Need to make some 1/4 30 tpi screws
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  1. #1
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    Default Need to make some 1/4 30 tpi screws

    My single tumbler SB 9" lathe does not offer 30 tpi which is what I need. In fact I need to make about 30 of 'em for a steam engine I'm rebuilding.Can it be done? The SB 13" @ work is also single tumbler and the big Hendey, although double tumbler won't cut 30 tpi.
    How would you approach this problem?
    Thanks

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    I’d look for a 30TPI die if it’s a one-time job.

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    1/4-3 Thread, 1" Outside Diam High Speed 39332 - MSC


    Sent from my iPhone using Tapatalk Pro

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    Quote Originally Posted by Machdaddy View Post
    My single tumbler SB 9" lathe does not offer 30 tpi which is what I need. In fact I need to make about 30 of 'em for a steam engine I'm rebuilding.Can it be done? The SB 13" @ work is also single tumbler and the big Hendey, although double tumbler won't cut 30 tpi.
    How would you approach this problem?
    Thanks
    On my Sheldon I used the 20 TPI QCGB setting and changed the drive gear from 1:1 to 1.5:1. That gave me 30TPI. In my case the stud gear is 32 and the drive gear is 32 so I changed the drive gear to 48 (1.5 to 1). You would have to apply the calc to gears in your gear train. Hope this helps.

    Edit: Same gears also gave me 27TPI using the 18TPI QCGB setting.

    Best Regards,
    Bob

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  6. #5
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    42T screw gear, with the normal 20T stud.

    Same 42T gear also lets you cut 27tpi

    Edit- I didn't catch the single tumbler and was assuming 9" workshop model A...
    Last edited by iwananew10K; 10-11-2018 at 09:44 PM.

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    This is a single tumbler machine? You can really only change the stud gear. How many teeth are on it now?

    allan

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    I would just thread mill them. Easy peasy.

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    1/4x30 die is not very common as you know. Any 30 tpi is going to hard to find.
    Here is a screen shot of where you can get such a die.
    1/4" X 3 TPI UNS


    Chet

    x30-tpi-die.jpg

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    Quote Originally Posted by moonlight machine View Post
    I would just thread mill them. Easy peasy.
    Says the guy with a CNC.

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  12. #10
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    A little less expensive, and sold for dollars, not pounds..
    1/4-3 Special Pitch Round Die, 1" Outside Diameter - High Speed Steel

    30 TPI is getting into die country for me, finer than I'd like to single point.


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