Longitudinal feeds and speeds for Heavy 9
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  1. #1
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    Default Longitudinal feeds and speeds for Heavy 9

    I am trying to determine the actual rotational feeds for the gear box settings on my Model O Heavy 9 lathe. The gear box chart says to multiply 3 1/4 by the threads per inch setting. But I can't get it to relate.
    If I take 3 1/4 times 64TPI setting I get 208. What does 208 represent? If I rotate the shuck one revolution I measure about .oo4" movement on the carriage?
    I'm pretty sure there is something really simple I am missing here!!!

    skipd1

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    1" divided by 64= .015625"

    that value times 3.25 REDUCTION of the apron gearing

    so really .015625 divided by 3.25= .0048

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    PM me with an email address and I'll send you a spread sheet with all the longitudinal feeds on the gear box. For the 112tpi setting, the feed is 0.0027" with the 48t stud gear (a 24t gear halves that). If you want to work it out yourself the formula is:

    feed = (1/tpi)/3.25

    I'm hoping to print some different tooth stud gears so I can cut metric threads and halve the feed rate.

    btw - my spreadsheet gives 0.0048" feed/rev for 64tpi, which matches what your DI tells you

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    damn, you fast iwananew10k

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    Or....

    the reciprocal (a common function on a hand held calculator) of 208 is .0048



    The 208 is TURNS PER INCH - an old way of expressing feeds

    Like on this 1908 L&S - the finest feed is 80 turns per inch

    ls-1908-thd-chart.jpg
    Last edited by johnoder; 11-28-2020 at 10:44 AM.

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    okay thanks


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