# 3 jaw chuck runout



## will (Feb 20, 2009)

I have a 3 inch 3 jaw chuck on my 7x10 lathe. It never really ran true and I have been trying to figure out how to fix it. The chuck body runs true to the spindle, checked with a dial indicator. The jaws have about .015 play up and down. I wedged the jaws and tightened them down as if there was a piece of stock being held. I clamped a dremel, with a grinding wheel, to the carriage. I made a few passes to grind the jaws down a little bit. I was hoping to get it dead on, however, I ended with about .001 runout. 

I am reasonable sure this is all due to wear and it is probably as good as it is going to get. 

I most likely will replace the chuck with a 4 inch chuck...

Is there a better way to true up the jaws...?


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## precisionworks (Feb 20, 2009)

What you did is the best way to correct the problem, but only works at the exact diameter that you clamped the jaws on. Smaller than that & larger than that will show more run out.:sigh:


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## LLCoolBeans (Feb 20, 2009)

will said:


> Is there a better way to true up the jaws...?



Probably, but would it be worth your time? You can get a decent 4" 4-Jaw for about $75.

You'll have to use a dial indicator to center your workpiece, but you'll never have to worry about runout again.

Even the expensive 3-Jaw chucks are never all that great for concentricity, in my experience.

Go for a 6-Jaw if you need self-centering.


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## will (Feb 20, 2009)

precisionworks said:


> What you did is the best way to correct the problem, but only works at the exact diameter that you clamped the jaws on. Smaller than that & larger than that will show more run out.:sigh:




Thanks - that is what I figured. Fortunately, most of what I do can work with this little bit of runout. Where I need closer, I can mount the work and use shims to get it dead on. 

There is a 6 jaw chuck on ebay ( 4 inch )


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## gadget_lover (Feb 20, 2009)

For work where you are only mounting the piece once AND where you are not matching an existing interior or exterior dimension, it does not matter much if there is a bit of runnout. The trick is to not remove it from the chuck till you are done with it. By definition, all the work you do will be concentric.

If you need to re mount it, put it back in the same orientation as original and use shims as necessary. Of course, you can use a chuck with independant jaws for second operations and get it dead on.

Daniel


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## tino_ale (Feb 20, 2009)

LLCoolBeans said:


> Go for a 6-Jaw if you need self-centering.



What does 6-jaws vs. 3 jaws has to do anything about centering? Does self-centering exist in spindles?


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## LLCoolBeans (Feb 20, 2009)

tino_ale said:


> What does 6-jaws vs. 3 jaws has to do anything about centering? Does self-centering exist in spindles?



Not sure, just that the 6-Jaw chucks I have used have done a better job of self-centering than 3-Jaw. Maybe, they were just better quality?

Still, a manual centering 4-Jaw is the way to go for hobby work, the only disadvantage is setup time. With a little practice you can get pretty quick centering with a dial indicator.


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## will (Feb 20, 2009)

The 6 jaw has the advantage of being able to hold thin wall items better than a 3 jaw, less likely to crush the object. They are more costly, and may be better made than a standard 3 jaw. 

I generally make 6 to 10 items at a time. The parts are removed from the chuck at different times for different operations. I do agree that a 4 jaw would yield better results, the additional setup time would not work for me. 

thanks for all the info...


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## LLCoolBeans (Feb 20, 2009)

will said:


> The 6 jaw has the advantage of being able to hold thin wall items better than a 3 jaw, less likely to crush the object. They are more costly, and may be better made than a standard 3 jaw.
> 
> I generally make 6 to 10 items at a time. The parts are removed from the chuck at different times for different operations. I do agree that a 4 jaw would yield better results, the additional setup time would not work for me.
> 
> thanks for all the info...



Would a collet chuck work? If you are using some standard OD, that would give you speed and accuracy.


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## will (Feb 20, 2009)

LLCoolBeans said:


> Would a collet chuck work? If you are using some standard OD, that would give you speed and accuracy.



Most of what I do is modify existing Maglites. I do very little from plain stock,I would really like to use a collet, but it would not work in my case.


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## LLCoolBeans (Feb 20, 2009)

will said:


> Most of what I do is modify existing Maglites. I do very little from plain stock,I would really like to use a collet, but it would not work in my case.



Dang! Yup, that's too big for a collet.


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## steelgaze (Feb 20, 2009)

How much do the diameters that you are machining change? If you are doing consistently the same size, I would recommend trying to find a set of soft jaws (free machining steel compared to hardened) you will have to bore them out to size, but it will hold your runout more consistently. This is of course assuming that someone makes jaws that fit your chuck.


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## will (Feb 20, 2009)

This is an Enco 7x10 lathe, small 3 inch chuck. I have never seen soft jaws for it. 

The reality of it all - it is time for a new chuck. 

I have been holding off spending any money for this lathe, I could use something larger. I get tired of making do because of the small size and the limits of length and diameters. 

The nice ting about it - I can move it around easily, I don't have to dedicate floor space in my small shop area..


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## Anglepoise (Feb 20, 2009)

will said:


> The reality of it all - it is time for a new chuck.
> 
> ..




Can't help with that decision.....but its worth bearing in mind that scroll chucks, be they 3,4,or 6 jaw, on average, brand new out of the box, have at best 0.003" runout. This is industry standard and if unsatisfactory then a 4 jaw independant will be the way to go. As has been mentioned above, grinding will only help at the diameter of the jaws when ground. 

Also remember that the measuring tools to check runout have to be accurate and many are not.

So your chuck is probably just fine.


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## sawlight (Feb 20, 2009)

will said:


> This is an Enco 7x10 lathe, small 3 inch chuck. I have never seen soft jaws for it.
> 
> The reality of it all - it is time for a new chuck.
> 
> ...


 
I disagree on all counts on this post. If all you are doing is mag lights, make a set of alum. jaws for the lathe. Load them from the outside, a steel ring etc. and bore them. (The loading helps in concintricity) Bore them just a hair small, not much. Then be prepared to bore them each time you change them out.
Three jaw chucks are awesome from a productivity stand point. But run out of .003 to .010 is to be expected unless the jaws are "trued" to the chuck.
FWIW: The alum. jaws give the option of NOT marring the anodizing of most finishes!


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## cmacclel (Feb 20, 2009)

My Bison 8" direct mount D1-6 chuck has 0.00" runout.

My Grizzly with a cheap 6" 3 Jaw was within 0.001"

My Harbor Freight 3 on 1 machine I get 0.006''

These all all taken from 6" away from the chuck with a piece of ground 1" Drill rod.

Mac


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## cmacclel (Feb 20, 2009)

sawlight said:


> I disagree on all counts on this post. If all you are doing is mag lights, make a set of alum. jaws for the lathe. Load them from the outside, a steel ring etc. and bore them. (The loading helps in concintricity) Bore them just a hair small, not much. Then be prepared to bore them each time you change them out.
> Three jaw chucks are awesome from a productivity stand point. But run out of .003 to .010 is to be expected unless the jaws are "trued" to the chuck.
> FWIW: The alum. jaws give the option of NOT marring the anodizing of most finishes!


 
His lathe has 1 piece jaws, so soft jaws are not an option. You need to step up to around a 6" chuck before 2 piece jaws are offered tyically.

Mac


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## gadget_lover (Feb 20, 2009)

I thought that too, but he did specify "make a set", which could be the whole jaw. 

It does not have to be too accurate if you are going to bore a hole in the middle that matches the piece you are working.

Daniel


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## cmacclel (Feb 20, 2009)

gadget_lover said:


> I thought that too, but he did specify "make a set", which could be the whole jaw.
> 
> It does not have to be too accurate if you are going to bore a hole in the middle that matches the piece you are working.
> 
> Daniel


 
You would be better off buying a new chuck maybe a new lathe before making 1 piece jaws  That would be alot of work even with a CNC mill 

Mac


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## sawlight (Feb 20, 2009)

gadget_lover said:


> I thought that too, but he did specify "make a set", which could be the whole jaw.
> 
> It does not have to be too accurate if you are going to bore a hole in the middle that matches the piece you are working.
> 
> Daniel


 


cmacclel said:


> You would be better off buying a new chuck maybe a new lathe before making 1 piece jaws  That would be alot of work even with a CNC mill
> 
> Mac


 

My bad, I am used to, well, what I am used to!!
No, if you cannot bolt them on, it's a waste of time and energy!! I can machine on a Bridgeport, a set of alum. jaws in a matter of FEW hours for bolt ons.
Trying to machine the whole jaw, plan on two days, easy!


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## will (Feb 20, 2009)

Guys 

I am reasonably handy - 

I have the lathe, a drill press, a radial arm saw, and a few other power tools used for wood working. 

Soft jaw chucks I have used in the past were larger than the 3 inch chuck on my lathe. They are easy enough to make of you have a milling machine. They are great if all you do is one diameter stock. I work with mini-mags , both the head and the body, full size Maglites ( C & D ). and recently Surefire 6P type bodies. Some parts are held on the outside, some on the inside, I bored out the chuck so I could at least pass 3/4 inch stock. 

I also custom make Magician Wands, The lathe serves for my woodworking needs as well. 

I do not make enough of any one thing at the same time to justify custom jaws for a single diameter.

Making a full set of jaws is beyond the equipment I have here. 

By grinding the jaws, I was able to get them from .006 to .001 run out. not too bad from 3 inch chuck that is showing signs of wear. I asked the question to see if there was a better way to fix the chuck. 

This is not a collet machine, I really need the flexibility of a self centering chuck. I just wanted it to be more accurate than it was.


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## will (Feb 21, 2009)

sawlight said:


> My bad, I am used to, well, what I am used to!!
> No, if you cannot bolt them on, it's a waste of time and energy!! I can machine on a Bridgeport, a set of alum. jaws in a matter of FEW hours for bolt ons.
> Trying to machine the whole jaw, plan on two days, easy!



I don't remember how long it took to make a set of soft jaws, certainly a couple of hours using a Bridgeport milling machine. 

My brain started to freeze trying to figure out how to make the back part of the threads, On a milling machine with a rotary table. Or maybe on a lathe with a fixture to hold them , really not something I am going to do or even think about any more. 

The work I do on the lathe runs from 1.250 inch down to .125 inch.


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## 65535 (Feb 21, 2009)

See if you can adapt a Taig 3" soft jaw chuck to your lathe. With replaceable jaws you can simply bore the jaws to have minimal run out on the diameter you want.


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## will (Feb 21, 2009)

65535 said:


> See if you can adapt a Taig 3" soft jaw chuck to your lathe. With replaceable jaws you can simply bore the jaws to have minimal run out on the diameter you want.



Thanks -I looked at that chuck online. I have no way of determining if it can be adapted. 

I can live with the .001 run out I now have.


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## 65535 (Feb 21, 2009)

The nice thing about the Taig is the price, and with aluminum jaws you can machine them however suits you, they should do minimal if any damage to flashlight parts and they are replaceable without replacing the chuck. All that you would need to do to adapt it would be to create a 3/4-16 threaded spindle to mount the chuck to.


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## will (Feb 22, 2009)

I just cut the outside part of the jaws, the area that allows the work to be held on the inside. They were off as well. It's almost like a new machine now. 

I am going to get a 4 inch, 4 jaw independent chuck. I do a lot of work with wood, 1 1/2 inch square for the most part. The 4 jaw chuck will eliminate the steps getting part of work round to be held in the the 3 jaw chuck.


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## mdocod (Feb 23, 2009)

Just wanted to say, I probably have the same chuck on my quick-indexing table as you have on your lathe there, and mine has similarly bad run-out. For the work I do, it's not an issue at this time, but it was a huge disappointment discovering it for the first time as it was enough to throw things off more than I would have liked, until I discovered where the problem was and "split the difference" in the initial centering. I guess these things are just junk, too bad, as I like the 3 jaw configuration as it's perfect for my work, the jaws are out of my way for most of the milling operations. A 4 or 6 jaw would probably never work for my needs.


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