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Lathe Lead Screw Speed .

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  • Lathe Lead Screw Speed .

    I am going to attempt some gun Drilling. I wondered about Ideas regarding slowing down the Lead screw to a .0005 to .0008 tenths speed. I was considering disconnecting it from the Gear End and driving it with a ?? Motor from the Opposite end? You think this is Doable? I have a Old Cincinnati Tray Top Lathe. Tool room Model in Nice Shape. Thanx Mike

  • #2
    On my 9x20 lathe I simply used high reduction in the quick change gears. I don't recall the exact gearing, but the 20 tooth gear driven by the spindle drives a 127/30 which drives a 127 on the final output shaft. That drives the QCGB for a VERY large reduction of speed when in the longitudinal feed. I posted about it somewhere.
    At the end of the project, there is a profound difference between spare parts and extra parts.


    • #3
      (oops, sorry, didn't realize this was an ancient thread)...

      I did that with my SB 10K by adding a small variable-speed gearmotor on the tailstock end of the leadscrew (it's sort of a poor-man's hardinge carriage feed). The motor is bolted to the pan behind the lathe with a slotted adjustable bracket, and uses 1/2" timing belt and pulleys on the motor and end of the leadscrew. I also needed to slow down the speed rather drastically to make some high-pitched helix springs (around 1.5" pitch), but have since found that handy for other things like very slow speed crossfeed grinding. It's also easy to swap pulleys in case more adjustment is required. I'd considered changing the gearing, but wasn't practical down to the slow speeds required, and it's still synced to the spindle. Of course not being synched to the spindle will not provide perfectly accurate pitch if you're doing something like winding springs, but it's very stable once you calculate the RPM's. The other thing to be aware of is gearing that down thru the quick-change gears, will create a lot of additional force on the drivetrain, and increase the probability something will be damaged if something goes wrong. Pictures attached show it on the right end, the control with speed control pot, and fwd/rev are on the control box, and start/stop on the pendant switchbox (not
      OSHA approved no doubt).
      You'd need to calculate the speed and torque required for your lathe (I did some off-the cuff measurements with a torque meter on the end of the leadscrew, with a resistance on the carriage), but you get a lot of reduction from the leadscrew drive mechanism itself, so a large motor/gearbox probably isn't required.
      Last edited by clr2; 01-28-2020, 06:43 AM.