1956 Clausing Colchester change gear problem
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  1. #1
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    Default 1956 Clausing Colchester change gear problem

    Hiya!

    13” swing Clausing Colchester Master lathe made 1956 in England. No quick change gear box. Previous owner set it up for fine feed. No spare change gears until recently when I found a 60 tooth gear. This is my lathe in my garage & I love it.

    The problem: I’d really like to thread on this lathe, but my first attempt at 20TPI came out 60TPI as shown on the optical comparator. I doubt it’s ever been set up to cut threads. The thread dial gear was upside down & not engaging the lead screw. Odd.

    Ill try to include pics of the thread chart & the previous gear arrangement for when it was set up for fine feed.

    I’m using the 30-60-100 pattern now, with no intermediate small gear next to the 60 tooth middle one.

    Any ideas?
    Attached Thumbnails Attached Thumbnails colchester-thread-chart.jpg   100_1484.jpg  

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    John: Are you thinking about putting a quick change box on? Shouldn't be hard to find one off a C-C that has been parted out. Good luck.
    JH

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    Screw pitch gauge sez the leadscrew is 6TPI. I notice there are online software calculators for change gear permutations, so somehow I've got to speed up the leadscrew feed by a factor of 3.
    I can't figure this out. I hope I'm not overlooking something really basic.

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    Quote Originally Posted by James H Clark View Post
    John: Are you thinking about putting a quick change box on? Shouldn't be hard to find one off a C-C that has been parted out. Good luck.
    JH
    That would be great, James. I was assuming I was going to have to buy some Dura-Bar & carve out some spare gears.

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    I have a 13 X 36" C-C, but the only thing I have needed was a half-nut. Called the Clausing dealer in Michigan, they wanted almost $500.00 for one. I made myself one. You might look around on the internet for someone that scrapped one out. Probably will take a while to find one. You may want to find out which models will fit your machine. Did your model only come with change gears or was a quick-change box available for it at that time. Good luck.

    JH

    Edit: Just had a thought, the Clausing dealer in Kalamazoo,Michigan may be able to tell you what models will fit your machine.

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    Quote Originally Posted by James H Clark View Post
    I have a 13 X 36" C-C, but the only thing I have needed was a half-nut. Called the Clausing dealer in Michigan, they wanted almost $500.00 for one. I made myself one. You might look around on the internet for someone that scrapped one out. Probably will take a while to find one. You may want to find out which models will fit your machine. Did your model only come with change gears or was a quick-change box available for it at that time. Good luck.

    JH

    Edit: Just had a thought, the Clausing dealer in Kalamazoo,Michigan may be able to tell you what models will fit your machine.
    Hi, James! Thanks for your help! I got it running...whoo-hoo! :-) It turned out to be a halfnut engagement carriage problem that a lot of penetrating oil fixed! The lathe never had a quick change gear box, and I strongly suspect (due to the inverted thread dial gear) that it’s never been used for threading.

    I found a math program online that simplifies what TPI you can cut based on which change gears you have. It is actually very simple & found more combinations than the lathe’s thread chart indicated.
    I have only 5 gears...20, 30, 60, 80, & 100 tooth. It turns out I can cut 20, 16, & 12 TPI with those gears using the 30 tooth stud gear in the headstock.

    Here’s the URL for the math program:

    “FOR AN IMPERIAL (inch) LEADSCREW
    TPI produced = DRIVEN/DRIVER x DRIVEN/DRIVER x LEADSCREW TPI”

    Screwcutting Programs

    Thanks again!

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    Although the leadscrew is 6 PI,the actual lead is 3 turns PI.....the thread is two start......And this is a fault with these machines,the leadscrew elements are too small /too fine and are often worn beyond use....as is the halfnut....of which there is only one .....not two as in most machines ........The weak leadscrew was remedied in later models ,but not the one sided half nut.

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    Quote Originally Posted by john.k View Post
    Although the leadscrew is 6 PI,the actual lead is 3 turns PI.....the thread is two start......And this is a fault with these machines,the leadscrew elements are too small /too fine and are often worn beyond use....as is the halfnut....of which there is only one .....not two as in most machines ........The weak leadscrew was remedied in later models ,but not the one sided half nut.
    Hi, John!

    Interesting! I just checked & this particular one’s a single start thread, as evidenced by the single thread leadout. I wish I knew more about these fine old lathes. Serial # places its manufacture in 1956, so maybe it was post the double start leadscrew engineering change?
    Attached Thumbnails Attached Thumbnails clausing-colchester-headstock.jpg  


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