Set Tru 3 Jaw chucks:

Pete Wass

Pete Wass

Well-known member
It has occured to me for awhile now that a set- tru 3 jaw chuck might be just the thing for folks like me. I can think of a few situations where being able to dial things in quicker would be beneficial.

I am interested in the pro's and cons' of this type chuck please.

Thanks,

Pete
 
stool said:
pete..
i had one on the last lathe, and had one for this lathe before the lathe actually got here.

'nough said ??

i bought a mid priced one this time, and an "economical" last time.....

nothing wrong with top of the line if you can afford it
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What brand did you go with and how do you like it?
 
I have the same one, I bought it thinking it would save time etc, I used it a few times and other than having a LITTLE easier control on how tight you grab the barrel i find the 4 jaw easier and quicker to live with, I found the locking bolts needed to backed off to much to make an adjustment then when you tighten them it would move, one thing I do find it good for is trueing bolts, the bolt handle fits between the jaws.
Regards
Matt P
 
Check the runout on your existing 3 Jaw.. Insure that you can separate the backplate from the chuck. Let's say your 3Jaw has 0.0025 runout. Remove about that much from the outside of backplate. Drill and tap chuck so that 4 set screws @ 90 degrees can be used to adjust chuck.

WallyW
 
I was thinking of other situations

My thinking was to be able to have a three jaw with accuracy closer to using a set of collets. I would like to have a generally more accurate lathe. Most of the work I do with my lathe is in the 3 jaw. I wasn't just thinking about barrel work, which may be 2 or 3% of my lathe's use. A friend, who is a retired Machinist advised me to use my 4 jaw for everything. I guess to become more accustomed to centering things and to improve accuracy in everything. I'm lazier than that I guess.

Pete
 
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I find dialing in with a set-true more troublesome than a 4 jaw. The one thing one could call an advantage to a set-true, is an even jaw pressure on the work piece. Meaning you tighten the grip, then deal with adjusting.

But, I find adjusting a set-true no where near as easy, since to adjust it, you are sliding the chuck body on the backing plate, where the body is bolted to the plate. There isn't much sensitivity it in. With a 4 jaw, I can feel the pressure to the piece, I can feel the torque that goes directly to the piece when moving. To me, it's much easier.

I use a 3 jaw for pieces that get the ID and OD worked on at the same time.
 
I have a 8" Bison Set True and I absolutely love it. I can set up in a couple of minutes. You need to establish a SOP to use it and just do the same each time.
This is what I do.
Loosen the face bolts and tighten to have no play, if the dial bounces around they are too loose.
Loosen all the adjusting screws 1/4 turn.
Set up the dial on the op side of the work.
Rotate and take out almost 1/2 the error.
When down to a couple of 10 thou tighten the face bolts.
Rotate and if needed add a little more tension.
Do not fight with the screws if too tight you will eventually damage the back plate.
 
Bump this back up just to say why I waited so long to get one!

Found a really killer deal on a lightly used Bison(Poland made) 6.25" Set Tru 3-jaw chuck. This is one fabulous work holding tool that is virtually indispensable. The thing works so darn smooth and extremely easy to dial in! Won't ever go back to a standard scroll chuck! After using it a couple times, I realized how many times this would have came in handy in the past....
 
I have a Bison 3 jaw set tru chuck for my 10EE. It was set up on the initial time it was used. I'm not sure it is to be trued every time that you use it. I sure don't. I use a 4 jaw if I have to indicate the OD and ID before machining. As mentioned before, if you are doing ID and OD cutting it doesn't matter what you use, if it can be machined in one setup.
 
Wayne Shaw said:
I find dialing in with a set-true more troublesome than a 4 jaw. The one thing one could call an advantage to a set-true, is an even jaw pressure on the work piece. Meaning you tighten the grip, then deal with adjusting.

But, I find adjusting a set-true no where near as easy, since to adjust it, you are sliding the chuck body on the backing plate, where the body is bolted to the plate. There isn't much sensitivity it in. With a 4 jaw, I can feel the pressure to the piece, I can feel the torque that goes directly to the piece when moving. To me, it's much easier.

I use a 3 jaw for pieces that get the ID and OD worked on at the same time.
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AMAN.... I`ve used them.....couldn't see the advantage ......I use soft jaws on my 3 jaw.... fit to part...and when situation dictates put the 4-jaw on....
 
Speaking of 4 Jaws

I bought a used four jaw, an old USA make, cleaned it up, very good condition. I have never had it on the lathe. I so far have only held round things with this lathe. Like I said before my set true is awesome. What I have found with four jaws when evaluating some gunsmiths work is that they get tighter and tighter to the point that a mortal man like me needs a pipe to loosen them off, let alone what an oval chamber this must produce. They can also do this with a set true and this will damage the backing plate. Brute force is not needed, you might put a bit of English on it to round off that last .0001 but that's all. One needs to have a bit of self control when things start getting too tight, loosen off all screws a 1/4 turn and relax and start over.
 
Yep, I agree totally with you Ian. The more I use my set tru, the more I like it! I don't know about other adjustable chucks, but my Bison has three heavy front locking screws and the set screws are at least 1/2 in size. I think the large set screws have a big advantage over other adjustable chucks that use smaller set screws. Its extremely easy to dial down to a tenth and a much better feel than dialing in a 4 jaw. I am not bad mouthing a 4 jaw though. I like a 4 jaw and they ARE a necessity to have. I just have a 10" Chinese version that I use quite often. Its like any other tool or tooling, it has their uses. My next chuck purchase will be a quality 8" independent 4-jaw, probably another Bison.
 
Butch Lambert said:
I need a 4jaw with D1-3 mounting without an adapter plate. The plate adds 1" to the thickness.
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That's what I was debating, direct mount or adapter plate on my next 4 jaw. The 10" I have now is direct and couldn't imagine another inch dangling off the spindle...
 
4 Jaw

Sometime a four jaw is the only way to go, but not for me doing barrels! I look forward to getting mine on my lathe. Being a crip I have an engine hoist to pick the bugger up and get it mounted! Have not needed it yet but I am sure I will need it eventually.
 
I leave a 10" 4-jaw on the big lathe all the time at work. It dosnt take long to dial in using 2 chuck keys and it keeps the untrained from using lathe. I have a sky hook for changing out chucks.
 
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