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Electric lead screw on SB9C

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  • Electric lead screw on SB9C

    I have a SB9C. It has change gears and no quick change gearbox. The only time I find this to be a hinderance is when I am doing a finishing cut. I usually have the change gears set up for some common thread like 18 tpi or so. This is much too coarse for a finishing cut and it is a pain to change the gears just to make a single cut.

    So, I whipped up an electric lead screw drive this afternoon. I found a nice little 24vdc worm gear motor in the junk box. I drilled and tapped the end of the lead screw 5/16 x 18 tpi. Made a few bits and pieces and I am in business. All I need to make now is a simple pusle width modulation speed control. It runs at a nice speed as it is so that is low on the list of things to do.

    The motor and belt can be disengaged in about two seconds by loosening the bottom left bolt to remove belt tension.

    Free software for calculating bolt circles and similar: Click Here

  • #2
    That is dandy! Dang filthy bench though.

    I need to do that too. The change gears on the 7x10 are a pain. I was swaping them out 3 or 4 times the other day. I could have planed the work out better but I wanted to get one part made and tested before going to the rest of the parts.

    Great idea and fabulous craftsmanship, as usual.


    • #3
      Thats a beauty, something I have been thinking about doing for a while. Are you going to synch it to the spindle so you can use it to cut threads? You would be able to cut any kind of goofy thread you want. Thow in some limit switches and you could have auto stop and start, sweet work, great job.

      Just for info, how stout is that motor?

      James Kilroy


      • #4
        Nice Evan! Could you please post a blow-by-blow of the speed control? I'm sure a few of us could benefit!


        • #5
          I don't know when I will get around to the PWM controller for the drive. As I said, it's pretty good just the way it is. If I make one I'll document it and post it.

          Yeah. Stick in a stepper instead and a reluctor from a distributor on the spindle gear and I could be in the CNC thread making business. Don't worry, the thought had already crossed my mind.

          The bench. My excuse is that this was the last thing I did today and I was making chips all day. That's my story and I'm sticking to it.

          Oh yeah, the motor. It's got a lot of snoose. Just fine for finishing cuts although it would probably stall on a roughing cut.

          I had also already thought of a limit switch that I can mount on my micrometer stop for auto stop. I also have some nice hefty solid state relays that can handle turning off the lathe motor too. One nice feature of this little motor is that it has a special internal overun clutch that works in both directions. When power is removed the ouput stops instantly while the motor spools down. It also provides a switch closure once per rev. I have no idea what to use that for.

          [This message has been edited by Evan (edited 10-10-2005).]
          Free software for calculating bolt circles and similar: Click Here


          • #6
            Looks like a nice way to achieve the Hardinge style variable feed. Myself I am still leaning on towards a Servo type mill drive on the apron handwheel.
            Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.


            • #7

              I have been thinking about a drive also, but I am thinking along the hardinge lines.... DC drive to carriage feed.

              Also getting tired of doing fine feeds with the hand wheel. A worm drive to the handwheel drive train should allow a much finer and more even hand feed than with the hand wheel. It has the possibility of both being out of the way (parallel to bed) and also of being able to be linked with a motor for disconnectable power fine feed.

              BTW, what's wrong with that bench? Looks normal to me....

              [This message has been edited by J Tiers (edited 10-11-2005).]

              Keep eye on ball.
              Hashim Khan


              • #8
                Hello Evan,
                I used a animation motor on the leadscrew
                of my Grizzly 7x12. I have to disengage the other end of the leadscrew though.
                It turns the leadscrew at about 3 rpm and I run the spindle at about 600 rpm. The result of this makes the cut look like its chromed. I made a slotted adapter for the right end of the leadscrew and put a steel roll pin through the drive end of the animation motor. Its a simple matter to put it on or off.


                • #9
                  Doesn't the Griz have a neutral position for the lead screw? The HF does. On the rear of the head (motor side). Forward, neutral, reverse.


                  • #10
                    Hello Ken,
                    I thought that the gear train load would be a little too much for the animation motor, maybe not?. But yes there is a shifter on the back of the head from low to high range, probably neutral also.


                    • #11
                      On the mini lathe, there are 2 shifters, one for high and low, other for the leadscrew, 3 position.