View Full Version : Stepping up to a 4 jaw chuck

08-22-2003, 04:29 PM
Hi all,

I happen to own a Grizzly Lathe/Mill combo, model G4015Z, and it has a 4", 3 jaw chuck. I'd like to move 'up' to a larger, 4 jaw independent chuck for it, but Grizzly doesn't sell one that would fit it. They say that a 5" chuck is the biggest that one can use on this model and their smallest chuck that fits my bill is a 6" one. (Bummer).

Now, I've never tried putting a chuck on a lathe, so I know next to nothing about what I may need to do to get one from another maker and make it fit on my lathe.

First, what do you guys think about going with a 6" chuck, even tho' Grizzly says it's too big? (The swing is 11", so it should fit). But even at that, where would I find a decent 4 jaw indepependent chuck that can be adapted?

My lathe came with a 5" back plate and 9 1/2" face plate, so I assume that one of these two are to be used for putting on another chuck. Is that correct? (And what in the world is the OTHER one used for? :-) )

So, with that great wealth of information, can you guys please enlighten this pore ole country boy on how I can step up to the stuff you city boys use, and get a bigger, better chuck? :-)

Seriously, though, I really know next to nothing about the subject, and you guys have always been a wealth of knowledge for me.

Thanks in advance for any info.

Bruce Johnston

08-22-2003, 10:04 PM
Bison makes a good product for the money. If there is a recess in the back of the chuck, you can mount the backplate on the spindle, true it, and then CAREFULLY turn a matching flange for a close fit. I hear .005" max. clearance, closer is better. Then spot in the holes one at a time with a transfer punch. Take your time, it'll be a great addition.

08-23-2003, 03:37 AM

Grizzly is full of crap. I have a 6-1/4" four jaw universal and 3 jaw forged scroll chuck on my 7" lathe. The only thing you need to watch out for is clearance while turning. On an 11" lathe a 8" four jaw should be able to turn safely with the jaws extended the maximum amount.

NEVER, ever run the chuck with the jaws extended more than 1/2 their length past the body of the chuck! In fact, read the manual that comes with your chuck (every Bison comes with a book - BTW) and it will tell you the limit of extension of the jaws in the chuck. Never, ever, exceed that amount! Catastrophy is right around the corner if you do.

For this reason it is safer to have a larger chuck than a smaller one. You can grip larger items with greater force in a larger chuck. RPM's must be reduced with larger chucks - these limits are also in the owners manual.

So think about the largest size work you plan on doing - the chuck ideally should be larger than the maximum diameter you can turn on your machine over the cross slide.

08-23-2003, 08:14 AM
As per Thrud....

Look in the MSC www.mscdirect.com (http://www.mscdirect.com) or Travers www.travers.com (http://www.travers.com) or other catalog at the chucks and backplates. You'll want to get a chuck with a backplate to fit your lathe spindle nose. Or get a backplate blank and make your own. Bison is good stuff, reasonably priced.

When I got my Bison 3-jaw, I found the ready-made backplate to be not a particularly accurate fit on my lathe, so I ended up reworking it by boring out the threads, putting in an insert, and recutting the threads. It would have been easier to start with a blank! But the ready-made backplate would have worked okay...I was just being fanatical.

08-24-2003, 08:18 AM
I have both a Bison 5" and 6.25" 3 jaw and 6" 4 jaw independent chuck for my 10" Logan. They work well and have given me no trouble. I was concerned about the larger than recommended (by SouthBends's How to Run A Lathe) 6.25" 3 jaw, and asked on one of these machinist boards why the recommendations shouldn't be exceeded. No one could offer any reason at all, so I checked clearances and tried it. All went well and now I can chuck larger work than ever before.

08-25-2003, 06:56 PM
I've been using a six inch 4 jaw on my SB 9" for over twenty years. I can't think of any reason you shouldn't.

08-26-2003, 08:06 PM
I owned a Grizzly 4015 combo unit, the predecessor of the 4015Z, for two and a half years. The specs for the two machines were almost identical. I purchased a 6" 4 jaw chuck from J&L and mounted it on a backplate purchased from Grizzly (Part #G7773, now discontinued). It worked, however, I would agree with Grizzly on this issue. A 6" chuck on this lathe is really one size too big. The 5" chuck is a better fit. I later made two more backplates from HRS, one for a 6" 3 jaw and one for a 4" 4 jaw chuck. For some reason I could never get the 6" 3 jaw to work with out causing chatter. The same chuck worked fine when used on a larger 12 x 36 lathe (that I now own).

Unfortunately, finding a low priced 5" chuck is more difficult that the 6" variety. JTS sells perfectly nice Chinese made 6" flat backed chucks for under $60. I purchased the 4" 4 jaw also from JTS for $50 (it is now $60). All of these chucks are a nice match for a machine that costs $800. JTS and most of the other low cost vendors (Wholesale Tools, Enco, etc) do not seem to handle the 125 mm (5") chucks that are all made by the same manufacturers that make 4 and 6" varieties. You can buy a Bison 125 mm chuck (which is a fine chuck) for twice or more than the Chinese 6" variety.

With the 5" backplate that Grizzly provided with the machine it seems you are all set for a 5" chuck. Try Ebay. You may find a Bison for a decent price or perhaps another reasonably priced alternative. I notice that Lathemaster (lathemaster.com) supplies a 5" chuck (3 and 4 jaw) on their 9 x 20 sized machine (BV20BL). Maybe they would sell you a chuck.
I am sure you can locate one if you poke around.

One challenge you may run into is drilling the holes in the backplate using your 4015. I would rate the mill/drill capability of the machine as close to worthless. All is not lost, however, since you will be a better HSM for the experience and you will begin saving for a mill/drill or better.

Good luck.

[This message has been edited by sidneyt (edited 08-26-2003).]

[This message has been edited by sidneyt (edited 08-27-2003).]

08-27-2003, 12:46 AM
Maybe I was a little hard on the mill/drill part of the 4015. I learned a lot using mainly the lathe portion of machine. You can drill a hole and mill a slot with it. It's just more of a challenge to do it.

david angelo
08-27-2003, 03:02 PM
How do you tell if the chuck is too big for the lathe? Slow starting maybe? I ask cause now that I've gotten my SB9 back together I'm looking at getting a large faceplate & 4 Jaw chuck for it. It has a 6" 3 jaw chuck, is that the upper limit on size I should be thinking about?

08-28-2003, 06:03 AM

Re-read this post - it will answer your question.

Slow spin-up is often caused by the use of improper viscosity lubricants. A deviation of ISO10 can make a big difference in performance. It is not as noticable on high horsepower machines, but readily apparent on 3/4HP or less and highest spindle speeds (least torque available).

One legitimate concern is spindle load. Don't put a huge weight on a plain bearing spindle. Machines with Ball or Tapered bearing are best used for large loads. One way around this is the use of a 4-jaw independent instead of a scroll chuck - i.e. a 6-1/4" 4-jaw is about 20Lbs, and a 3-jaw is about 50Lbs! Weight goes up significantly with diameter (pi * r^2 * d * mass of steel) so 8" 3 jaws are about 85Lbs and a 10" about 160Lbs.