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Need to make some 1/4 30 tpi screws

Machdaddy

Plastic
Joined
Dec 21, 2017
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
 
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
 
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...:o
 
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