3 jaw chuck runout

[will]

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...?

 

[precisionworks]

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:

 

[LLCoolBeans]

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.

 

[will]

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 )

 

[gadget_lover]

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

 

[tino_ale]

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?

 

[LLCoolBeans]

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.

 

[will]

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...

 

[LLCoolBeans]

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.

 

[will]

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.

 

[LLCoolBeans]

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.

 

[steelgaze]

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.

 

[will]

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..

 

[Anglepoise]

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.

 

[sawlight]

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..

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!

 

[cmacclel]

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

 

[cmacclel]

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

 

[gadget_lover]

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]

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

 

[sawlight]

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

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!