiece out skew.   

Once you start moving the headstock around, you are getting into a realm of machine tool alignment that you need special tools or experience to be able to easily reverse if you are wrong.  I am pretty sure, with patience, a home shop guy can do it, but it takes a lot of patience!  Much more than aligning a tailstock!  

I know you aren't interested in the tailstock right now, but I am quite sure it has to come first.  

Many people grind out their lathe chuck jaws with a Dremel attached to the Toolpost, driven by the carriage.  Anyone think this is a bad idea for his next step?

Bernie 


Sent from my iPad using Tapatalk


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## John Hasler (Mar 6, 2015)

itsme_Bernie said:


> You really have to check things on your lathe in a certain order.
> 
> Like UlmaDoctor said, your jaws may be ground funny and then holding the workpiece out skew.
> 
> ...


I'd want to check the alignment  with a test bar in a collet.


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## slingshot (Mar 6, 2015)

John Hasler said:


> I'd want to check the alignment  with a test bar in a collet.


I have been around and worked in machine shops all my life just not with lathes .I have a precision level and have the ways perfect i have .002 taper I have tried twisting the ways to get the taper out but no change. so i am pretty sure the headstock needs moving.But right now i am more concerned with the 4 jaw chuck i can't fig out what is going on with this thing


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## JimDawson (Mar 6, 2015)

It really sounds like the jaw centerline is not perpendicular to the chuck back.  I had the same problem on a cheap 4-jaw and fixed it by chucking up on a shaft, and machining the back of the chuck to the jaws.


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## Ulma Doctor (Mar 6, 2015)

slingshot said:


> Just wanted to say it is a test bar that i am using and i am not interested in tailstock alignment at this point



Taking this extra step will save you a lot of headaches later on, but you are free to do as you wish.
good luck


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## stupoty (Mar 6, 2015)

John Hasler said:


> I'd want to check the alignment  with a test bar in a collet.



That will be an easy way to check the alignment before the head comes off.

And handy if you do want to adjust the head as you would probably need a test bar in whilst you were adjusting.

Stuart


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## slingshot (Mar 6, 2015)

stupoty said:


> That will be an easy way to check the alignment before the head comes off.
> 
> And handy if you do want to adjust the head as you would probably need a test bar in whilst you were adjusting.
> 
> Stuart




Thanks guys,
I have got the lathe cutting true 0 taper t/s lined up and 0 taper facing a 6'' plate. So it is good both ways now if i could get this 4 jaw straightened out i would be jam up jelly tight.


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## tmarks11 (Mar 6, 2015)

slingshot said:


> I have got the lathe cutting true 0 taper t/s lined up and 0 taper facing a 6'' plate


You end up aligning the headstock, or did you just do some additional leveling of the base or the bed?

Regardless, nice job.


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## slingshot (Mar 7, 2015)

tmarks11 said:


> You end up aligning the headstock, or did you just do some additional leveling of the base or the bed?
> 
> Regardless, nice job.





I ended up having to move the head stock because it was off both ways, cross slide to spindle and ways to spindle.


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## slingshot (Mar 7, 2015)

Hey anybody need a heavy boat anchor? LOL i am very frustrated with this four jaw I really need it to do some tight tolerance work.I did go ahead and true up the back plate.I can't get a piece to run no better than .030.

I did notice a couple of things i can zero indicate the piece at the chuck run the di down the part and have .0 rotate 60 degrees and its off can't remember how much.so it's like two chucks opposite hold true and the others don't so i still got some work to do.rotating chucks jaws ect.

I wonder if vertical alinement could be giving me some trouble but the three jaw runs fine. does anybody have a clue


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## JimDawson (Mar 7, 2015)

This fixed mine.  Still need to grind jaws true. but it works.  I reposted my thread that got lost.  The real key is squaring up the back with the jaws.

http://www.hobby-machinist.com/threads/asian-4-jaw-chuck-adventures-re-post.33311/


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## slingshot (Mar 7, 2015)

Thanks that was very informative.
My 4 jaw has the four bolt type through the face and the back of the chuck only hits the outside of the back plate Where the bolts go through on the back is recessed and there is probably 1/4'' gap between the plate and chuck body.I don't think that would be a issue.Looks like i am going to have to start rebuilding my new chuck or start looking for a buck or bison.


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## Bill C. (Mar 7, 2015)

Okay sounds like you are making progress.  I assume the jaws are bolted on their holders, you have removed and cleaned or deburred the mating surfaces just to be sure.   I hope you get it running true soon.

I used some really old used four jaw chucks in my time.    And a couple 3 jaw chucks that should have been recycled.  

Good luck and a successful outcome,


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## slingshot (Mar 10, 2015)

Hey i was wondering if anyone here has a independent 4 jaw with direct D-1-4 ?

I found one on ebay for a fair price I had to send the cheap Chinese chuck back,the body was out with the jaws


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## JimDawson (Mar 10, 2015)

A word of warning on any direct mount chuck.  If it doesn't run true it is a real PITA to get it straightened out.


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## 18w (Mar 11, 2015)

Two of my chucks, a 3 jaw and a 4 jaw are direct mount. They are accurate and no problem. I wouldn't buy a cheap or unknown brand with a direct mount though. Actually I would never again buy a cheap or suspect quality chuck. Life is too darn short to put up with stuff like that. Jim is right, not a easy fix if it is out of tolerance.

Darrell


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## atunguyd (Mar 11, 2015)

Slingshot, I recently went thorough the same issues with a new 4jaw. I did the following tests :

1. Remove all the jaws and run a DI on the face of the chuck to confirm that the chuck is running in axial alignment with the headstock, also do this on the side of the chuck to verify radial alignment.  Do the above for each bolt position on the chuck (normally 4) and note which gives you the best results. Give axial alignment priority as you can dial out radial with the jaws when working. 

2. Once you have the chuck body aligned move onto the jaws. Replace them and Mount a test bar, dial it in near the headstock the run your dial indicator out to about 6" and check runout note how much runout and in what position the high point is relative to the jaws.  Now remove the jaw where the high point was ands swop it with the jaw opposite it.  Again chuck up your test bar and perform the same test. If the high point moved with the jaws you can be certain that the error is with your jaws and not the headstock.  For me this was the case.  You can resolve this by grinding your jaws.  However what I did first was to make up a list of every permutation of jaw to slot (24 combinations, hint label the jaws and slots) and perform the above test with each combination noting the resulting runout at 6". I found a best case of 0.06mm at 100mm (I work in metric) which I ended up using and did not need to grind my jaws.


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## Rich V (Mar 11, 2015)

If you had a chuck that was out of axial alignment do to the jaws not being true could one chuck it onto a precision bar mounted between centers then true up the back mounting surface to make it run true? Seems that would get everything properly aligned?


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## JimDawson (Mar 11, 2015)

Rich V said:


> If you had a chuck that was out of axial alignment do to the jaws not being true could one chuck it onto a precision bar mounted between centers then true up the back mounting surface to make it run true? Seems that would get everything properly aligned?



You are absolutely correct!

http://www.hobby-machinist.com/threads/asian-4-jaw-chuck-adventures-re-post.33311/


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## slingshot (Mar 12, 2015)

Hey guys I am looking for a good 8''4 jaw chuck I stumbled upon this chuck on ebay and wanted to see what you think?Because i don't believe this is a bison chuck  the box next to it has a number on it that is a 8'' general.It has a bison sticker on it but i don't think it's a bison opinions pls.

http://www.ebay.com/itm/BISON-LATHE...622?pt=LH_DefaultDomain_0&hash=item4d2e46d07e


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## benmychree (Mar 12, 2015)

slingshot said:


> I have been around and worked in machine shops all my life just not with lathes .I have a precision level and have the ways perfect i have .002 taper I have tried twisting the ways to get the taper out but no change. so i am pretty sure the headstock needs moving.But right now i am more concerned with the 4 jaw chuck i can't fig out what is going on with this thing


The headstock thing is easy if you have at least one vee way; just slip in a shim in between the headstock and one vee way surface at opposite sides on each end, thus pivoting the headstock one way or the other.  The best way, of course is scraping the surfaces of the headstock to achieve a like result, but for minor corrections, this method works well, I have done it on several lathes that I have owned.


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## bvd1940 (Mar 12, 2015)

slingshot said:


> I have been around and worked in machine shops all my life just not with lathes .I have a precision level and have the ways perfect i have .002 taper I have tried twisting the ways to get the taper out but no change. so i am pretty sure the headstock needs moving.But right now i am more concerned with the 4 jaw chuck i can't fig out what is going on with this thing




I ran into the same problem after the move to the new shop and I have a PM 1440 B and I had to re aline my head stock and it involves 4 hold down bolts and jack screws with a bit of testing as you go.
Just be methodical and write your steps and movement amount as you go.
Its not that hard just have patience.
just my 2 cents worth


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## barrydc1 (Mar 12, 2015)

If you ever have issues with your headstock again (or if you didn't do things properly) you really need to review this thread between myself and Richard King who rebuilds lathes and machinery.  He helped me immensely and this thread article is the summary of that help. http://www.hobby-machinist.com/thre...he-tailstock-with-headstock.13710/#post106737


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## slingshot (Mar 13, 2015)

Hey Guys has anyone looked @ this chuck? I will buy it if it is a bison but i don't think it is.
http://www.ebay.com/itm/BISON-LATHE...622?pt=LH_DefaultDomain_0&hash=item4d2e46d07e


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## tmarks11 (Mar 13, 2015)

It must be a real Bison... it has the right sticker/badge right there! /s

except...

It is suspicious is that it is sitting next to a cardboard box labelled "271-6010", which is Enco's part number for their Interstate cheap ($112) Chinese chuck:

http://www.use-enco.com/1/1/32555-i...ur-jaw-independent-lathe-chucks-271-6010.html

Also... the chuck in the ebay add doesn't have "MADE IN POLAND" stamped into the face like the Bison ones do, or any Bison part numbers stamped on it.

Also... the "Bison badge" is not set into a shallow depression, but just glued to the face of the chuck.  All the Bison I have seen (and owned) have the badge inset so it is flush.

Also... no oil port on the chuck, unlike the Bison chucks.

Also, that small depression on the opposite side from the Bison chuck, that is in line with the bolt hole?  In the Enco catalog, they show that the interstate badge is glued into that hole...

Makes me suspicious that someone is financing their upgrade to a Bison by peeling the Bison badge off and sticking it on the chuck they are replacing.

I definitely would not buy it.


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## slingshot (Mar 13, 2015)

Thanks Tmark that is exactly what i was asking, and yes i seen the same things you are talking about. I question the seller and he said it was just a box he had laying around! not lol
This is not a bison chuck that is for sure. thanks


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## tmarks11 (Mar 13, 2015)

slingshot said:


> I question the seller and he said it was just a box he had laying around! not lol



"Just a box lying around" that happened to hold a chuck exactly the same as the model he is claiming is a Bison?  What a chump. The giveaway is the recess where the interstate logo used to be.

I am assuming that he picked it up in a lot sale, since is a high-volume seller, so maybe he doesn't actually know any better.


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