Need Advice on a New Chuck

swany

swany

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What's up guys. I have a Grizzly G4000 9 x 19 as a starter lathe to learn how to use a metal lathe, and it's going well so far. My main problem(s) is when I turn thin-walled tube (304 SS, 316 SS, 416 SS, and 17-4ph). Obviously, I have discovered that using the 3-jaw self-centering chuck that came with the Grizzly will almost always deform tubing. I have a friend who purchased a 6-jaw, 4" chuck for his mini-lathe because he uses his similar to what I use mine for (turning thin-walled tube). He said that the 6-jaw chuck is awesome and he is able to turn tube no problem and it doesn't deform his workpiece(s).

He is a more accomplished machinist than I am...to the point that he was comfortable making the adapter plate that was needed to install the new 6-jaw chuck. I do not have this confidence. I need to find a better chuck (preferably self-centering) that will help me to turn and part thin-walled tube. It doesn't have to be a 6-jaw chuck...I'm not opposed to other ideas or even some tricks that could help me turn some tube with what I already have.

I also have the Grizzly 4-Jaw 6" chuck, but I haven't learned how to use it yet because the jaws are individually adjusted. I can't find the tool that is needed to do that so I may have to order one. So, I need a chuck and corresponding plate that will allow me to use the chuck (without having to modify parts).

This is the 6-jaw 4" chuck my buddy purchased:

Lathe Chuck, 6-Jaw 4", Self-Centering 2276 - LittleMachineShop.com

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...
tinyurl.com

By the way, my budget is like < $250

Thank you.
 
You are going to have to machine a backplate, no way around it.
 
I think Stu has a very good solution if you are doing a lot of the same size tubing. Aluminum or even pvc would work.

I have basically the same lathe, a 9x20 HF. Mine came with a 5” 3jw and 6” 4jw And the original 4” 3jw. The guy I bought it from had tricked it out according to Steve Adair’s 9x20 page. But as I used it, it became evident he had not done any of the preliminary things like truing up the backing plates of the 5” or 6”. So truing up the backing plate is just basic and is what’s expected when you install a new chuck.

I’m not sure what you mean by the proper tool to use the 4jw but I assume you mean a dial or test indicator to dial in the tube in the chuck. There are a lot of good vids on YouTube on how to dial in a 4jw. It’s time consuming at first but it’s basic to becoming a machinist. if you don’t have a good indicator and either a magnetic base or a mount for the tool post that is basic tooling that would make the 4jw you have work right now. Maybe your buddy can help you do your first setup with the 4jw?
 
C-Bag said:
I think Stu has a very good solution if you are doing a lot of the same size tubing. Aluminum or even pvc would work.

I have basically the same lathe, a 9x20 HF. Mine came with a 5” 3jw and 6” 4jw And the original 4” 3jw. The guy I bought it from had tricked it out according to Steve Adair’s 9x20 page. But as I used it, it became evident he had not done any of the preliminary things like truing up the backing plates of the 5” or 6”. So truing up the backing plate is just basic and is what’s expected when you install a new chuck.

I’m not sure what you mean by the proper tool to use the 4jw but I assume you mean a dial or test indicator to dial in the tube in the chuck. There are a lot of good vids on YouTube on how to dial in a 4jw. It’s time consuming at first but it’s basic to becoming a machinist. if you don’t have a good indicator and either a magnetic base or a mount for the tool post that is basic tooling that would make the 4jw you have work right now. Maybe your buddy can help you do your first setup with the 4jw?
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Dialing in a 4 jaw chuck, or any independent jaw may be time consuming the first few times you do it. There is a learning curve, but it isn't all that steep. I hated them when I first started for the reason C-Bag mentioned. It only took a few days to get comfortable with the process and do it considerably faster. Now I use the 4 jaw independent chucks almost exclusively (as opposed to a 3 jaw scroll chuck) on my Sheldon. It's easy to dial in within .001 for rough work, and not much harder to dial within .0002 for finish work.

I keep hearing guys spending the time to dial to within .0001", but I question the necessity. I can't remember the last time I needed something that precise, but then again I can't remember what I had for breakfast, and I think that was only a few hours ago. In any case I think you'll like an independent jaw chuck once you try it and see how much closer tolerances you can turn.

Keep in mind a 3 jaw scroll chuck is meant to be used when everything can be completed in one setup. The average out of round tolerance on this style chuck is in the .002" to .003" range. That essentially means a part can't be removed and reinserted with any confidence it will have the same runout as the original setup. With an independent jaw chuck the work piece can be removed as many times as you like, reinserted in any orientation, and dialed back to near 0 runout.
 
easiest way to learn to dial in a 4 jaw is with 2 chuck keys and a DTI mounted to the tool post. Takes a bit of practice but it only takes a couple of rounds of adjustment (after using the rings on the face of the chuck to get it close) to get within 0.001. I can't say I ever work to 0.0001 TIR, but 0.0005 is doable and not much harder than 0.001.

to swany - I'd get comfortable with the 4 jaw first as a) you already have it, so you're only out the cost of another chuck key and a DTI and b) you'll need it later anyway as your get more ambitious with your projects. Then you can get a 6 jaw too!
 
I fully support becoming familiar with using your 4-jaw chuck. Something I learned is to start indicating when a pair of jaws is horizontal. One of the adjusters will be at the far side of the chuck so using two keys is a bit more challenging. I only use one key (mainly because I only have one), but I make a mental note of which direction the jaw needs to move.
 
I can appreciate the problems the OP has. I had a project to complete for a friend that involved turning and parting off a number of pieces of thin walled tubing and a 3 jaw just doesn't work well - distortion and the possibility of the part camming out of the jaws. The 4 jaw doesn't work much better; still have distortion. Finally went out and got a 6 jaw Pratt Burnerd and the distortion problems went away. I can also hold Delrin/nylon parts without camming out with heavy cuts, so a 6 jaw does have its place in the shop.

So, given that a 6 jaw within his budget is available from LMS as the OP linked to, the real issue is that he doesn't know how to mount a chuck to a backplate.

@swany, mounting a chuck to a backplate is a common task a hobby guy has to eventually learn to do. There are lots of videos on Youtube about this very thing. I'm sure the guys will also be able to help you with this job. If you still have questions after that, PM me and I'll give you a hand.
 
mikey said:
So, given that a 6 jaw within his budget is available from LMS as the OP linked to, the real issue is that he doesn't know how to mount a chuck to a backplate.
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Problem is LMS says that chuck is on back order. It might show up at the end of the month and it might not. Never know with the erratic tariff situation.
 
C-Bag said:
Problem is LMS says that chuck is on back order. It might show up at the end of the month and it might not. Never know with the erratic tariff situation.
Click to expand...

What a pain! Little 6 jaws aren't plentiful on ebay, either. I guess a call to LMS might be in order.

I can tell you that a 4 jaw is not much better than a 3 jaw if distortion is the issue.
 
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