Six jaw chuck…

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  • #48626
    tmac1956
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    All:

    I already have a nice four jaw chuck for my Levin WW lathe, but I’m looking at purchasing a used six jaw chuck too. My question is: what can be accomplished using a six jaw chuck that cannot be accomplished using the four jaw chuck?

    Thanks!
    tmac

    #53653
    Bob Tascione
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    That’s a very good question Tom.
    The common self adjusting 6 jaw used in horology is often referred to as a bezel chuck. As the name implies it’s mostly used to hold bezels to re-groove or to do basic machining of bezels and case backs. These chucks are also good when turning parts with thin walls for both internal and external clamping of a workpiece. Having double the jaws of a three jaw and two more jaws than a 4 jaw the amount of pressure required to hold a part is distributed to these additional jaws thus reducing clamping pressure at any given clamping point which can be helpful when machining any part that may be sensitive to clamping pressure.

    Back to your question about what can be accomplished using a 6 jaw over a 4 jaw. Modifications such as soft jaws bored or turned to necessary diameters can be applied to three and 4 jaw chucks to help distribute clamping pressure and protect surfaces etc. which would effectively do as much or possibly more than a 6 jaw.

    As David has mentioned before, the 4 jaw is capable of far more accuracy than a self adjusting 3 jaw which is also true when compared to the self adjusting 6 jaw bezel chuck. There are independent 6 jaw chucks available on the market, some with micro adjustment capabilities which should give you the accuracy of a 4 jaw but my small bezel chucks for horological use are adjusted by turning a knurled outer ring. Other than shimming for slightly eccentric parts there’s no real built in independent adjusting feature in my bezel chucks. I do use a 3 jaw far more often than a 4 jaw and tend to use collets or turn between centers when close tolerances are needed. Since watch part diameters usually fall well within available collet sizes I would guess that I turn at least 50% of the time using collets, step and wax chucks, face plate, expanding plugs etc. 30% turning and truing between centers, 15% of the time with a 3 jaw, and maybe 5% of the time with a 4 jaw and bezel chuck. Of course these figures are a guesstimate and apply to watches. These usage percentages (for me) would lean much more towards the 3 and 4 jaw chucks when dealing with larger clocks unless equipped with a larger lathe using 3,4 or 5c collets. I added my preferences here just to give you an idea of what works for me. Others approach the same jobs differently with equally good results. David as you know prefers using the 4 jaw any day over a 3 jaw . I can’t argue with his reasoning for this preference as he supports it with perfect logic. The 4 jaw can be much more accurate and requires very little time for him to true the part. Soooo…. if you follow my approach then the 4 and 6 jaw usage may be fairly even with the 4 jaw usage a bit ahead of the 6 with the 6 jaw having the advantage of distributing clamping pressure out to 2 more jaws with more clamping points to help eliminate flexing which can occur when working with a thin, large diameter bezel. If you lean more towards Davids approach then I would feel the 4 jaw would prove far more valuable and useful to you than a 6 jaw except for the reasons I mention above.

    I try not to answer questions that were not even asked but I sometimes get carried away and give more info than was asked for or is necessary (as I’ve done here) :) . I added a bit extra just to give you some different perspectives. I hope it’s helpful Tom,

    Enjoy,
    Bob

    #53654
    tmac1956
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    Bob:

    I appreciate the detailed response and that is exactly what I needed. I am currently trying to tool up a mini mill drill and the money I can save by not buying something that I don’t need (at least at the moment) always helps (limited resources you know).

    Thanks!
    tmac

    #53655
    david pierce
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    Tom,
    Both lathe and milling machine accessories can be expensive and can easily exceed the cost of the basic machines. Keep in mind that you do not have to purchase everything at once. Some items require a great deal of quality and precision such as a Jacobs ball bearing drill chuck. Other items like a clamping set will work the way they are supposed to regardless of their quality. You will find as you do more machine work that you will develop a feel for using tools and accessories. There is no hurry so wait until the stuff comes on sale before you buy it.
    david

    #53656
    tmac1956
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    @david pierce wrote:

    Tom,
    Both lathe and milling machine accessories can be expensive and can easily exceed the cost of the basic machines. Keep in mind that you do not have to purchase everything at once. Some items require a great deal of quality and precision such as a Jacobs ball bearing drill chuck. Other items like a clamping set will work the way they are supposed to regardless of their quality. You will find as you do more machine work that you will develop a feel for using tools and accessories. There is no hurry so wait until the stuff comes on sale before you buy it.
    david

    David:

    I appreciate the advice. I do get a little ahead of myself at times.

    Many thanks!
    Tom

    #53657
    david pierce
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    • Topics Started: 90
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    Tom,
    If you do not already have one of these chucks you can always make a fixture to hold the bezel and hold the part in with friction and some shellac,
    david

    #53658
    david pierce
    Participant
    • Topics Started: 90
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    Tom,
    Did you ever purchase a small dial indicator and magnetic base. This will be needed to center your work in the four jaw chuck. I have not looked but I am sure that there are Youtube videos showing how to do this. Once you get the technique down you will be able to get the work centered very quickly.
    david

    #53659
    tmac1956
    Participant
    • Topics Started: 171
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    @david pierce wrote:

    Tom,
    Did you ever purchase a small dial indicator and magnetic base. This will be needed to center your work in the four jaw chuck. I have not looked but I am sure that there are Youtube videos showing how to do this. Once you get the technique down you will be able to get the work centered very quickly.
    david

    david:

    I have on order the one (plus the stand) that you recommended from Enco.

    Thanks!
    tmac

    #53660
    tmac1956
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    daivd:

    I found a good video on how to center the four jaw chuck.

    http://www.youtube.com/watch?v=X_zYTdiSUXQ

    Thanks for telling about that!
    Tom

    #53661
    david pierce
    Participant
    • Topics Started: 90
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    Tom,
    Harbor Freight has some machinist tools. Some of them such as the digital dial caliper, magnetic base, and dial indicators are ok and they are inexpensive.
    david

    #53662
    tmac1956
    Participant
    • Topics Started: 171
    • Total Posts: 1259

    @david pierce wrote:

    Tom,
    Harbor Freight has some machinist tools. Some of them such as the digital dial caliper, magnetic base, and dial indicators are ok and they are inexpensive.
    david

    david:

    I have those on order from ENCO. I did find out that we have a Harbor Freight store in our town and went over for a visit during a recent sale. They have some good deals especially on the heavy stuff. Unfortunately, the store is on the small side and they don’t carry the small tool selection offered on the web. Mostly just General Tool junk. However, they do match the prices online and you don’t have to pay the shipping that you do online.

    I’d never heard of them until you mentioned them. The place was packed!

    Thanks!
    tmac

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tmac1956Six jaw chuck…