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What are my options for chuck replacement?

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I have a Grizzly 7x12 lathe that I bought a few months ago. It came with a 3 jaw chuck.

I want a chuck that can grip larger diameter work pieces. I guess I can just bore out the work piece and grip it from the inside with the internal jaws the chuck came with, but I just want to get a chuck that can open up considerably more. Do I have options or am I stuck with this one?

Also, a quick question about 4 jaw independent chucks. People keep recommending them, but wouldn't it be a pain to have to find the center every time you put a work piece in, compared to a 3 jaw chuck that automatically centers the work piece?
 

Comments

#2
There have been several threads on this subject.
You did not say how big you want to hold. It might be possible for you to just get some external jaws for your 3 jaw chuck that will hold larger work. I would think that the grizzly manual would show that option.
My lathe came with a 3 jaw scroll chuck and an independent 4 jaw chuck. Each has its use and using a four jaw is every bit as much fun as using a scroll chuck when it is the right tool for the job.

PS: The grizzly manual on page 18 shows the two sets of jaws, internal and external, with illustrations of the type of work holding each is designed for.
 
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#3
a 3 jaw chuck that automatically centers the work piece
Hello,

3 jaw chucks all have some limit to the accuracy that they repeat to, for some kinds of work their can be advantages to being able to center the part or even put it off center to turn eccentric parts.

Stu
 
#4
WHy does my post look so weird
 
#5
If you already have a 3 jaw for smaller stuff, a 4 jaw would come in handy for larger, or irregular shaped work. It's true that it
takes a bit longer to dial in work in a 4 jaw, but with practice it goes quickly. You can speed up the process by having a
tool holder set up with an indicator just for that task. I use my 4 jaw all the time, and I no longer consider set up time an issue.

The alternative would be a set-tru style 3 jaw in a larger size, but you'd miss out on the flexibility of the 4 jaw.
 
#6
I have both chucks and find I use the 4 jaw a lot more then the 3 jaw, After using it for a while you will find setting it up is pretty quick and easy.
 
#7
A couple of things for your consideration:

First off, there should be a set of inverted chuck jaws that came with your machine. They will greatly increase your "reach" in chuck sizing. If I'm not mistaken, that size machine has a flange on the spindle instead of a backing plate. And a MT-3 bore through behind. In any case, the three jaw, or any scroll chuck, has a runout to some degree. What matters is whether or not you can live with it. Unless you're building a jet engine, most times it won't matter. An afterthought about earlier small machines; some of them had reversible jaws in the chuck. They were not as stout as regular jaws, but for my work, a lot handier to keep track of.

Second point: Just how big do you really need to get? Maybe a larger machine would be the better choice. Look to the clearance over the cross slide. That is one of several limiting factors. How far you can open up the chuck before the jaws hit the ways is another.

Third: Way back(late 60's, early 70's) when I first had access to a lathe, there was only a four jaw independant for me to learn on. Not as fast as a scroll chuck, but a helluva lot more accurate. Setting it up is a little slower, but worth the time if you're doing close work. And a requirement for engine journals and the like eccentric work.
 
#8
My 9x20 came with an appalling excuse for a 4 jaw chuck so I added a new one so I could hold larger items.
If replacing the chuck with a larger one be aware of the extended jaws hitting the cross slide though. I learnt that the hard way.
Also 3 jaw chucks usually do not have repeatability so if replacing the work it may not run true to previous cuts.
The 4 jaw centering method allows repeatability in replacement and is easy and quick once you have got used to it.
There are many videos on line to show how to do this that are well worth watching.
If I can do the job from start to finish without removing it from the chuck I use the 3 jaw, if I have to remove the job from the chuck to check or whatever and then replace it for further work I use the 4 jaw.
If replacing the chuck you may have to make a new backplate for it to fit your lathe.
 
#9
A couple of things for your consideration:

First off, there should be a set of inverted chuck jaws that came with your machine. They will greatly increase your "reach" in chuck sizing. If I'm not mistaken, that size machine has a flange on the spindle instead of a backing plate. And a MT-3 bore through behind. In any case, the three jaw, or any scroll chuck, has a runout to some degree. What matters is whether or not you can live with it. Unless you're building a jet engine, most times it won't matter. An afterthought about earlier small machines; some of them had reversible jaws in the chuck. They were not as stout as regular jaws, but for my work, a lot handier to keep track of.

Second point: Just how big do you really need to get? Maybe a larger machine would be the better choice. Look to the clearance over the cross slide. That is one of several limiting factors. How far you can open up the chuck before the jaws hit the ways is another.

Third: Way back(late 60's, early 70's) when I first had access to a lathe, there was only a four jaw independant for me to learn on. Not as fast as a scroll chuck, but a helluva lot more accurate. Setting it up is a little slower, but worth the time if you're doing close work. And a requirement for engine journals and the like eccentric work.
Ahah! thanks! I was thinking the set of inverted chuck jaws were only for holding internal bores. Didn't think of it that way.

Also, guys, I have an 0XA QCTP and I'm using 1/4" HSS blanks. Can I use 3/8" blanks with 0XA QCTPs? I can't find 1/4" cobalt blanks, but I can find 3/8" ones.
 
#10
As long as the toolbit will fit in the holder and you can adjust the cutting face onto the lathe axis, no reason why not. I used to use 5/16 toolbits on my mini lathe. Now that I've got a larger lathe, I use anything from 1/4" to 1/2" bits depending on what I've got ground up to do the job at hand.
 
#12
An afterthought, or change of subject, or whatever you want to call it. There are times I will remove work from the chuck and then come back weeks later to make another cut. Sounds like you are facing a similar situation. I have a notch cut, on several chucks actually, on the outside corner. If something is "experimental" or if I don't really know what I'm doing, I will make a "sharpie" mark on the work so it can be put back where it was the first pass.

This doesn't always work as expected. But for tolerances of a few thou, the chance is worth the attempt. If I'm making a wheel, I try to do it in one chucking. On something more forgiving, it does pay to try.
 
#13
1/4" cobalt bits are available, I've seen them on ebay and vendors like MSC and Fastenal
 
#14
I have a 7x 14 and I actually use a 5" 3 jaw and love it. The spindle thru hole is only good for about .75" but with the 5" I am able to chuck a 1" piece a couple inches deeper until I max out the MT3 diameter. It will reduce the length that can be turned outside the jaws. The independent jaws are more accurate but I have a project that I have to make several pieces of varying diameters with fairly loose tolerances so I opt for the scroll type. LMS sells the adapter fully machined for the 7 X flange.
 
#15
put a 4" on it, but remember the larger chuck you put on it you may have clearance issues with bed or carrage. use some brains when doing it.I was going to get a 4" for mine then I just got a new 9x20 and bought 2 extra chucks&back plates for it 5"&6" chucks.(5 is 4 jaw). you can remove your chuck and if your lathe does not have a removable back plate just messure it and make a plate to bolt to it and then square it up to the size for the larger chuck, make sure you index everything!!!( add marks so you always got it back where it should be.) it's not hard to do at all.just make sure you have interfearance fits so it centers up with no slop.
 
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