Limitation in self centering jaw chuck

[Alberto-sp]

Hi everyone. (Sorry my english)

I own a minilathe. It has a 3 Jaw 100mm self centre chuck, and I bought a 4 jaw independent chuck.

The 4 jaw is great, and it cand hold very big parts before the jaws loose the internal screw, but the 3 self centre no. The maximum aperture in the 3 jaw is much smaller than the 4 jaw. but for most of my work, I prefer self centering because is more easy and quick.

So my question is. Is it possible to find, with the same size of chuck, one with self centering jaws but with more aperture? Or the smaller aperture is charasteristic of the self center chucks? I don´t mind 3 or 4 jaws.

Thank you

Best regards

 

[Firstram]

Do you have outside jaws for the 3 jaw chuck?

 

[jwmay]

I don't know if you can find what you want. But for me, best is to have 4 chucks. Two 4 jaws; one with inside jaws, one with outside jaws. Two 3 jaw chucks...same scenario. And then a collet chuck. So five chucks...yeah..five chucks minimum. Lol

 

[Alberto-sp]

Yes, I have outside jaws but they have less grip "surface" and about having more than 1 chuck, in my minilathe changing the chucks is a PITA.

 

[woodchucker]

I don't know if you can find what you want. But for me, best is to have 4 chucks. Two 4 jaws; one with inside jaws, one with outside jaws. Two 3 jaw chucks...same scenario. And then a collet chuck. So five chucks...yeah..five chucks minimum. Lol

oh come on now, stick to the question, stop giving advice on buying 5 chucks and stick to his question...

You can get a bigger chuck, but it's a matter of your lathe. when you go bigger you risk the jaws hitting the cross slide.
So a few things will have to be known.

what is the size of your mini lathe?
need to know either radius or diameter swing. just tell us what you are giving.
next we need to know the center to cross slide distance.. measuring (where the tailstock center point to the top of the cross slide where it would hit . Then that same center point to your carriage arms (that's the most important)..
For some reason, they always recommend a smaller 3 jaw, and a larger 4 jaw.
My 9" lathe for instance handles a 5" 3 jaw, and a 6" 4 jaw. Why? I don't know the answer to that. But your 3 jaw should not hit your carriage arms, and your jaws should clear the carriage.

 

[jwmay]

Seriously. Sometimes I need two chucks just for one job.
But yeah I guess the answer is that you have to buy a larger chuck. But of course, besides the things woodchucker pointed out, you will always be limited by the ID of your lathe spindle.

 

[Ken from ontario]

Here's a 4 jaw self centering 4"chuck:

4-Jaw Self-Centering Lathe Chuck | Lathe Chucks for Sale

Hold work up to 80 mm in diameter. Made of high-grade steel, this 4-jaw self-centering lathe chuck includes a chuck key and inside and outside jaws.

littlemachineshop.com

and 6 jaw 4" :

Lathe Chuck, 6-Jaw 4", Self-Centering 2276

Lathe Chucks 2276 6-jaw self centering lathe chuck; 4" (100 mm) diameter; Includes chuck key and mounting bolts; Plain back mounting; Excellent for ho...

littlemachineshop.com

 

[brino]

in my minilathe changing the chucks is a PITA.

Do the different chucks bolt on to a single fixed plate that is part of the lathe spindle?

Some pictures of your current chucks would help us to help you.

Brian

 

[Nogoingback]

6" sounds like a lot for a mini lathe, but a 125mm might work.
Perhaps something like this: https://littlemachineshop.com/products/product_view.php?ProductID=2337&category=566826475

If you want a chuck
that's the same size but with a larger aperture, you'll just need to research
manufacturers drawings until (if) you find one.

 

[NC Rick]

A couple thought I’m having:
scroll chuck (self-centering) is likely to have less jaw excursion and you NEED to have a couple “teeth” engaged on each jaw.
3 jaw chuck holds a lot of things better than a 4 jaw. Using the outside clamping jaws of the three jaw works well for shorter parts because the “shelfs” support the part against cutting forces.

a 3jaw scroll chuck in 6” size needn’t be very expensive and if you are careful not to extend the jaws where they hit your ways or cross-slide could benefit you by having a larger a d deeper aperture through the chucks body. I do not like the idea of a chuck in a chuck on any lathe but on a mini lathe the loss of rigidity and forces on the spindle bearings seem totally unacceptable to me. So, my answer is to have 3 chucks.

by the way, your English is fantastic! Welcome.