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Thread: Deep thoughts...metric threading

  1. #21
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    Sep 2008
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    WI/IL border
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    2,192

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    Metric dies work fine without any change gears and math.

  2. #22
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    Apr 2009
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    Ashburton, near Christchurch New Zealand
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    6,649

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    I took the easy way out, metric 12x36 Chinese and imperial Drummond flat bed (c1908) lathes.

  3. #23
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    Jan 2015
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    Charlottesville, VA
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    46

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    FWIW my Smithy uses 80/63 for the metric idler for the finer threads (up to 1mm) and 64/63 for the coarser ones.

  4. #24
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    Mar 2011
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    Troy, Mi
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    129

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    Quote Originally Posted by AntonLargiader View Post
    FWIW my Smithy uses 80/63 for the metric idler for the finer threads (up to 1mm) and 64/63 for the coarser ones.
    Anton, my 127/120 combo allows me to use the threading dial. Not that it is important since it is easier to stop the motor and reverse without touching the half nut lever. I'm curious, can your setup use the threading dial and disengage the lead screw?

  5. #25
    Join Date
    Apr 2001
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    Central Ohio
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    1,080

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    Ran a Meuser for a while that had 8 different ways to cut 8 Tpi. Bet You could find one You liked.
    mark costello-Low speed steel

  6. #26
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    May 2015
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    One of the apprentices at work managed to run a die down 6" of 3/8" rod which looked like a twin start on one side, and plain rings on the other. The best drunken thread I have ever seen.
    When I was adding metric threading capability to the museum's lathe, (post #5), I included 36 and 72 teeth gears, to double or halve the input relative to the output, and it came in handy when I wanted to make a new leadscrew nut. The lathe normally would only go to 8tpi, but the leadscrew was 1" X 6 ACME. Doubling the output, I set 12tpi and got the right pitch.
    Last edited by old mart; 04-09-2019 at 09:59 AM.

  7. #27
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    Jan 2015
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    Charlottesville, VA
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    I have done so little threading I can’t say if the threading dial is useful. I tried it on a standard thread and then just backed it up after that. My impression from reading is that the dial isn’t useful for threading but I don’t know that for a fact.

    Quote Originally Posted by rickyb View Post
    Anton, my 127/120 combo allows me to use the threading dial. Not that it is important since it is easier to stop the motor and reverse without touching the half nut lever. I'm curious, can your setup use the threading dial and disengage the lead screw?

  8. #28
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    Mar 2011
    Location
    Troy, Mi
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    129

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    Quote Originally Posted by AntonLargiader View Post
    I have done so little threading I canít say if the threading dial is useful. I tried it on a standard thread and then just backed it up after that. My impression from reading is that the dial isnít useful for threading but I donít know that for a fact.
    If you cannot reverse your lathe, the threading dial is a must. No reverse means disconnecting the 1/2 nut at the end of each pass and reconnecting it when positioning the next pass. Can't get the tool/thread alignment without the threading dial.

  9. #29
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    Mar 2013
    Location
    Northwest England
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    76

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    Quote Originally Posted by rickyb View Post
    Anton, my 127/120 combo allows me to use the threading dial. Not that it is important since it is easier to stop the motor and reverse without touching the half nut lever. I'm curious, can your setup use the threading dial and disengage the lead screw?
    Ricky, I have seen this request many times and the answer is yes you can use the chasing dial on an imperial machine when cutting metric threads; so made a document of a method I was shown as an apprentice in the early 1960's -- much later I also came upon a video made by someone else so added a link to my write up -- I don't seem to be able to insert the document here but I copied and pasted it below

    If you want the document message me with your email and I will send it to you -- or anyone else interested.

    John

    Screwcutting Metric / Imperial
    2010

    This was passed to me by my apprenticeship mentor in the early 1960ís

    When screw cutting a metic thread on an imperial lathe you can use the chaser dial and disconnect the half nuts when cutting up to a shoulder by doing the following : -

    First make sure you engage the half nuts with the chasing dial on a particular number ó number 1 is best

    Then make your first cut and at the end of the cut disengage the half nuts and stop the lathe asap now retract your tool exactly as you would if it was an imperial thread ó DO NOT move the carriage ó this is very important.

    Now the thread dial will have passed number 1 so start the lathe in reverse and re-engage the half nuts on number 1 and run it back to the start point of the thread. No need to disengage here just stop the lathe, apply the second cut and start the lathe forward then repeat the above at the end of the cut.

    This allows you to thread up to a shoulder or undercut without fear of a disaster !


    Link to an excellent video demonstrating this method from the ME forum March 2019

    https://youtu.be/HXt4TWa382Q
    Knowledge withheld is knowledge lost

  10. #30
    Join Date
    Feb 2014
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    928

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    Quote Originally Posted by redgrouse View Post
    Ricky, I have seen this request many times and the answer is yes you can use the chasing dial on an imperial machine when cutting metric threads; so made a document of a method I was shown as an apprentice in the early 1960's -- much later I also came upon a video made by someone else so added a link to my write up -- I don't seem to be able to insert the document here but I copied and pasted it below

    If you want the document message me with your email and I will send it to you -- or anyone else interested.

    John

    Screwcutting Metric / Imperial
    2010

    This was passed to me by my apprenticeship mentor in the early 1960’s

    When screw cutting a metic thread on an imperial lathe you can use the chaser dial and disconnect the half nuts when cutting up to a shoulder by doing the following : -

    First make sure you engage the half nuts with the chasing dial on a particular number — number 1 is best

    Then make your first cut and at the end of the cut disengage the half nuts and stop the lathe asap now retract your tool exactly as you would if it was an imperial thread — DO NOT move the carriage — this is very important.

    Now the thread dial will have passed number 1 so start the lathe in reverse and re-engage the half nuts on number 1 and run it back to the start point of the thread. No need to disengage here just stop the lathe, apply the second cut and start the lathe forward then repeat the above at the end of the cut.

    This allows you to thread up to a shoulder or undercut without fear of a disaster !


    Link to an excellent video demonstrating this method from the ME forum March 2019

    https://youtu.be/HXt4TWa382Q
    Yep, this is the way to do it for metric threads. It makes metric threading pretty easy and painless on an imperial machine and requires just barely a little more thought than cutting imperial threads.

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