Chuck for metal lathe question

[aggromere]

Well, now that I have my metal lathe and am using it, I have a bunch more questions. Sorry. Wish we were all in the same city so I could buy everyone a beer or something, I've been a real pain.

My question goes like this. I have a collet chuck and a six jaw self centering chuck. When I make a pen I have steps that involve both of these attachments:

1. Round on wood lathe (got that down)
2. Drill on metal lathe (using 6 jaw chuck)
3. Square ends on metal lathe (using 6 jaw chuck)
4. Put on Closed end mandrels and turn to size (on metal lathe)
5. Move mandrels to wood lathe and finish.

Now that I write it down it doesn't seem that bad, but changing chucks on a mini metal lathe is a pain. You have to use 3 nuts/bolts and there isn't much room behind the faceplate to get my fat fingers.

Is there some kind of quick mount face plate adapter so you can change out chucks fast, or does that defeat the purpose of having a metal lathe since it is for accuracy (I guess)? Or is there some kind of trick to getting those bolts behind the face plate, like a magnetic wrench or something?

 

[johnnycnc]

I just do this on my garage toy:

5 second changeover with no hassle.

 

[aggromere]

wow. I'll try that. Does that spin true like the direct mounted collet chuck?

 

[workinforwood]

Although I do not own one, I do know that you can buy small 3 and 4 jaw chucks that go into a collet closer, so you can leave the collet closer attached at all times and if you want a jaw chuck then just pop that in like any other collet. The dis advantage to this or what John shows as the opposite approach, is run-out. The further out from the head, the more run-out you get. But..a good metal lathe can be tuned very low for run-out and a pen can handle some run-out as long as it is kept to a minimum, so you do have a gnat's hair of breathing room really.

All the steps you listed can be done, and probably done faster, using just a collet chuck. You can get a drive spur, make one, or heck, I just use a straight shank dead center in a collet, mount the blank between centers like that and use the cross slide to spin a blank round. Then put blank right into another collet and drill..and heck, once you drill it, in the same collet you simply part the ends and it is square. Then spin the blank, throw a towel over the bed and apply finish. Barely even bother turning on the wood lathe any more.

 

[johnnycnc]

wow. I'll try that. Does that spin true like the direct mounted collet chuck?

Not 100%. But I'd call it 99.5...I have about .001+ or so at the collet.
That Beall has like .0002 runout inside and out if mounted properly, it's a nice
job they did on it in manufacturing.
I could shim it as I placed it in the three jaw, but for my uses..that's fine.
It's quick, easy and cheap and I can't get an internal collet closer for my lathe so it's more than acceptable to me.

 

[aggromere]

Another great idea Jeff. I use the bolt on collet chuck so I can get stock through it would one of the chucks you mention work on that or does it have to be a 3MT collet chuch to work?

 

[workinforwood]

A 3MT collet Closer is going to be easier to manage if you have a bolt-on setup, because you just plug it in the hole and you are done. But, if you have the inclanation or someone that can help you, then you can go with the 5C collet chuck at Little Machine shop. It takes some tinkering to get that mounted on a bolt style machine. My machine is bolt on too, so I bought a face plate and had a friend mount the collet chuck in the center of the face plate for me, so I never have to do any more tinkering. If I want a 3 jaw chuck, I can just pop in a 5C 3 jaw chuck rather than un bolting the entire assembly and installing the jaw chuck. The little machine shop collet chuck just uses a big allen key to pull the collets in, rather than the MT collet closers which are drawn in from behind the spindle head. It's like a big turbine mounted on the front and there's no jaws spinning in your face..I like that. Because it sticks out so far, I too have run-out, but I have it tuned as best I can and it only measures also at .001, which is more than good enough for pens. The 5C collet chuck is not only the more convenient, but it is also 1/3 the price of the MT collet closer available for my machine. Collets are cheap in that size.

 

[gr8danish]

What size is your six jaw?

If it's not too big, machine a back plate with a straight spindle for it. Then mount the chuck via a matching collet and you're all set!

***DO NOT ATTEMPT THIS WITH A LARGE HEAVY CHUCK!!! This is only a good solution for a 5" or smaller chuck. The last thing you want to do is to have a HEAVY rotating mass snap off of the spindle and come barreling towards your face!