No announcement yet.

Clough42 ELS on PM1236T

  • Filter
  • Time
  • Show
Clear All
new posts

  • Clough42 ELS on PM1236T

    Since Kevin implemented separate ratios for lathes with separate feed screws, I decided to look at the source code, look at the gear ratios involved, and decided upon the fact if the gear box is set to B1, the leadscrew rotates 1:1 with the spindle. It has an 8 TPI screw, so engaging the half nuts, verified the carriage moved .125" with 1 full revolution.
    A gear box setting of C1 is 2:1, verified with 2 full revolutions equaling .125. I figured I would run the lathe at C1, so the servo drive has a nice 2:1 torque advantage driving the input spindle to the gear box. Yes, I am going to keep the gear box, only removing the gears on the side that drive the gearbox from the spindle at a fixed 1:1 ratio.

    The feed screw however does not have a nice gear ratio to work with. With some ratio math I came up with a decimal number to set for the micro-stepping to act as a division factor for the servo drive. I am thankful that Kevin decided to use floating point processing with his ELS.
    Anyhow, here is the pertinent configuration I will try out first.
    Sorry to say that I am going on another work trip shortly so I will not be able to implement and test any of this until a later date.
    //================================================== ==============================
    // Define the number of steps and microsteps for your stepper motor, the pin
    // polarity of the driver, and whether to use additional features, like servo
    // alarm feedback.
    // NOTE: If you are using a servo drive with something other than a 1:1 drive
    // ratio, you can use the STEPPER_MICROSTEPS to compensate. For example, if you
    // have a servo configured for 1000 steps/revolution and it drives the leadscrew
    // through a 3:1 reduction, you can set STEPPER_RESOLUTION to 1000 and
    //================================================== ==============================
    // Steps and microsteps
    //PM1236T lathe, B1 gives 1:1 Spindle to Leadscrew rotation, C1 gives 2:1. Microsteps set to 2 to compensate for the 2:1.
    #define STEPPER_RESOLUTION 1000
    // Separate step and microstep settings for feed rates. Redefine these if your
    // lathe has a separate feed drive train with a different ratio.
    // PM1236T set to C1 moves the carriage .01474 instead of .0625 from the feed screw, giving .47168 for microsteps/division factor
    #define STEPPER_MICROSTEPS_FEED 0.47168

  • #2
    Nothing like getting parts in to play with on the day you have to leave. When I get back I'll get the CNC mill going and machine out the front panel cover of the box for the interface and mount the integrated servo/drive. It's an actual servo, not a closed loop stepper.

    Click image for larger version  Name:	A7DEE295-0BAC-4F8F-BFB1-E5593BB572D4.jpeg Views:	2 Size:	2.36 MB ID:	1964545‚ÄčClick image for larger version  Name:	6527393D-9171-43A6-A8E5-26BCF3DB29C0.jpeg Views:	2 Size:	1.08 MB ID:	1964544
    Last edited by RB211; 10-04-2021, 01:44 PM.


    • #3
      Good for you and James at Clough42 ( YouTube) is a remarkable guy!! Found his channel 6 months ago. Cuz of him, I loaded Fusion 360 on the PC. Nice CAD CAM software. Hope you have an easy time setting it up! Let us know your ups....and downs. Thought about doing the same, but most i do with a floating Die in tailstock. My gear box sits @ 20 TPI. That's 1/4-20 7/16-20. 1/2-20. 5/8-20. 1.00-20. Being a home shop, I can just pick one and thread away if i need too. Congrats on the upgrade.