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What collet system to use for a big lathe?

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  • What collet system to use for a big lathe?

    Some may remember that McDougall 20"x48" lathe that I bought in the spring. At some point in the future, I can see myself wanting to use collets on it. Now the big question...What collet system should I go with?

    The spindle is 3.5" x 4 tpi, MT6, 2.18" through-hole. I realize that I'll likely end up making at least an adapter to mount on the spindle....maybe even the entire collet chuck!

    I'd like to use something to pass up to 2", maybe 2 1/8", through the spindle (might as well max out the through-hole if I can) ...that's getting pretty big for most collets.

    Maybe some type of used/surplus CNC lathe chuck???

    A quick search revealed the following:
    5c isn't nearly big enough. ( 1 1/8")
    22J appears to go up to 2 1/4".
    3J goes to 1 3/4".
    16c goes up to 1 5/8".
    20c goes up to 2".

    20c or 22j look about right for size, although I have no idea what the availability of collets is like in the used market (I presume that new is $$$$$.)

    What are the opinions of the masses??????

    Andrew

  • #2
    give these folks a shout: http://www.usedtooling.com/home.php or call them @ 800-535-8331

    I have purchased used collets from them (22J I think) at a reasonable price that were in good shape.

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    • #3
      That's not really a big lathe as these things go. A 5C collet set would do the job. Larger collets would be better but they are scarcer and much more expensive. Here's a link: http://www.usshoptools.com/current_y...df/PGS_103.pdf Look ar 16C collets which go up to 1 5/8" round at $57+ each.

      I've seen collet closers large as 4" with replaceable jaw pads for bar-feed machines. Pretty specialized but it deserves mention if just for scale.

      If you want to get fancier Jacob Rubberflex collets and closers are available from time to time onrBay but at $400 and more they are expenive and you'll have to make a mount for it. .

      When I look at the threaded spindle I'd guess the top spindle speed was fairly low maybe 600 RPM. 5C collets imply workpieces 1" and smaller. 600 RPM is very much on the low side for efficient machine work for 1" workpieces; epecially if you're thinking of using carbide.
      Last edited by Forrest Addy; 06-26-2010, 08:46 PM.

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      • #4
        Originally posted by Forrest Addy
        That's not really a big lathe as these things go. A 5C collet set would do the job. Larger collets would be better but they are scarcer and much more expensive.

        I've seen them as large as 4" with replaceable jaw pads for bar feed machnes. Pretty specialzed.

        If you want to get fancier Jacob Rubberflex collets and closers are available from time to time onrBay but at $400 and more they are expenive and you'll have to make a mount for it. .

        When I look at the threaded spindle I'd guess the top spindle speed was fairly low maybe 600 RPM. 5C collets imply workpieces 1" and smaller. 600 RPM is very much on the low side for efficient machine work for 1" workpieces; epecially if you're thinking of using carbide.
        Yeah, the top speed is around 600...can't remember exactly.

        Carbide vs HSS.....I've used both...whichever works best for the job at hand.

        I don't have a project in mind that needs larger sizes...I just figured that I might as well figure it in now instead of having to get a larger set later...

        Andrew

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