4-Jaw Chuck Worth Every Penny
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Thread: 4-Jaw Chuck Worth Every Penny

  1. #1
    Happy Camper hcpookie's Avatar
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    Default 4-Jaw Chuck Worth Every Penny

    I love it! I could never get my 3-jaw chuck aligned properly after probably the first month of using it, and I always wondered if it was the spindle or the chuck... now I now! I went through three sets of jaws for the 3-jaw chuck, and couldn't ever get it to hold zero. I think the internals of the 3-jaw are soft enough that you can't calmp them tight enough without damaging the gears.

    I aligned the work in my 4-jaw and have been cranking out nice straight cuts!

    If there is one complaint, I'd say that the HF machine needs mounting studs, which if I hadn't already had some on hand, I'd be cursing LMS for not including them! Also, another 'complaint' is that the chuck key is a bit smaller than the key for the 3-jaw, which makes it a bit harder to work with. A minor complaint, I know.

    Now if only I could get all the backlash out of the lathe, I'd be happy!

    I would definitely recommend a 4-jaw chuck if anyone is having problems aligning their work. You could even align it off-center to make off-center holes.
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    Gunco Member Fal Grunt's Avatar
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    A 4 jaw is the ONLY way to center a piece to get an accurate cut. Most "good" machine shops you won't see any 3 jaws.

    What kind of lathe do you have?

    -myers

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    Gunco Veteran Toten Kopf's Avatar
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    The only "fixed" jaw chuck that I would use is a precision 6 jaw chuck. They can be pretty accurate (but will never take the place of the 4 jaw).

    I doubt that you will ever get the backlash out of the lathe.

    The closest thing to do would be to use a DRO. That way you can watch the read out as you turn your dials. Backlash won't indicate on the DRO, only actual movement.

    And I've seen them as low as $675.00 for a 2 axis lathe DRO.
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    Gunsmith Fritz's Avatar
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    A three, properly centered, has advantages in non-critical machining, like pins and things that don't need to be centered perfectly. A four is your only option when turning barrels because you have to center on the bore itself, not the outside diameter of the barrel. To my knowledge, no three or six jaw is set up for you to move the jaws independently to do this. It is a good idea to have a three and a four jaw setup, because when tolerances and centering aren't critical, the three jaw setup (or six if you are cooler than me) will save you time.

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    WHERES THE RUM Seadog's Avatar
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    Eh there. I was a military machinist for years. As I recall from my experiance we only used the 3 jaws for makeing new projects that wernt to taken out untill done.. The 4 jaws were for dialing in pre machined materials to be repaired. The 3 jaws that I used always had a bit of play like 5+++ thousanths where as a 4 jaw would get you to the thousand. My opinion is indeed the 4 jaw being far better for any precision work...Congrats on the new toy..

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    Gunco Maniac sjohnson's Avatar
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    The first lathe lesson I was taught in junior high school metal shop was that the 4 jaw was to be used for precision turning. The independent jaws allowed for centering whereas the synchronized 3 jaw would always keep a precise center from being found.
    I have a daughter. I tell her, "911 is what you dial after you're raped. 1911 is what you should have before they try."

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    Happy Camper hcpookie's Avatar
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    I don't know how I lived without this Believe it or not, I chambered a barrel with my 3-jaw and it was spot-on! Go figure. I can definitely say that a 3-jaw would be nice for turning between centers, where you don't really need precision alignment of the axis. That's about it, and frankly now that the 4-jaw is mounted, I don't think I want to worry with removing it again

    A helpful tip - Littlemachineshop has a 2-page PDF download to help with centering the jaws. I'm still learning the process, but it is pretty easy once you figure it out.
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    The "original" Boltcutter Rivet Squeezers:
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    Project Pink - the Pink and Blue AK-74:
    http://pookieweb.net/pink/pink.htm

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    No Hope For Me 1biggun's Avatar
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    Eh there. I was a military machinist for years. As I recall from my experiance we only used the 3 jaws for makeing new projects that wernt to taken out untill done.. The 4 jaws were for dialing in pre machined materials to be repaired. The 3 jaws that I used always had a bit of play like 5+++ thousanths where as a 4 jaw would get you to the thousand. My opinion is indeed the 4 jaw being far better for any precision work...Congrats on the new toy..
    well said. . i have bolth and I use the three jaw the most usualy for polishing and making stuff from raw stock. the four jaw is also the only ticket when the part is odd shaped and you want to make paet of it round.

    The cost of a good lathe is not some thing I regret. it will be worth as much when Im gone.

  9. #9
    Gunco Regular acmech's Avatar
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    I do like my 4 jaw chuck, but I've found that when the jaws are clean, my 3 jaw can consistantly chuck up a piece of drill stock with as little as .0015 6 inches from the chuck. At the machine shop at my work they use chuck heads that can be adjusted, and they use 4 and 6 jaw chucks that don't have jaws that move independently. I've sure they have 4 jaw chucks they just don't have a regular need for them. The adjustable chuck heads take care of error.

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