# Chuck Too Big ?



## DZ55 (Jan 18, 2016)

A couple months ago I purchased a Rockwell 11x36 lathe. It came with a 6" 6 jaw chuck.  Then this past week I came across  a 10" Union 4 jaw combination chuck at a price I couldn't turn down. My question is Can a chuck be too large for a certain lathe?( not meaning swing size) The 4 jaw I bought weighs 95lbs. Is there some type of guideline  to go by? Can my 11" lathe handle any chuck that will fit? Thanks.


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## Bob Korves (Jan 18, 2016)

If the chuck is too big, the outside edges of the jaws will want to hit the ways before you have a very large part held in them.  Sometimes that can be mitigated by using the steps of the jaws, but with less surface area being clamped, or reversing the jaws.  Securely holding a part when the diameter is near the swing size of your lathe is sometimes actually more difficult with a large chuck due to chuck jaw to way clearance issues.  Hope that makes sense...


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## f350ca (Jan 18, 2016)

My 16 inch lathe came with a 15 3/4 inch 4 jaw from the factory. Only complaint is it will only close to 1 inch so someday I'll pick up a smaller chuck for it. The weight of the chuck would have to be subtracted from the weight capacity of the lathe.
In my case the capacity at the spindle is 1000 pounds, the chuck weighs 140.

Greg


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## 4GSR (Jan 18, 2016)

Your 11" Rockwell can handle the chuck.... But you not going to like it!


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## RIMSPOKE (Jan 18, 2016)

f350ca said:


> My 16 inch lathe came with a 15 3/4 inch 4 jaw from the factory. Only complaint is it will only close to 1 inch so someday I'll pick up a smaller chuck for it. The weight of the chuck would have to be subtracted from the weight capacity of the lathe.
> In my case the capacity at the spindle is 1000 pounds, the chuck weighs 140.
> 
> HERE's A PLUS . AT 100+ POUNDS , THE FLYWHEEL EFFECT WILL OVERCOME THE SHUDDERING OF AN INTERRUPTED CUT .


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## mikey (Jan 19, 2016)

From the Logan Lathes FAQ: http://www.lathe.com/faq/#_Toc95180284

* What is the right size chuck for this lathe?*

_Logan supplied a 5” 3-jaw chuck and a 6” 4-jaw chuck for their 10” lathes.  Logan supplied a 6” 3-jaw chuck and a 6” 4-jaw chuck for their 11” lathes.  Larger chucks were available, but they are impractical on these lathes because the jaws would hit the bed when the chucks were opened.  Larger chucks are also heavier, so they put a strain on the spindle and spindle bearings.  In general, use the smallest possible quality chuck for the job._

I also own an 11" lathe and the largest chuck I have is 6.5". It has enough capacity to turn the largest piece I've ever had to turn so it works for me. I definitely would not go with a 10" chuck due to the potential for a jaw to contact the ways.


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## DZ55 (Jan 19, 2016)

Thanks for all the input, heard some things I didn't think of, and it all makes sense. I Love this site!!


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## 4GSR (Jan 19, 2016)

If you were a little closer, I'd offer to play swap out for one of my 8" Adjust-True chucks for your 10" combination chuck.  Shipping would be a killer at the moment!


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## RIMSPOKE (Jan 19, 2016)

If you were a little closer, I'd offer to play swap out for one of my 8" Adjust-True chucks
for your 10" combination chuck. Shipping would be a killer at the moment!

EXPERIENCE THE MIRACLE OF FLAT RATE PRIORITY BOXES AT THE POST OFFICE .
THE LARGE SIZE BOX IS 12" x 12" x 5.5" & SHIPS ANYWHERE IN THE USA FOR $18.75 .

A 10" CHUCK WILL FIT IN A 12" BOX . YOU MAY HAVE TO REMOVE THE JAWS & POSTS .
THE ONLY BUGABOO IS THE 70 POUND LIMIT . IF IT's CLOSE , YOU COULD SEND THE PARTS SEPARATELY .


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## chips&more (Jan 19, 2016)

IMO that chuck would be too big. Many reasons say no. The inertia would be dangerous. The weight of the chuck on the head stock bearing(s). You are not going to find a mounting/back plate and would need to fabricate one. If the lathe has a threaded spindle, heaven forbid if you ever ran the lathe in reverse…Dave.


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## kingmt01 (Jan 19, 2016)

I don't know what that lathe looks like. With removable ways it might work but if not it is likely to big. It could be just the ticket for a one off job tho. I needed a 4 jaw the other day that would hold a .250" hardened pin. My 4 jaw on my 14x40 was to big. So I grabbed the 6" 4 jaw from my 9x lathe & suck it in the big chuck. Took some indicating to get it as true as I needed but it worked a charm.

I was turning a arbor for a well worn drill chuck that a .250 pin wrapped in paper will just barely fit. I was quite proud of it when I finished. It only has .0041" total runout 2" from the chuck. As rough as the chuck looks I think that is impressive. It looks like it has been used as a hammer & was stuck tight when I got it. 

Sorry I tend to run on talking past the answer sometimes.


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## 4GSR (Jan 19, 2016)

If he has one of the Rockwell lathes with a L-00 spindle nose, it will probably be fine.  But if it is one of the much older models with the threaded spindle nose, no way!!!


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## Wreck™Wreck (Jan 21, 2016)

f350ca said:


> My 16 inch lathe came with a 15 3/4 inch 4 jaw from the factory. Only complaint is it will only close to 1 inch so someday I'll pick up a smaller chuck for it. The weight of the chuck would have to be subtracted from the weight capacity of the lathe.
> In my case the capacity at the spindle is 1000 pounds, the chuck weighs 140.
> 
> Greg


If you only do occasional hobby work buy a small 3 jaw that can be chucked in the large 4 jaw, this will allow you to adjust the runout of the three jaw and not have to change chucks as often, if making hundreds of parts in one setup this is not ideal unless you make a chuck key that extends beyond the larger chucks diameter.


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## AaronD (Jan 21, 2016)

I have a Rockwell 11" with 6" Buck adjust tru and 8" 4 jaw. I couldn't imagine a 10" would be ideal.  The lathe if L00 nose will handle it, just be mindful of clearance and rpm.

I had an 8" 4 jaw on a 9" South Bend once....I was not a fan, not to mention the belt slippage and concern of the threaded spindle.


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## f350ca (Jan 21, 2016)

Wreck™Wreck said:


> If you only do occasional hobby work buy a small 3 jaw that can be chucked in the large 4 jaw, this will allow you to adjust the runout of the three jaw and not have to change chucks as often, if making hundreds of parts in one setup this is not ideal unless you make a chuck key that extends beyond the larger chucks diameter.


I've done that once or twice but as you say a nuisance to get at the three jaw to tighten it.  I was given a D!-8 mount, actually looks like it might have been the back of an 8 inch three jaw chuck. An 8 inch 4 jaw would be much handier, and as Aaron suggested my 4 jaw is only rated to 760 rpm.

Greg


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