# 3 Jaw Chuck Jaw Alignment Issues



## Syn3rgy (Feb 26, 2013)

I have had some jaw alignment issues with the chuck that came with my HF 7x10 mini lathe from day 1, and I was hoping for an opinion on the matter from someone with more experience than myself. I noticed that no matter how carefully I chuck something it always seems to wobble. If I close the jaws all the way with nothing in them, its very easy to see that they don't all "meet in the middle". I would post a picture but I am not allowed to do that at the moment it seems. Two of the three jaws seem right, but one just doesn't seem to match. Now I have removed the chuck and jaws to verify they are in the correct position and when looking for the stamps with the numbers I noticed they are barely legible, I can only really make out a #1 on the chuck and the very bottom of the #2, the #3 is basically not even there, but the jaws where in the correct place according to what I can tell. I did try to switch the 2 & 3 just to make sure and then the jaws wont sync at all so I am 99% sure they are in the correct position. I did recently get a 4 jaw chuck from little machine shop and I am able to indicate in some drill rod to half a thousandth so I am fairly certain its just the 3 jaw chuck that's the issue. Could it be I just received a bum chuck (or set of jaws)? Can I just buy another set of jaws for this chuck or is that something that is specific to each chuck? 

Thanks


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## Ray C (Feb 26, 2013)

By how far off is this alignment issue?

Remove the jaws and look at the backs of them -where they engage the scroll.  You'll notice that each one has a different offset.  Align them in ascending order on the table.   Take the chuck and rotate the pinion until you see the leading/starting edge of the scroll through one of the jaw slots.  Back-up the pinion just a bit and insert the 1st jaw into the slot pressing down on the jaw while giving the pinion about 1/4 turn.  Feed the next two jaws the same way.   Once you've done that, you'll go from 99% sure to 100%.




Syn3rgy said:


> I have had some jaw alignment issues with the chuck that came with my HF 7x10 mini lathe from day 1, and I was hoping for an opinion on the matter from someone with more experience than myself. I noticed that no matter how carefully I chuck something it always seems to wobble. If I close the jaws all the way with nothing in them, its very easy to see that they don't all "meet in the middle". I would post a picture but I am not allowed to do that at the moment it seems. Two of the three jaws seem right, but one just doesn't seem to match. Now I have removed the chuck and jaws to verify they are in the correct position and when looking for the stamps with the numbers I noticed they are barely legible, I can only really make out a #1 on the chuck and the very bottom of the #2, the #3 is basically not even there, but the jaws where in the correct place according to what I can tell. I did try to switch the 2 & 3 just to make sure and then the jaws wont sync at all so I am 99% sure they are in the correct position. I did recently get a 4 jaw chuck from little machine shop and I am able to indicate in some drill rod to half a thousandth so I am fairly certain its just the 3 jaw chuck that's the issue. Could it be I just received a bum chuck (or set of jaws)? Can I just buy another set of jaws for this chuck or is that something that is specific to each chuck?
> 
> Thanks


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## Syn3rgy (Feb 26, 2013)

Thanks for the response and procedure. I actually did do what you said, and my 99% comment was really because I wasn't sure if I had them in the wrong place that would mean they would be way off, or just a bit like they are. I measured the gap with a feeler gauge and its about 18 thou off. I guess I can post pictures, so below you can see what I mean.

Thanks


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## Tony Wells (Feb 26, 2013)

Frankly, that is either a defective chuck, or someone has mixed a jaw from another chuck of the same make into it. Out of curiosity, can you chuck the ID of a bearing race or even a whole bearing if handy and see if the "other" side of the jaws has a similar issue? If not, then theoretically, you stand a chance of correcting this with a tool post grinder. If it has issues chucking ID's as well, then it's going to be a major bit of work, and I would be on the lookout for a new chuck if it were me.


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## Syn3rgy (Feb 26, 2013)

Mix up isn't possible, at least not here (only me, only one 3 jaw chuck), I guess they could have at the factory or something.

Upon closer inspection of the jaws I noticed that Jaw 3 looked a little off. As you can see from the picture it looks like it wasn't ground straight. Is this something I could realistically fix? Seems like its a might as well try scenario, probably would need to replace the chuck anyways unless someone has a better idea.


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## Tony Wells (Feb 26, 2013)

That may or may not be indicative of the specific problem. The serrations are machined before HT and then grinding. They're not precision by any means, so I wouldn't go strictly by them. But then, if the other jaws seemed to be consistent in that feature, it sure could be that there is a taper in the gripping surface. How they accomplished it I couldn't say, but as I mentioned, a TPG could be used to at least greatly improve on what you have. Some people are able to rig up a die grinder and touch up their jaws. It would be worth a try, at least.


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## Ray C (Feb 26, 2013)

OK, the picture clears things up...  Yeah, that chuck was made on a Monday or Friday I'd say.  Inspector #39 wasn't doing his/her job.

+1 on Tony's thought about checking "the other side" of the jaws to check for other geometric flaws.

You could try to fix it assuming there are no other geometry problems.  If it were mine, I'd do the angled sides in a surface grinder.  I can't tell if you have a circular contour in the center but that would be done with a rotary grinder.  I'd measure the angle of the other jaws and replicate that onto the flawed one.  Then I'd trim the "nose length" (for lack of a better term) so they all touch at the same time.  Jaws are pretty hard and milling would not be the ideal method of reshaping it.  It would eat coated HSS in 10 seconds and give carbide a run for it's money.  

Ray


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## iron man (Feb 26, 2013)

That really looks like a chuck with the jaws out of time mark each one with a felt tip marker and start in changing the slots they go into untill they all come out even mine are all numbered and if you dont put them in the right sequence in the same slot everytime you will end up with what you have. If not and it turns up just bad replace it or you can grind it. I have ground a few of them I take three pieces of key stock all the same size and insert them just shy of the three holding points you are going to grind tighten down the chuck till all three pieces of the keystock are tight. This gives the downward pressure needed for accurate grinding.

Now make a jig that will allow you to hold a dremal in your tool post pick a nice fine stone turn the chuck slow and the feed really slow till all three grind even. If the outside of the jaws need grinding you will need pressure on the outside of the jaws and grind the outside clean up the chuck and your lathe and you are done I can post some pictures of the setup if you want them. Ray


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## Syn3rgy (Feb 26, 2013)

Thanks for the info everyone. After some grinding, below is as close as I could get the jaws. I am sure now I will need to grid all three as described by Iron Man in order to actually get them accurate. @ iron man, if you could post some setup pictures that would be great, I am not quite sure I understand what your doing with the keystock. I do have a dremel, and various stones and diamond bits, I will just have to come up with something to hold it.

Thanks


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## twowheelinjim (Feb 26, 2013)

Harbor freight is great about accepting returns on issues like this. If you call them, they might even send you a replacement. I once purchased a bunch of tools online and a screwdriver set was missing one screw driver and one torx was deformed or not finish machined. They sent me a complete set and that was great. It's an avenue worth pursuing.


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## iron man (Feb 26, 2013)

Syn3rgy said:


> Thanks for the info everyone. After some grinding, below is as close as I could get the jaws. I am sure now I will need to grid all three as described by Iron Man in order to actually get them accurate. @ iron man, if you could post some setup pictures that would be great, I am not quite sure I understand what your doing with the keystock. I do have a dremel, and various stones and diamond bits, I will just have to come up with something to hold it.
> 
> Thanks
> 
> ...



I will set that up and take some pic's right now. be back in a while.. Ray


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## Ray C (Feb 26, 2013)

Looks a lot better!

I have seen (but never tried myself) where folks will take a rotary-type device like a drill that mounts on the toolpost.  They insert a grinding bit and move it into the small opening of the chuck jaws.  It grinds all three of them at the same time.  To do this, the rear/inner part of the jaws must be clamped down on something (preferrably something that is accurately round) to hold them in the proper position while being ground.  This is where things get tricky because when you clamp something back in the jaws, they to angle inward a bit.  

Hope that made sense -and again, I've not done this myself but gather many folks have.

Hopefully someone whose done this successfully can elaborate on the procedure.

Ray




Syn3rgy said:


> Thanks for the info everyone. After some grinding, below is as close as I could get the jaws. I am sure now I will need to grid all three as described by Iron Man in order to actually get them accurate. @ iron man, if you could post some setup pictures that would be great, I am not quite sure I understand what your doing with the keystock. I do have a dremel, and various stones and diamond bits, I will just have to come up with something to hold it.
> 
> Thanks
> 
> ...


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## iron man (Feb 26, 2013)

Here is one of the first simple dremal holders I made it worked real well. Ray


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## Tom Griffin (Feb 26, 2013)

The way to true up the jaws on a chuck is to bore a ring and grip it by the bore with the outside of the jaws. Then indicate the bore of the ring until it runs true. This will ensure that when the inside of the jaws are ground, they will be concentric with the outside of the jaws. This technique will also pre-load the jaws so they don't move while grinding and allows you to grind the entire length of the jaws in one set-up. Before any grinding is done on the jaws, indicate the outside of the chuck to be sure it is concentric with the spindle. And before doing any of this stuff, take it back to the store and tell them you want it replaced. If they sell junk like that, they should expect that some of it is going to get returned.

Tom


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## iron man (Feb 26, 2013)

Here is the keystock stuck in the jaws I left one out for the picture these are to long cut some no longer than the jaw. When you squeeze down on them this will put the correct pressure on the jaw You must pre-load the inside and the outside just like it is when it is being used just leave enough of the jaw exposed to grind this will allow you to grind the entire length of the jaw.. Ray


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## iron man (Feb 26, 2013)

Here is a little better shot to give you an idea on how to do it. TAKE your time have the chuck and your feed really slow and on your last few passes do not feed in anymore let it grind until there is no more to grind. This chuck was out abot 5 thousands after it was ground it come out perfect..I have used this setup on several chucks with all the same results and this is the simplest way to hold the jaws. To do the out side just put a hose clamp around the chuck and put some outward tension on the jaws then grind them.. Ray


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## iron man (Feb 26, 2013)

TomG said:


> The way to true up the jaws on a chuck is to bore a ring and grip it by the bore with the outside of the jaws. Then indicate the bore of the ring until it runs true. This will ensure that when the inside of the jaws are ground, they will be concentric with the outside of the jaws. This technique will also pre-load the jaws so they don't move while grinding and allows you to grind the entire length of the jaws in one set-up. Before any grinding is done on the jaws, indicate the outside of the chuck to be sure it is concentric with the spindle. And before doing any of this stuff, take it back to the store and tell them you want it replaced. If they sell junk like that, they should expect that some of it is going to get returned.
> 
> Tom



If you grip it from the outside of the jaws you will put outward pressure on the jaws which will pre load them in the wrong direction when doing an internal bore they must have pressure on them like they are clamping down on something like it would be used when you are going to turn something. The same goes for the outside of the jaws you must push out against something like a ring or hose clamp to put pressure on the jaws just as they would when your grabbing the inside of something they idea is to get the jaws to (tip) in the right direction under pressure. I have tried clamping onto a ring as you have described and the chuck was just as bad when I got done as when I started.. Ray


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## iron man (Feb 26, 2013)

Here is another way to do it or look at it just make sure the chuck clamps down on all three equally not two like what is pictured.. Ray


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## Tom Griffin (Feb 27, 2013)

iron man said:


> If you grip it from the outside of the jaws you will put outward pressure on the jaws which will pre load them in the wrong direction when doing an internal bore they must have pressure on them like they are clamping down on something like it would be used when you are going to turn something. The same goes for the outside of the jaws you must push out against something like a ring or hose clamp to put pressure on the jaws just as they would when your grabbing the inside of something they idea is to get the jaws to (tip) in the right direction under pressure. I have tried clamping onto a ring as you have described and the chuck was just as bad when I got done as when I started.. Ray



Ray,

The scroll is meant to work in both directions so it doesn't matter which way you pre-load the jaws. The important thing is to keep the inside and outside concentric. Otherwise the chuck may work well clamping on the inside of the jaws but will run out when using the outside. If you had trouble doing it this way, the scroll in your chuck was probably worn out.

Tom


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## Syn3rgy (Feb 27, 2013)

The newbie is confused, should I be trying the ring or key stock method? @iron man thanks for the pictures by the way I now understand what you were describing.

I did indeed try to call HF to see about a replacement but ended up having to leave a message and they have yet to call back. I'll try again tomorrow, but I figured it might be a good thing to learn about anyways, and I couldn't make it any more useless than it already was.


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## Tom Griffin (Feb 27, 2013)

Since your chuck is new there won't be any wear in the scroll, so either method will work. Just be sure to indicate the outer gripping surfaces of the jaws before you do anything to the inner ones. They both must be concentric when you are done.

Tom


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## iron man (Feb 27, 2013)

TomG said:


> Ray,
> 
> The scroll is meant to work in both directions so it doesn't matter which way you pre-load the jaws. The important thing is to keep the inside and outside concentric. Otherwise the chuck may work well clamping on the inside of the jaws but will run out when using the outside. If you had trouble doing it this way, the scroll in your chuck was probably worn out.
> 
> Tom



Tom my chuck was brand new it does not matter the force of the jaws cause them to tip or tweak slightly causing run out you are also running on the opposite side of the scroll you have to pre load in each direction and grind in each direction just as you would if you where holding an object I have done this many many times I worked in a machine shop for 25+ years and this is how I was taught by old German master who rebuilt lathes , Mills ,ect all of his life he would do this to new expensive chucks to cure run out as well...And these cheap chucks have a little play in them and in the scroll so it does matter.. Ray

 Just Google ( The proper way to grind a lathe chuck ) and you will see more examples of what I have showed you other methods maybe easyier but they all hold down the same..


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## Syn3rgy (Feb 27, 2013)

:winner:key stock, I do believe I have some around already so I will give it try today. Thanks again, I'll post the results later.


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## Syn3rgy (Feb 27, 2013)

It's done, and seems to have worked just fine. The first thing I chucked after grinding went in much nicer, I didn't feel like I had to crank down just to get it tight, and all the jaws grabbed at the same time. I guess I will see how it goes on the next project. Thanks again everyone!


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## AR1911 (Feb 27, 2013)

I have never seen the keystock angle - I like that a lot.

I may have to do that on the new 6" Shars with .008" runout


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## iron man (Feb 28, 2013)

Nice little mount for your dremal glad it worked out.. Ray


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## Kernbigo (Feb 24, 2014)

I  use square gage blocks instead o f key stock more precise


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## Moper361 (May 31, 2019)

A lot off good info in this thread .as i have a 4 jaw indipendent chuch that does obviously have this issue but has an issue off extreme tapper on the clamping faces so when round bar is clamped in it the front of the jaws clamp tight but the back end off the jaw is not tight slight gap .i was thinking off using a ring as suggested in this post on the outside clampping surface and zero it in center then grind the jaws internally .Any thoughts on this method and open to suggestions


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## Latinrascalrg1 (May 31, 2019)

Moper361 said:


> A lot off good info in this thread .as i have a 4 jaw indipendent chuch that does obviously have this issue but has an issue off extreme tapper on the clamping faces so when round bar is clamped in it the front of the jaws clamp tight but the back end off the jaw is not tight slight gap .i was thinking off using a ring as suggested in this post on the outside clampping surface and zero it in center then grind the jaws internally .Any thoughts on this method and open to suggestions



I personally haven't completed the process myself but have read enough to learn that if you intend to square up the "Inside" jaws you would need to apply an inside the jaws jig and apply closing pressure!  
   By placing a ring around the OUTSIDE portion of the jaws and then applying tension by OPENING the jaws (by turning chuck key in counterclockwise direction)  you apply pressure in the wrong direction for the intended preferred outcome.  If you then proceed to grind the Inside Jaws you will definitely st rhe very least end up being in the same boat but realistically speaking the chances are your boat now has a big hole in the hull! 
So to Keep it simple,  you need to clamp a jig of some sort that is correctly setup dimensionally so that you tension the jaws into the grinding 
stone NOT Away from it! Basically speaking,  placing the ring on the outside jaws is how you setup for grinding the outside jaws.

Hope this was helpful...... please update the thread with your results and the process you decide on using


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## Moper361 (May 31, 2019)

O





Latinrascalrg1 said:


> I personally haven't completed the process myself but have read enough to learn that if you intend to square up the "Inside" jaws you would need to apply an inside the jaws jig and apply closing pressure!
> By placing a ring around the OUTSIDE portion of the jaws and then applying tension by OPENING the jaws (by turning chuck key in counterclockwise direction)  you apply pressure in the wrong direction for the intended preferred outcome.  If you then proceed to grind the Inside Jaws you will definitely st rhe very least end up being in the same boat but realistically speaking the chances are your boat now has a big hole in the hull!
> So to Keep it simple,  you need to clamp a jig of some sort that is correctly setup dimensionally so that you tension the jaws into the grinding
> stone NOT Away from it! Basically speaking,  placing the ring on the outside jaws is how you setup for grinding the outside jaws.
> ...


Yes can see what your saying and can understand this on a 3 jaw self centering chuck .i have the issue with independant chuck .the issue is not as described in initial thread but different type of issue off the clamping faces being tapered IE the tip off the jaws clamping the work while the rear of the jaws not touching .So my thoughts are if i was to put a ring on the outside off jaws and at the tip off the jaw this would hold the jaws at the front in tighter and when ground possibly may end up about right .


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## jcp (May 31, 2019)

This is the jig I used.....




__





						Chuck Jaw Truing Fixture
					





					lathe.com


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## Moper361 (May 31, 2019)

jcp said:


> This is the jig I used.....
> 
> 
> 
> ...


That puts a good perspective on it. I could get a plate water jetted out that would severve that purpose even on a 4 jaw independent chuck this method would work .you would just have to keep working the jaws around taking readings of the outside of the jaws untill centered and then grind internally. Thanks for that JCP


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## Moper361 (May 31, 2019)

One more question on my mind is what would be a suitable stone to use in my die grinder to grind the jaws .i have two electric die grinders 1 with a 1/8 size chuck and another with 1/4 inch chuck i was thinking of utalizing the larger grinder ?


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## jcp (May 31, 2019)

I would think larger would be better.


Sent from my iPhone using Tapatalk


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