Lathe chuck sizing

Ultradog MN · Oct 24, 2021

My lathe will spin 14.5" according to manufacturer's specs.
It came with a 10" 4 jaw and two 8" 3 jaws.
Recently got wind of a couple of chucks that might be for sale. More like just a rumor at this point.
A 12" 4 jaw and 10" 3 jaw.
Dont know what style mount is on them or anything about their condition.
The 10" 3 jaw might be handy but is a 12" 4 jaw too large to get much use out of?
What are the recommended chuck sizes for this size machine?
Thanks

john.k · Oct 24, 2021

You d be the best judge of that ...some lathes have a bed gap under the chuck ,and can tolerate a lot more stickout of jaws......if your lathe has bed shears continued under the head,then jaw stickout will limit what capacity can be used......Too big a chuck actually reduces capacity ....which would be a 12" on a 14" lathe.

L Vanice · Oct 24, 2021

Give some thought to the weight of the chucks in addition to the diameter. Can you lift them without a hoist? Do you have a hoist in the right spot to use for changing chucks? At some point, you may decide that a chuck is just too heavy to bother installing or removing from your lathe. And the larger and heavier the chuck, the more effort is required to get it up to speed and stop it.

Another consideration is the maximum safe speed of a chuck. The larger the chuck, the lower the safe speed. Steel body chucks can run faster than cast iron or "semi-steel" body chucks of the same size. Old chucks will not have the speed marked on them, though a name brand may have the speed shown in the catalog that was current when the chuck was made. It might be difficult to find that information, of course. New chucks will often have the speed marked on them, especially if from a good maker.

Larry

Ianagos · Oct 24, 2021

Eh I think it really depends on the lathe.

I had a 14” swing lathe that I ran a 12” 3 jaw on all the time. But that lathe was pretty beefy. I’ve also had a Chinese 14” swing lathe that I wouldn’t even dare putting at 12” Chuck on maybe a 10” 4 jaw

Ultradog MN · Oct 25, 2021

Thanks fellas.
There is always more to it than a guy thinks

It is a Monarch CK 12 so actually pretty beefy. 1000 max rpms. Not a gap bed.
In addition to the chucks mentioned it came with about a 12" face plate, about a 8" drive plate and a full set of collets.
I probably don't need the bigger chucks but I just like tools. I'm sure others can relate ...

GregSY · Oct 25, 2021

I agree, a 12" is too big unless your lathe is especially stout.

More, I dislike too large of a chuck as it slows down the acceleration of the spindle....that's wasted time and tougher on the motor.

Then again, the larger chuck can add the deadening effect of sheer mass....

But mostly a 12" is too big for a 14" lathe.

edwin dirnbeck · Oct 25, 2021

GET THE CHUCK.TOOLING ,TOOLING TOOLING.These days most REAL METAL REMOVAL is being done on a cnc machine.The advantage of a manual lathe is that you can quickly chuck the part and geterdone.The more chucks and tooling that you have,the faster it goes. Often you can get chucks for cheap or pennies on the dollar WHEN YOU DONT NEED THEM. The time to get them is when they are available.Edwin Dirnbeck

JohnMartin · Oct 25, 2021

The chucks you have are just about right for your lathe.

If you are thinking of swapping them for larger chucks, don’t. Jaw clearance, safe top speed, convenience - all have been mentioned and are valid concerns.

But if you plan to keep your present chucks, you may come across a job where having a larger chuck would help. The operative word is MAY. Because you may never need them. But if they are cheap enough, they may be worth considering.

rabler · Oct 25, 2021

My '44 Monarch 12" CK uses a D1-6 chuck.

Remember that a chuck, 3 or 4 jaw, the jaws may stick out some from the chuck. While I don't like to use the part of the jaw extending outside the chuck for gripping something, it does increase the diameter.

rabler · Oct 25, 2021

My 612-2516 (25" swing) came with a 12" 3-jaw. I can't see mounting that on the CK. They are both D1-6.
I would like to pick up a 16" 4 jaw for the 2516 at some point.
And a 6" 6 jaw that I could use on either.
... AND ...

Bill D · Oct 25, 2021

I have heard a good rule of thumb is the biggest useful chuck is the same diameter that can swing above the saddle and not hit the toolpost, compound etc.
Bill D

Cole2534 · Oct 26, 2021

I have a 10" 3j on my 12CK now (ps, you're going to love that lathe), but in reality I need to mount up my 8". The thru hole isn't very large, 1-5/16" give or take a few, so the smaller chuck won't be limiting there and they certainly spin up faster.

Programmed via Mazatrol

Limy Sami · Oct 26, 2021

IME&O, bang for $, TOS chucks take a lot of beating 3 Jaw Chucks - Results Page 1 :: KBC Tools & Machinery

MK ULTRA · Aug 2, 2022

Ultradog MN said:
My lathe will spin 14.5" according to manufacturer's specs.
It came with a 10" 4 jaw and two 8" 3 jaws.
Recently got wind of a couple of chucks that might be for sale. More like just a rumor at this point.
A 12" 4 jaw and 10" 3 jaw.
Dont know what style mount is on them or anything about their condition.
The 10" 3 jaw might be handy but is a 12" 4 jaw too large to get much use out of?
What are the recommended chuck sizes for this size machine?
Thanks

Just turn the jaws around. screw them and out turnaround. then you can hold a bigger piece I used to do it all the time

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Lathe chuck sizing

Ultradog MN

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john.k

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L Vanice

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Ianagos

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Ultradog MN

Cast Iron

GregSY

Diamond

edwin dirnbeck

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rabler

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rabler

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Bill D

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