Which chuck to buy for first lathe ?

Like previous posts- it depends what you want to do. If money is tight get a 3 jaw, odd stuff can go on the faceplate. Now I have a set of ER32 collets they seem to get used most of the time.

Brian

My choice, without a doubt, would be a 3-jaw self centring - most of my work needs this. The next would be a 4-jaw independent which is needed for "non round" work ( but, as has been said a faceplate can be used - maybe with some difficulty however! After a few jobs like this I suspect you would find a way of "diverting" funds to a now essential item). A 4-jaw self centring is a bit of a luxury which may afford a firmer grip on large work but most folk manage to live without one.

Good luck with your new "obsession"!

Regards

Norman

The short answer is you will end up with both eventually, so if you can afford it, buy both straight away!

A 4-jaw will do anything a 3-jaw can do, and more, though there are a whole host of wrinkles for doing some 4-jaw jobs with a three jaw (like putting a spacer on one jaw to machine an off-centre hole, or holding rectangular bar stock for facing with one jaw on one side and two on the other).

The downside is that, despite the protests of those who are good at it (and I'm getting better) it is fiddly to set stock up in one to run concentrically, especially for a beginner.

A long as you realise all round surfaces that must be concentric need to be turned without taking the work from the chuck in between, then a 3-jaw will make your life much easier. The 4-jaw will, no doubt, quickly bubble up your priority list as you find yourself wanting to machine other shapes, and you may well have it for some considerable time before you start to use it for round work.

It's also worth noting that the 4-jaw probably have slightly greater capacity for a given diameter. A 4-jaw can grip better than a 3-jaw, but only if it's been properly adjusted - it's possible to have one jaw loose, allowing work to wiggle out, and you can be tempted to hold things in the most precarious of ways.

Even so, I would say beginner start with a 3-jaw as its easy to use and therefore safer and less frustrating during eth period when you are getting to learn how to use the machine.

Neil

... or mark the work and one jaw with a felt tip marker before taking it out so that it can be replaced in the same position.

Russell

When I answered this question this morning I thought it was a no-brainer. My comment was merely about the dial gauge.

With a three jaw self-centering chuck you can hold round bar with an accuracy dependent on the construction and wear of the chuck. OK you can take precautions or other actions to ensure that your turned surfaces are concentric but you are bound to be bitten sooner or later by the chuck's inherent inability to accurately hold a round bar. It must be said that it can also hold non-round (usually rectangular) objects for facing.

An independent four jaw chuck can be set up to hold round or rectangular bar at a required accuracy. Once mastered, and it is not difficult with a dial gauge, the setting up is not difficult and takes, at the most, a couple of minutes.

I don't understand the faceplate suggestion. The use of a faceplate, I think, is beyond a beginner. It takes some skill and quite a bit of time to set-up and balance something on a faceplate.

What I don't understand is why lathe manufactures and dealers always sell lathes with a three jaw self-centering chuck? OK, it is what the buyer wants (not needs).

JA

My call would be a 4 jaw self centering chuck - it will self centre round, square, oval bar and some weird forms (ie Stuart steam governor extrusion). I got one of these years ago and the only thing it can't help with is turning cranks. It is possible to use packing pieces to move the work off-centre, but I've no real experience of doing that.

A minor benefit is that the clamping forces are more even with four jaws rather than three (think about thin wall tube as an example).

There is no "right" answer this - get an independant jaw chuck and have to clock every job and be able to turn off-centre or take the benefit of the 90%+ times you won't need to clock a job but be stumped when you need to turn an eccentric.  I've never been convinced about self centring chuck runouts being a problem.

So it's really back to what you plan to do,  before you buy a second chuck.   In fact I just remembered how to turn cranks in a self centring chuck - l'll see if I can find a picture to upload...

Steve

Edited By Steve Withnell on 06/12/2014 16:31:38

Just read my reply, as Ian says it should have read 3- jaw self centering, was in a rush to get out.

J

One method of turning a crank in a self-centering chuck...

http://whittlev8.files.wordpress.com/2011/02/crank-cam.jpg

Steve

I have two points to make. First is buy a good quality three jaw chuck because if it has a separate backplate, you can fine tune it to hold concentrically like a four jaw. Secondly, and so far not mentioned is convenience and repeatability. If you have twenty or thirty turned items that each need several operations performing on them, the joy of setting a four jaw chuck each time gets stale very, very quickly. That's why most lathes come with three jaw chucks. It's the one most of us use 90 percent of the time.

JA - setting a job up on a faceplate is difficult for a beginner, but so is using a 4 jaw chuck. Difference is the faceplate is much cheaper, and you will learn a lot.

Well, Brian: I think you have probably received at least one recommendation for every option.

... not forgetting, of course, that some excellent work can be done 'between centres'.

Let us know what you decide.

MichaelG.

I have a Unimat, Basic which is of a comparable size to the Sherline, and like the Sherline can be fitted with either a 4 jaw independent chuck or a 3 jaw self centring chuck. The latter, like with the Sherline, is tightened by means of two tommy bars which are an absolute pain to use.
So if anything, I find that for those of us with only two hands, the 4 jaw chuck is actually easier and faster to use when compared to juggling two tommy bars endowed by gravity with a natural predilection to head straight down into the swarf, and of course two tommy bars are twice as many things to lose and also much harder to find than a 4 jaw chuck key.

Initially when I first got the lathe which was supplied with both chucks I shied away from using the 4 jaw. But after I bough a dial indicator off eBay I decided to give it a try. I soon found that with a little practise especially on these smaller chucks with limited travel, an item can be centred very quickly, and of course the 4 jaw can hold things that would be almost impossible with the three jaw.
My three jaw has long since been relegated to paper weight duty, which has had the beneficial side effect of no more of the scraped knuckles that inevitably occurred, no matter how careful I was, almost every time I tried to open the chuck to remove a piece of work.

Clive

Edited By clivel on 06/12/2014 18:53:22

Hello folks.

Can I through a little more mud in the water?

I used to use a 4-jaw for holding hot-rolled, forged or cast items to protect the accuracy of a 3-jaw while the rough skin was taken off.

A 3-jaw is for convenience and mounting speed which is far less important in a hobby environment. Also 3-jaws allow for the use of soft jaws which have a myriad of uses in the professional environment.

Excellent points, Clive

MichaelG.

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P.S. ... Straying somewhat from the original topic; these are worth a look !!

Edited By Michael Gilligan on 06/12/2014 20:32:22

Makes you wonder why so many lathes come with a 3 jaw when 4 jaw chucks are generally cheaper? Could it be that for a beginner, they're the better option? It takes about two seconds to grip something in a 3 jaw whereas....

I am a bit confused here : why is the 3 jaw self centering chuck more difficult to use than the 4 jaw self centering chuck ? I would have thought they would both be easy to use : isn't one chuck key enough to tighten up on the work piece ?

NOTE 1 : I have ruled out buying the 4 jaw independent chuck.

NOTE 2 : The 4 jaw self centering chuck is only $40 more than the 3 jaw.

Edited By Brian John on 07/12/2014 02:56:29

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In that case, Brian ... The choice between 3-jaw and 4-jaw self centering chucks is fairly simple.

• The 3-jaw will easily and securely hold round and hexagonal material.
• The 4-jaw will easiily an securely hold square material.

Yes, the 4-jaw will probably hold round material, but less reliably than the 3-jaw.

... holding most other sections will require some initiative.

MichaelG.

Aha, that is what I wanted to know. The 4 jaw does not hold round material well so the 3 jaw chuck it is. Thank you.

Brian, its not the selfcentering 4-jaw that is more difficult to use it is the 4-jaw independant. as you have to make small adjustments to each of the 4 jaws in turn until you get the work running true.

To start with I would suggest you rule out the 4-jaw SELF CENTERING, then make your choice between 3-jaw self centre or 4-jaw independant.

My choice would be the package they do that includes the 3-jaw self ctr chuck

Hi Michael

Why won't a 4 jaw chuck hold round material as well as a 3 jaw?

I seem to rememeber that clever chap in the US who made the laser centering device for the mill spindle has a website, someone posted a link and I had a look. One of the things he said was that he preferred a 4 jaw independant over the 3 jaw indepandent because it would grip round, hex and square bar.

Grey matter could be off, it's not doing very well at the moment

Cheers Michael.