# Do I Need To Resurface The Back Of My Chuck



## Swerdk (Sep 29, 2015)

￼regarding test indicator
1 div= .0005

I set the test indicator zero, this is the worst I get when I tested the spindle portion of chuck 00020
	

		
			
		

		
	









	

		
			
		

		
	
 ( 4 divisions)that is supposed to say twenty ten thousandth. 

	◦	did I read that right?

	◦	My three  jaw Chuck on the other hand  is off by 14 divisions  with a .0005 test indicator. 

does that mean I need to clean up back of 3 jaw?  
￼

	◦	Does it really matter?  that is the question
 I don't need more work but if it's going to skew my work I will do it.  
	◦	math question is .0005 x 14 divisions = 0.007 ?




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## Andre (Sep 29, 2015)

In the first picture, if that's how you took your measurement you need to re-measure it. When you are using a test indicator the needle has to be as parallel to the surface as possible, not perpendicular. Or you get a false reading. Some pics for reference (not mine).

http://i.ytimg.com/vi/jz9dWUUxibE/hqdefault.jpg

http://itdc.lbcc.edu/oer/machineTool/precisionTools/precisionToolsALT/images/dial2.jpg



> My three jaw Chuck is off by 14 divisions with a .0005 test indicator.



14 divisions of a half thousandths indicator (supposing every division is a half thou) means the chuck is off by .007". Acceptable for most 3 jaw work.



> How many .001 = .0005



.0005" is half of .001".


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## Swerdk (Sep 29, 2015)

Your to quick i just cleaned up post. I did not know that about test indicator placement though


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## Swerdk (Sep 29, 2015)

I will remeasure


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## John Hasler (Sep 29, 2015)

Looks like you are measuring the face of your spindle, not the back of the chuck.  Is that a registration surface?  If not it doean't matter.

Andre is right about the technique.


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## Swerdk (Sep 29, 2015)

I measured the face of my spindle then the face of the chuck to see the difference. I figure if there is a difference then it must be the back of the chuck causing it?


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## Swerdk (Sep 29, 2015)

I wish i could work in garage as much as i am chained to a county desk for another 10 years


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## eeler1 (Sep 29, 2015)

Check chuck runout. Mark your posts and locks where the least runout occurs.  Always mount it in the same location.  

If you still have a problem, then start looking at other suspects.


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## John Hasler (Sep 29, 2015)

Install the chuck on the lathe and measure the axial runout on the face of the chuck.  Then chuck up a piece of precision rod (1" or so) and measure the radial runout of the rod near the chuck.  Those are the numbers that matter.


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## Swerdk (Sep 29, 2015)

Axial runout? Thats the face of the chuck correct?


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## Swerdk (Sep 29, 2015)

Googled it nevermind


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## John Hasler (Sep 29, 2015)

Swerdk said:


> Axial runout? Thats the face of the chuck correct?
> 
> 
> Sent from my iPhone using Tapatalk


Correct.


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## middle.road (Sep 29, 2015)

Also just for kicks, if you have a second indicator, double check it.


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## Chipper5783 (Sep 29, 2015)

I would be extremely cautious to cut the face of the spindle:


It is a critical reference and the manufacturer would have tried to get it right


Moving that face back a small amount will have a major effect on the position on the taper (both the taper and the face contact at the same time)


That should be a pretty hard surface


It is not necessary to touch the face of the spindle for getting a chuck to run its’ best – that is what a mounting plate is for.


Chuck mounting / tuning is a very worthwhile exercise (and has been covered on numerous posts on all the usual machinist forums).


You are onto a good topic.  It is no surprise that a chuck right out of the box, mounted onto the spindle is not that great.  There are a number of approaches one can take (and many opinions), here is what I have done (with credit to numerous folks much smarter than me)


My recollection is that a lot of dialing/measuring was involved, and:


FIRST and #1, Mount up just the adapter plate and get it sitting properly on the D1 mount.  It should pull right up snug against that flat face (no gap at all), and it should be snug on the taper (some of my chucks I have to bump with the palm of my hand to get them loose).  If you have to bump the chuck with a block of wood, then open up the taper of the adapter plate(VERY SLIGHTLY – a small amount will move it back a lot) by hand working the taper in the lathe (generally need a second chuck or better yet, a second lathe).  This can take several iterations.


Once that is done, mount just the adapter plate and mark the position


Take a facing cut on the adapter plate. The point here is that even if the face of the spindle is out of whack, the face of the adapter plate will be correct.


Install the chuck on the adapter plate and see what you have (chuck up a nice smooth bar, measure radial runout near the jaws and several inches out).  This will evaluate radial runout and angular alignment.


Decide what to do next, depending on what you want and how well it is working.


If the angular alignment is not too good (I assume you have gone through the whole lathe leveling thing), then you would probably skim the back face of the chuck body (again, you need another chuck – preferably a bigger one, chuck up a good sized bar, take a skim cut on the bar to true it, grip the bar with the chuck you are tuning so you can skim the back face.) put it all back together and check again.


To address a radial runout, you can undersize the register on the adapter plate, then install the chuck body with the bolts only snug, then with a piece of smooth bar in the chuck, bump the chuck around until the bar runs true, then fully tighten the body bolts (sort of your own set true chuck).



At every step, measure at least 3x before you cut.




The adapter plate is the component that is designed to accept the adjustments.  A little skim on the chuck body is not a major sin (simple and easy to do).  Cutting the spindle mount? – I’d be extremely reluctant unless there was a very obvious issue and I could not figure out another way to solve that issue.

Let us know what you find out.
Regards, David


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## Chipper5783 (Sep 29, 2015)

Oh, and now seeing the title of your OP "Do I Need To Resurface The Back Of My Chuck?"  - You picture is of the back of the adapter plate.  No, you do not need to resurface the back of the chuck adapter plate (taking even a small amount off that back surface will dramatically effect the mounting taper - which you could also re-cut, but it is a lot of work to get right and is not necessary if the goal is to tune up the chuck).


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## T Bredehoft (Sep 29, 2015)

Lets have a reading with the stem of the indicator parallel the face it's measuring, before we continue the discussion on what to modify.


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## JimDawson (Sep 30, 2015)

In addition to the above, you might want to review these two posts,

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

http://www.hobby-machinist.com/threads/rant-5c-collets-chuck-d1-4-cam-lock.23838/#post211256  The real work starts on page 2 of this thread, but read through the whole thread.

Both threads show the use of both types of indicators.


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## Swerdk (Oct 3, 2015)

What am I doing wrong I am trying to remove the adapter plate from the chuck yes I removed all the bolts this plate will not budge is there some kind of trick to this I think somebody super glued it in China
	

		
			
		

		
	







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## Rich V (Oct 3, 2015)

Swerdk said:


> What am I doing wrong I am trying to remove the adapter plate from the chuck yes I removed all the bolts this plate will not budge is there some kind of trick to this I think somebody super glued it in China
> 
> 
> 
> ...


Did you try tapping it with a brass/lead hammer? Light tapping around the perimeter can knock it lose. I have also used a razor blade in the seam as a wedge to get it started.


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## Swerdk (Oct 3, 2015)

I will try again grrrrrrrr


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## Swerdk (Oct 3, 2015)

Second question when you take the jaws off of your three jaw chuck how do you get them on so that they all are equal you think you put them on at the same time and make sure they all grab at the same time but every time I've done it it's not equal what am I doing wrong I do see there is a one two and three on the jaws and I made sure that they're going into the correct slots


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## Swerdk (Oct 3, 2015)

OK never mind I saw the second question with the jaws I lined them up with the grooves what a pain back to the first question to the gentleman that told me about razor blades thank you so so so much it worked now to my next task


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## JimDawson (Oct 3, 2015)

You have three threaded holes in the back plate.  Try screwing the bolts into those, I am assuming they are tapped through for jack screws.  It should come right off.  Work your way around them, and don't try to do it all with one bolt.


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## Swerdk (Oct 3, 2015)

That's also sounds like a good idea but the razor blades work perfectly
I just wanted to give an update to everyone that was helping me decide if I needed to resurface my adapter plate and or my chuck. It turns out after I remeasured the proper way I found everything still off so I then started to take everything apart without knowing how to put it back together. UGH! One and a half hours later. I realized my only problem was that I was not seating the chuck properly to the lathe and once I seated it correctly my run out was minimum under 2 thousandth  on the adapter plate and shy of 2.5 on the test bar. YEAH 



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