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Thread: Old lathe chucks, is the threaded part changeable?

  1. #1
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    Old lathe chucks, is the threaded part changeable?

    I have a 3 jaw and a 4 jaw. The 3 jaw fits my lathe spindle, but the other one doesn't. Looking at the back of them, I wonder if the threaded portion can be changed?

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    Also, what is this little thing for (that I'm pointing at with the screwdriver)? If I slide it one way, all the jaws move together, but the other way seems to allow them to move independently.

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    Glen

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    Re: Old lathe chucks, is the threaded part changeable?

    Yes I use wight lifter weights.

    Dave

    Quote Originally Posted by ArcTan View Post
    I have a 3 jaw and a 4 jaw. The 3 jaw fits my lathe spindle, but the other one doesn't. Looking at the back of them, I wonder if the threaded portion can be changed?

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    Also, what is this little thing for (that I'm pointing at with the screwdriver)? If I slide it one way, all the jaws move together, but the other way seems to allow them to move independently.

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    Re: Old lathe chucks, is the threaded part changeable?

    Yes. What lathe do you have? Do you know what spindle thread is? If your lucky you could bore out the old back plate thread and cut new threads. In some cases you can find pre-made banks that only need to be turned to size fitted to the chuck.

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by forhire View Post
    Yes. What lathe do you have? Do you know what spindle thread is? If your lucky you could bore out the old back plate thread and cut new threads. In some cases you can find pre-made banks that only need to be turned to size fitted to the chuck.
    It's a very old Worcester lathe. I can't find any markings on it other than this

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    Best I can tell the spindle is 1-5/8" with 8 threads per inch.

    I'm thinking maybe I ought to find a different four jaw independent because this one has lousy jaws. Looks like they've been welded.
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    Re: Old lathe chucks, is the threaded part changeable?

    Gee, I don't have a three jaw, but wish I did. Four jaw takes a surprising amount of time to center the work.
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by Willie B View Post
    Gee, I don't have a three jaw, but wish I did. Four jaw takes a surprising amount of time to center the work.
    That's why I want one of each

    I have a rectangular block that I need to turn, and can't use the 3 jaw for it
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    Re: Old lathe chucks, is the threaded part changeable?

    Ebay carrys a lot of backing plates. im not sure what that screw is for unless that chuck is an adjust tru or something olong thta line i have 3 and 4 jaw chucks for my lathe but its easier to just use the 4 jaw for everything than change out 90 lbs chucks
    Do not argue with an idiot. He will drag you down to his level and beat you with experience.

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by ArcTan View Post
    It's a very old Worcester lathe. I can't find any markings on it other than this

    Best I can tell the spindle is 1-5/8" with 8 threads per inch.

    I'm thinking maybe I ought to find a different four jaw independent because this one has lousy jaws. Looks like they've been welded.
    There are some photos of a 12" on vintagemachinery.org. This one uses a 1-3/4x10. 1-5/8x8 is also a common size.
    http://vintagemachinery.org/photoind....aspx?id=12117

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    Re: Old lathe chucks, is the threaded part changeable?

    If you want to make back plates to mount chucks on your lathe, it really helps to take a stub of steel and make a threaded spindle that matches your lathe spindle, this way when you are cutting the internal threads on your backplate you can check the fit as you go, without taking everything apart to check fit.
    You dont want a tight fight on the threads, or you will have a hard time taking the chucks off. The threads just pull the chuck on, it registers on the shoulder after the threads, so make that as close as identical to your lathe spindle as you can on your test stub.

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by forhire View Post
    There are some photos of a 12" on vintagemachinery.org. This one uses a 1-3/4x10. 1-5/8x8 is also a common size.
    http://vintagemachinery.org/photoind....aspx?id=12117
    Mine is more similar to this one, if not nearly identical (except for condition):

    http://vintagemachinery.org/photoind....aspx?id=18271

    Turns out mine does have 1-5/8"x8 as best as I can tell.
    Glen

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by Poleframer View Post
    If you want to make back plates to mount chucks on your lathe, it really helps to take a stub of steel and make a threaded spindle that matches your lathe spindle, this way when you are cutting the internal threads on your backplate you can check the fit as you go, without taking everything apart to check fit.
    You dont want a tight fight on the threads, or you will have a hard time taking the chucks off. The threads just pull the chuck on, it registers on the shoulder after the threads, so make that as close as identical to your lathe spindle as you can on your test stub.
    Good info, but I think I need a lot more experience before trying anything that precise!
    Glen

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    Re: Old lathe chucks, is the threaded part changeable?

    Turns out I didn't really need a four jaw chuck after all for the project at hand

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    Repairing wallowed out holes in these trunnion mount blocks

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    Glen

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    Re: Old lathe chucks, is the threaded part changeable?

    I feel much better about the job I did welding the bore horizontally on my backhoe pivot.

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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by Welder Dave View Post
    I feel much better about the job I did welding the bore horizontally on my backhoe pivot.
    Yeah, my welding was pretty ugly on this. Good news is most of it got removed on the lathe.

    What process and filler did you use? Have you gotten your drill press setup to bore it out yet?
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    Re: Old lathe chucks, is the threaded part changeable?

    Quote Originally Posted by ArcTan View Post
    Yeah, my welding was pretty ugly on this. Good news is most of it got removed on the lathe.

    What process and filler did you use? Have you gotten your drill press setup to bore it out yet?
    I figured most of your weld would be removed. I used 7018. Started with 3/32" and then went to 1/8" cause I ran out of 3/32". Once I had a decent shelf it went pretty good. The 1/8" was so much faster. I'm positive the machine I used made a huge difference, it's a 1961 SA200 Cad. Red Face. Never had to worry about the arc snuffing out or the rod sticking, etc. I ground the weld some with a plug wheel and there were a couple spots I thought might be low so preheated it again and added a little more weld. I need to enlarge the hole about 3/16" before I try the boring head in the drill press and it's pretty slow going with the plug wheel. Weld looks sound with no slag inclusions or other flaws. I need to grind some more before I move the drill press into position. I don't want to try and take too much off with the boring bar in case it dulls quick, can only take very light cuts or breaks. I'll post some pics. of my progress in the near future. I think the electronic level I bought for another reason will work great to set up the drill press. If you put in % grade it reads by .1 increments. I put it on the counter and it showed the counter was off by .4 of a degree. That should be plenty close for what I'm doing.

    https://www.empirelevel.com/torpedo-level_em105.php
    Last edited by Welder Dave; 4 Weeks Ago at 01:48 AM.

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