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  1. #1
    GreatBot is offline Aluminum
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    Default Metric/English Thread Chasing Dial

    I found this U.S. Patent while Googling thread chasing dials. This is for a thread chasing dial that will work with both English and metric threads on a lathe with an English lead screw. South Bend holds the patent! Has anybody seen anything like this on a South Bend (or any lathe for that matter).
    Patent # 4,218,942 (you can see if for free at www.pat2pdf.org).

    Pete

  2. #2
    Tex-VA is offline Cast Iron
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    Default Metric/English Thread Chasing Dial

    Pete, I have one, I got it from Rose when she was at Parts Works a few years back. She said they were installed on the trick-out inch/metric 10L's. I ran a thread here on making the stock thread dial indicator work with some metric threads.

    ttp://www.practicalmachinist.com/vb...d.php?t=156039

    Here's the thread dial indicator:



    Tex

  3. #3
    GreatBot is offline Aluminum
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    Tex,
    Thanks, looks quite a bit different from the patent drawing; would you have a photo of the chart on the front that you could post. If I can read it right, it looks like it was made by somebody else; the principle is probably the same I would think.
    Pete

    Pete

  4. #4
    Tex-VA is offline Cast Iron
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    Default Metric/English Thread Chasing Dial

    Pete, The Metric/English Thread Chasing Dial was made in England by the Crawford Collet Co. From what I have found they are not making it any more.
    I sent them a email to see if they had any information they would send me on the thread dial but I didn't get a response.

    http://www.crawford-collets.com/

    Here a photo of the front of the dial:



    I'm hoping to do some more work on this winter. I'll post my progress if I have any success. Tex

  5. #5
    SBLatheman's Avatar
    SBLatheman is offline Stainless
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    I was with South Bend Lathe when the IN/METRIC thread dial was designed. Only the prototype was made. It was in the 70's when the
    "metrification movement" was underway. That design was too expensive to make. Later, South Bend ( and many other manufacturers)offered the Crawford Collets thread dial as an option
    The picture that Tex-va posted is of the thread dial mounted on my Heavy Ten.
    I still have one new one left for sale ( $500 ).
    TED

  6. #6
    GreatBot is offline Aluminum
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    Tex,
    Thanks for the front pic; now I'll try to figure out what the gearing is inside.

    Pete

  7. #7
    Tex-VA is offline Cast Iron
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    Default Metric/English Thread Chasing Dial

    Hi Pete, If you haven't all ready, check out this link. I hope it works?
    Cutting Metric Threads
    Also, I have taken this thing apart and I can help you with the gear sizes. I have made some cad drawings. They are just rough sketches, but if you or anyone else wants them, let me know.
    I have only cut one size metric thread, 1.00 mm, with my 10L and metric change gears. I used the stock SB thread dial with the lead screw gear changed to 40 teeth. The details are in the earlier post. The Crawford Collet Co. thread dial has thin lead screw gears and I feel there's a chance they could get jammed in the key way in the lead screw. I want to make some new thicker gears before I mount it on the lathe. It may have been designed for a lathe with a separate drive rod. Tex

  8. #8
    GreatBot is offline Aluminum
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    Tex,
    I had seen your earlier post; in fact it was what got me thinking about a metric/English thread chasing dial.
    I would very much like to understand the gearing inside the Crawford unit; any info you have about its internals would be appreciated. I did deduce the gearing for the unit shown in the SB patent and I agree with Ted that it would have been very expensive to manufacture but it did cover a very wide range of metric threads whereas the Crawford unit is much more limited.
    At one level, my interest is somewhat academic as in 30 years of having a 10K with transposing gears, I only cut one metric thread and that was the one that you could use the standard (32 tooth worm gear) threading dial with (0.8mm pitch).
    Thanks,
    Pete

  9. #9
    Tex-VA is offline Cast Iron
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    Pete, sorry it's taken so long, I just sent you a private message. Tex

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