# Tight 3 Jaw Chuck



## lpeedin (May 5, 2016)

Since day 1 the 3 jaw Chuck on my 1127 has been very tight in regards to running the jaws in & out. I attributed this to it being new, but it's not got any better. I've removed the jaws several times looking for burrs, swarf, whatever that might be the cause. It really is a task to run the jaws in & out and with my old arthritic hands I often have to use both hands. I removed the jaws again today & finally discovered what I think might be the issue, but before I start filing, grinding, contacting Matt, or any other remedy, I'd love some opinions from others who have similar equipment. 

Note in the picture below that each of the 4 valleys has a relief except the one in the upper left. All 3 of the inside jaws are like this; however, all 4 of the valleys on all 3 of the outside jaws are relieved. All 4 of the valleys on each of the 4 jaw Chuck jaws are also relieved. 

It's the same valley on each of the inside jaws - like maybe a step was forgot on the set of jaws. 






Would really appreciate if some of you would check your jaws and see if yours are the same. You can tell without removing the jaws from the Chuck as shown in this pic. Note the unrelieved valley is in the lower left. 






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## stevemetsch (May 5, 2016)

Do the outside jaws work better??? If so you have your answer.
Steve


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## lpeedin (May 5, 2016)

stevemetsch said:


> Do the outside jaws work better??? If so you have your answer.
> Steve


 Yes, they work much better.


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## Bob Korves (May 5, 2016)

If it is still in warranty, get the chuck replaced.  If not, use a cutoff wheel in a die grinder and make your own reliefs.  Even a hacksaw with a round grit blade might work.  It can be a low tech job, any amount of relief is acceptable, it does not need to be as much as you see on your jaws.

The corner across the jaw from it also does not look like it is properly relieved, on one face yes, on the other no, from what I can see in the pics.


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## Ulma Doctor (May 5, 2016)

i'll bet you that if you were to stone the mating lands of the jaw, you could reduce the friction between the jaw and the chuck


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## lpeedin (May 6, 2016)

Bob Korves said:


> If it is still in warranty, get the chuck replaced.  If not, use a cutoff wheel in a die grinder and make your own reliefs.  Even a hacksaw with a round grit blade might work.  It can be a low tech job, any amount of relief is acceptable, it does not need to be as much as you see on your jaws.
> 
> The corner across the jaw from it also does not look like it is properly relieved, on one face yes, on the other no, from what I can see in the pics.



Thanks, but as I stated in my OP, I wanted to hear from others with similar equipment before grinding or contacting Matt.


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## Bob Korves (May 6, 2016)

lpeedin said:


> Thanks, but as I stated in my OP, I wanted to hear from others with similar equipment before grinding or contacting Matt.


A chuck is a chuck, they have been making them about the same for 100 years or more.  One of the reasons import lathes are so much cheaper is that quality control is pretty much left up to the buyers and the dealers.  I know, because I have one, too.  Your problem is pretty much obvious from the photos.  See what Matt will do for you, if damage control makes up for lack of initial quality.  I suspect strongly that Matt will work with you if the lathe is still in warranty.  I just wanted you to know that you can repair it yourself without major expense and effort if it comes to that.  Replacement jaws are not a good idea, they are hand fitted and serialized to the chuck.


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## sanddan (May 6, 2016)

Rat (her than the hassle of return shipping and such I'd just relieve the corners with a die grinder using a thin cutoff wheel (I have that tool so that influences my comment). It depends on what tools you have available, a file would also work and be more controllable. See Oxtool the file king


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## chips&more (May 6, 2016)

Yes, maybe a corner is rubbing. But you said nothing about measuring the clearances? And clearances compared to the working jaws. If you confront Matt without that clearance info you will not be in the best position to make an argument…Dave.


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## tq60 (May 6, 2016)

A micro file in round shape (think chainsaw file but one from those pocket kits) with lots of oil or paint thinner.

Make a wood block that fits in the groove then notch to hold the file.

But first check with vendor.

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## FLguy (May 7, 2016)

lpeedin said:


> Since day 1 the 3 jaw Chuck on my 1127 has been very tight in regards to running the jaws in & out. I attributed this to it being new, but it's not got any better. I've removed the jaws several times looking for burrs, swarf, whatever that might be the cause. It really is a task to run the jaws in & out and with my old arthritic hands I often have to use both hands. I removed the jaws again today & finally discovered what I think might be the issue, but before I start filing, grinding, contacting Matt, or any other remedy, I'd love some opinions from others who have similar equipment.
> 
> Note in the picture below that each of the 4 valleys has a relief except the one in the upper left. All 3 of the inside jaws are like this; however, all 4 of the valleys on all 3 of the outside jaws are relieved. All 4 of the valleys on each of the 4 jaw Chuck jaws are also relieved.
> 
> ...


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## FLguy (May 7, 2016)

I have the same lathe and yes the 3 jaw chuck is very tight and the 4 jaw is fine. I thought of using some 140,000 grit diamond powder to smooth things out a bit but haven't yet.


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## lpeedin (May 7, 2016)

FLguy said:


> I have the same lathe and yes the 3 jaw chuck is very tight and the 4 jaw is fine. I thought of using some 140,000 grit diamond powder to smooth things out a bit but haven't yet.



Thanks for the response.


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## Bob Korves (May 7, 2016)

sanddan said:


> Rat (her than the hassle of return shipping and such I'd just relieve the corners with a die grinder using a thin cutoff wheel (I have that tool so that influences my comment). It depends on what tools you have available, a file would also work and be more controllable. See Oxtool the file king


The jaws should be hardened.  A file might just skate on them.  But it is worth a try...


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## qualitymachinetools (May 8, 2016)

If the runout on it is good, and thats all it is, if it was me, (As already suggested) I would just touch it with a dremel or something if you want to. I can swap it out, no question at all about that, but then you might be a little worse off than before with the runout.  That is what I would worry about the most, is how true it runs. If it is off in that aspect, swap it out, if its good there, I'd work on it a bit.     

 If you dont have a dremel, Maybe even just break the edge of the chuck body with a file where that relief would be, that would have about the same result.


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## Tony Wells (May 8, 2016)

I agree with Matt. Hardest thing to get right on a chuck is the runnout, especially at different diameters. If that chuck is good on that characteristic, and at several different diameters and lengths, you have a lot of good to work with. It appears to be a minor oversight in the production of the jaw. Nothing to really lather up about.

Bob also pointed out something I was thinking. Chuck jaws are supposed to be hard. You shouldn't be able to file it. I would take a dremel or similar tool with a Aluminum Oxide wheel dressed to the appropriate angle as the best way to address this, but a small edge break on the body of the chuck would be the simplest, easiest way to handle it. Chuck bodies are cast iron, cast steel or semi-steel. All easily cut with a file. For all the paranoids out there, run some masking tape across the slot to keep the filings out of the scroll. Stick magnets where they will catch the rest. Just think ahead a little and you won't have a problem. Oh, a diamond file would cut it, but not well, and not fast.....most of them are pretty fine.

Of course, if the chuck won't perform, swap it out. Odds are that you won't be any worse off on runout, and that you won't see a bad chuck jaw again.


Matt, I guess this could be one more small thing to add to your final outgoing inspection, which I don't doubt is already lengthy.


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## lpeedin (May 8, 2016)

qualitymachinetools said:


> If the runout on it is good, and thats all it is, if it was me, (As already suggested) I would just touch it with a dremel or something if you want to. I can swap it out, no question at all about that, but then you might be a little worse off than before with the runout.  That is what I would worry about the most, is how true it runs. If it is off in that aspect, swap it out, if its good there, I'd work on it a bit.
> 
> If you dont have a dremel, Maybe even just break the edge of the chuck body with a file where that relief would be, that would have about the same result.



Thanks for the response Matt. Runout is the whole reason I hadn't already contacted you or done any grinding. I am thrilled with the LACK of runout. This Chuck has less than .001 runout. I've never seen that in another 3 jaw. I'm kinda dreading the day I need to install the 4 jaw. 

I think I will live with the tightness for a while, but I do appreciate your & all the other's responses.


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## FLguy (May 10, 2016)

Last Saturday I said I had the same problem and that I was going to use diamond powder, well I did that this morning but what I found with chuck disassembly was the scrolls outer edge, (the side the jaws fit up with), and it's matting surface were rough and showing 2 polished spots. I used 3000 grit diamond paste there only. A little Lithium grease and it's very smooth now.


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## lpeedin (May 10, 2016)

FLguy said:


> Last Saturday I said I had the same problem and that I was going to use diamond powder, well I did that this morning but what I found with chuck disassembly was the scrolls outer edge, (the side the jaws fit up with), and it's matting surface were rough and showing 2 polished spots. I used 3000 grit diamond paste there only. A little Lithium grease and it's very smooth now.



Thanks for the feedback.


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