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6 Jaw Lathe Chucks

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otrlt

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Hello Everyone,
I'd like to ask this question to the hard-core lathe machinist that are out there; Are 6 Jaw Lathe Chucks worth it? I'm in the process of tooling-up a lathe that I purchased last week, and I need a Buck Chuck for it. I'm very familiar with 3 jaw "Adjust-True" chucks, but I now have the opportunity to purchase a 10" Buck 6 Jaw.

Please reply with your pro's/cons.
 
6 jaws can be perfect for some jobs, but they are not a universal "better" chuck than a 3 or 4 jaw. They are made to hold thin stuff like tubing or bronze bushings lightly without distorting or crushing it.

IMO same can be said between a 4 jaw chuck and an adjustable 3 jaw chuck. Each have their advantages, but I wouldn't replace one with the other.
 
As M.B. says, there are many times when it is not possible to substitute a 6 jaw for a 3 jaw.

Sometimes a 6 jaw is just the thing. My second ever lathe project, 25 years ago, was adapting ABS to my race car and I had to substantially enlarge the spoked bore of powdered metal reluctor rings. I was very fortunate to have access to a well tooled HLV-H in the Do-It-Yourself machine shop at work, and used an available 6 jaw. By "have access", I mean it was always unlocked and there was no sign that said "Glug, Keep out!"

It was important to not distort the rings with the jaws, and not have the work piece slip during the interrupted cut. To make it more challenging, in my inexperience I started the large bore as a facing operation into the spokes rather than remove the majority of the material using a more appropriate method (hole saw would have been fine). As soon as I set this up I saw how lousy the tool geometry was. I took it slow, got lucky, and had a good outcome. I'm sure the soft material helped a lot, but also made distortion or failure a substantial risk.

If you pay attention at auctions, you can strike gold by finding a full range of pie jaws for a song. Obviously it helps to get the matched chuck. I got 4 hardinge air chuck setups and jaws that way, for about $100.

Obviously the adjust-tru won't allow you to adjust the jaws individually, though they do make independent 6 jaw chucks.

A couple years ago I scored a nice 12" 6 jaw adjust tru Buck, with an L1 back and 1300 rpm limit, for around $125. The price when new in 1966 was $562. In 2020 dollars (pre Corona!) that's $4487.
 
My Buck 8" 6 Jaw is my main chuck. I have some good 3 jaws...very seldom use them. There nothing you can do with a 3 jaw that 3 more jaws won't make better! lol

If I had a big lummox job - like turning or facing a bunch of 2" solid steel round stock pieces to loose tolerances, I'd probably use the 3 jaw for its heavy clamping ability. But otherwise, it wouldn't be worth installing.
 
Well, I'll add my .02. +1 to all pros about holding easily distorted parts. At work, we have a 6 jaw Buck. Un-experienced lathe hand was prone to cranking the snot out of it on bar stock, and subsequently broke one of the master jaws. So, con would be an inability to grasp out-of-round bar stock effectively, due to opposing jaw orientation. Think of them as 3 pairs of 180 opposite jaws. Simple solution, when clamping bars of questionable roundness, unscroll every other jaw. Now you have a 3 jaw. Two chucks for the price of one. Albiet, a more expensive one, and also should point out that when tooling up my first lathe, spent more than I wanted and ended up settling for a 3 jaw . . .
 
What? Pull a pair of jaws and chuck squares rapidly.

That's the only place I really see them being super handy.

quicker to change chucks to a 4 jaw, but I've got camlocks.. interesting though, IF you had a heavy A1-8 6 jaw say, AND two piece jaws, yea I could see taking two top jaws off...
 
Well let's see here. I have used 6-jaw chucks for a decade or more as the standard chuck on the smaller lathes at one place I worked. They are great, very good for holding thin walled work. If they are kept in good shape. If they are beat up, the scroll isn't going to keep all the jaws at the same relative distance from center, so the extra jaws won't help and may hurt on thin-walled stuff.

The nice thing about a 3-jaw is it will evenly grip even out of round work. If you need more circumferential support, pie jaws or soft jaws are available. (Helpful to have two-piece jaws and set-tru style chuck of course).

I had instances where I'd remove three of the 6 jaws on those chucks for just that reason. It can also be more difficult to get a good tight grip with extra jaws sometimes since the force is distributed between 6 jaws instead of 3. In other words, I'd rather have a 3-jaw or 4-jaw for roughing duty. One spin in the jaws can do a lot of damage with the wrong material.
 
P I A , they tend to get jammed with fine chips when you are boring, real pain to clean up, not any better than 3 jaw....Phil

"dozer no better than an excavator" haha, a slight exaggeration, but its a different tool, for different things. yes, 6 jaws work pretty well on thin wall stuff that is too big for your collets, or if you go back and forth with general chuck work and thin wall work. I happen to like them, but I like 4 jaw scroll chucks too :)

the way I see it, you need 5 or 6 chucks to cover the basics, and a 6 jaw or two is part of that mix.
 
I find the 6jaw handy for the repair work I do, just another work holding device good for some things bad for others.
There is a big difference in size of chuck, this photo shows an older Buck 6", the front piece is pretty much cut away making it weaker then the same version in a 3jaw.
For example, if a bushing is held lightly, and the speed increased above 2000rpms, the chuck will stretch enough to release the bushing.
In my experience with this chuck, and larger 6 chucks, because of the extra mechanical parts, there will be more work deflection with heavier cuts, and eventual jaw contact problems needing re-grind in the machine, but still an important tool for modifying exiting parts.
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I have 3 lathes and I keep a 6 jaw on my 13x40 permanently. I keep a 3 jaw permanently on my 18x54 and when I need a 4 jaw, I usually prefer to use my 10x40 machine. I like a 6 jaw. Yes, they are more money and they are not good for every thing, but well worth owning. I have 3 and 4 jaw chucks for all my lathes of course as well. A 6 jaw is an optional accessory chuck where 3 and 4 jaw chucks are a must have. If you get one, get one with reversible jaws. Mine is not......my only regret.
 
Found a 6 jaw set true cheap. Bought it. After running it found i could not grip stock tight enough for semi roughing. Took 3 jaws out.
 








 
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