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Thread: 3 or 4-jaw universal chuck?

  1. #1
    Join Date
    Nov 2002
    Posts
    499

    Question 3 or 4-jaw universal chuck?

    Seen this ?? in another forum.

    Guy asked about advantages of 4-jaw self-centering scroll chuck vs 3-jaw.

    Any neat things to know other than it will center square and oct. stock?

    uute

  2. #2
    Join Date
    Apr 2003
    Location
    Outside Walnut Bottom, PA
    Posts
    126

    Post

    A 3 jaw chuck will grab stock with equal pressure on all jaws.
    A 4 jaw scroll chuck is like a 4 legged table. All 4 legs won't be on the floor if they don't match the floor.
    Every lathe should have a 4 jaw independent chuck for offsetting, rectangular stock and other odd shapes. More importantly, for "0" centering accuracy.

    bc

    BC

    If ya wannit done your way ya gotta do it yourself.

  3. #3
    Join Date
    Jan 2003
    Posts
    2,885

    Post

    I have a two jaw scroll chuck. This would be the same as removing two jaws from a four jaw scroll chuck.

    Mine is a Buck adjust-true with removeable top jaws. We make inverted vee soft jaws to hold square and even rectangular parts or other odd shaped parts.

    Very handy for production work where it's not time-efficient to dial in the parts with an independent 4 jaw.

  4. #4
    Join Date
    May 2003
    Location
    52N 122W Western Kanuckistan
    Posts
    40,418

    Post

    Ahhh... The luxury of machining being only my hobby. I can afford to take as long as I please on a setup. I use the 4 jaw independent for many jobs that you could use the 3 jaw scroll on. Since I don't have a mill I do a lot of interrupted cut work in the lathe, where I will take a piece say, 1/2x4x6 inches and true the sides and ends in the lathe. I wouldn't want to subject the lathe to the shock of this kind of cut with steel but it works just fine with aluminum which is what I use the most since with anodizing it is nearly indistructable in an outside environment. Since My main hobby is astronomy and I am building instruments that must be used out of doors for long periods I try to use materials that will not suffer corrosion. My current telescope project is all aluminum and stainless steel fasteners as well as nylatron and graphite.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  5. #5
    Join Date
    Dec 2001
    Location
    Claremont, NH
    Posts
    2,017

    Post

    Three jaws will center hex stock. I have both, and use both quite often. However, if I had to only buy two chucks, I would go three jaw, and a four jaw independent chuck, maximum versatility.

    CCBW, MAH

  6. #6

    Post

    I have a old reed-printice that came with a 3 jaw on the machine. it alway's turned about .015 out. the 3-jaw way's 120 lbs. I also have a 4-jaw which I have used ever since. wanse you get the hang of a 4-jaw for all work as far the work that I do is much more easier. In this field time is money but for a hobby works for me.

  7. #7
    Join Date
    Feb 2002
    Posts
    2,362

    Post

    HAmbone, I agree with you. I think I can set to plus minus .001 on four jaw as fast as I can take it off, store and retrieve the 3 jaw. A few things do clamp better in the 3 jaw. 3 jaw is faster for shops that start with over size stock, cut to size, and part off. A big time saver on any job is to plan on paper the sequence of cuts and trying to keep from re-mounting things for a new cut. And I do mark the work where the #1 jaw clamps but some times, for some reason things do not repeat when re-installed. Very important to make your plan and then follow it- I admit I seldom do , but, when I do, I just feel good. Proves I CAN follow instructions if I wish.
    Steve

  8. #8

    Post

    uute:
    There are 4-Jaw independents with scrolls - they allow you to set up accurately for production, yet have quick change to the next part. The best of both worlds!

    In general 6 Jaw chucks are commonly used for machining tubing as they have less tendency to distort the tubing - the result of a more even grip.

    Small 6 Jaws are used on precision sharpeners instead of collets. These little bastards cost more than the 10" chucks!

  9. #9
    Join Date
    May 2003
    Posts
    21

    Post

    I have a similar chuck Thrud. Only it is a 3 jaw scroll chuck but each jaw is also independent. Unfortunatly, the old girl is getting long in the tooth. Would like to replace it, but the only chuck like it I have found is over $2300.00! For a 6 Inch chuck! I think I have better places to spend that kind of money(or so my wife tells me).

  10. #10

    Wink

    Sunset:
    I have better places to spend that kind of money (or so my wife tells me).

    Wives can be such party poopers! As I have told RR many times, bribes are best played in a subtle manner - like roses when they least expect them, brain washing while they sleep - that sort of stuff. After a while they drop their guard - that is when you roll that 9,000lb. shaper into the garage (for example) while they least expect it!

    Bet you can tell I am not married, eh?


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