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IndustryArena Forum > Machine Controllers Software and Solutions > PlanetCNC > PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a Lathe
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  1. #1

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    PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a Lathe

    Hi to all.
    I have looked through all the docs I could find on the PlanetCnC site, but have not found the info I am after. I am building a small CNC Slant bed Lathe, with the spindle drive being a high speed closed loop servo (2KW), capable of accurate positioning as well - to 0.08 degrees.
    The servo drive is a step/direction drive and can do 2500RPM @ 500KHz frequency of the STEP pulse train. I am unable to find what is the max frequency that the Mk3 controller can send on step/direction output.

    I also wish to use the spindle motor as the C axis for Live Tooling operations - can the Mk3 board handle this - ie, support the motor as Spindle main motor AND C axis position servo ( not simultaneously, obviously..)
    Then in the same trend, can the Mk3 module support live tooling, eg, a high speed milling head moving in conventional lathe X/Y axis, but also in the vertical plane,ie, as in a conventional mill, while controlling the C Axis?

    Thank You!
    Regards
    Joe
    Attached Thumbnails Attached Thumbnails Spindle Motor2.jpg  

  2. #2
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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Max frequency of Mk3 is 110kHz. Use your drivers electronic gear to set steps per units that you want to use.
    I have a lathe that does everything that you describe and it works great.

  3. #3

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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Thank you for the information. Much appreciated.
    May I ask what CAM software you use to generate the G-code for your lathe? I am having some difficulty finding CAM software that does not cost a whole House of money! Most lathe CAM software that is capable of C axis control also does everything else and is very costly! I want this only for 'sophisticated' hobby use so have to be careful....Solid CAM needs Solid works ( expensive!) Smartcam is 'cloud' only, Siemens is subscription and not cheap, Fusion has now all sorts of strings attached, etc...Mastercam very expensive...

  4. #4
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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Quote Originally Posted by NoJo View Post
    Thank you for the information. Much appreciated.
    May I ask what CAM software you use to generate the G-code for your lathe? I am having some difficulty finding CAM software that does not cost a whole House of money! Most lathe CAM software that is capable of C axis control also does everything else and is very costly! I want this only for 'sophisticated' hobby use so have to be careful....Solid CAM needs Solid works ( expensive!) Smartcam is 'cloud' only, Siemens is subscription and not cheap, Fusion has now all sorts of strings attached, etc...Mastercam very expensive...

    Ecam might do as you need see here.

  5. #5

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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Thanks on the Ecam tip - I will have a look at it.

  6. #6

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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Quote Originally Posted by PlanetCNC View Post
    Max frequency of Mk3 is 110kHz. Use your drivers electronic gear to set steps per units that you want to use.
    I have a lathe that does everything that you describe and it works great.
    Good Day ( Mr PlanetCNC!)

    I would like to kindly ask if you could provide a little more information on your Lathe/PlanetCNC setup? I am very keen to use the PlanetCNC module and would like to be reasonably sure of what it's Lathe interface capabilities are.
    I will describe here again and kindly ask if you can comment on each of the functions, and if you believe it is possible - A number of people have been 'convincing' me that LinuxCNC will do all I want - after many, many hours of digging, configuring, etc, it does seem it is possible, but will still require huge effort and time - not really where I want to spend the time! In addition, the TNG software looks so much better, and the User interface is superior, in my opinion!

    So, I would love to go the PlanetCNC / TNG route!

    What I am looking to do -

    Normal X/Z 2 axis lathe - The PlanetCNC board will do that fine.

    C Axis - More Complex -
    The main spindle drive motor is ALSO the C AXIS servo positioning motor - The SAME physical motor.
    The motor is driven by STEP and DIRECTION signals, is capable of 270RPM, and can be 'electronically' geared so that for example, 50KHz input STEP pulse train = 2700RPM
    Then THAT SAME step signal (Physically the same signal) is used to position the motor, which can be set so that, for example, 1 step pule = 0.02degrees.
    The controller must therefore output a STEP signal, on the same pin, that is varied in frequency to control spindle speed, and when C axis mode is required, it outputs a STEP position signal in 0.02degree steps.
    It must also be able to do a 'HOME' on that axis before using it - use the spindle encoder Z or reference signal to zero, and then give positioning steps as need to the required angle, per the spindle encoder.

    Live Axis / Co-ordinated C axis movement :
    Also Complex:
    In that mode, I wish to for example have a live milling spindle that can move in X/Z, milling cutter in same axis as C axis, and mill flats on the shaft in the C axis by co-ordinated move of the C and X axis.

    I would appreciate very much if you could comment technically on the Board and the TNG Software ability to do this - not HOW I would do it, but if the board.SW combination is capable of this.

    Thank You
    Joe

  7. #7
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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    My setup is little different. I use servo motor/driver for spindle motor. TNG spindle output can generate steps up to 500kHz. My servo driver generates A and B "encoder" signals which I use them for synchronization. In this configuration there is no position control. All accelerations/decelerations are done by driver.
    But I can reconnect this motor/driver from spindle output to motor driver. This way I get positional control but no synchronization.

    It is not exactly what you want but it is very close.

  8. #8

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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Thank you for your reply.
    I am having difficulty in understanding, so please forgive me if I ask silly questions!

    You have a servo motor. Connected to this motor is a Servo driver electronic module. This module generates the high current drive to the servo motor.

    You have some control signals from the Planetcnc module to the servo driver -
    For SPINDLE Mode:

    What are these signals? - a variable frequency ( 0 to your indicated 500kHz??)

    What generates the A and B encoder signals - Is it the Planetcnc board signal to the servo driver, or is it FROM the servo driver to the planetCNC board. Is it from an encoder on the servo motor ? Is it an encoder on the spindle?

    Then, when you say -
    But I can reconnect this motor/driver from spindle output to motor driver.
    What does that mean -

    Forgive me, I do not understand how the various modules, boards, and signals are connected and routed in your setup.

    Joe

  9. #9
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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Spindle mode - Mk3 can generate steps/frequency for spindle up to 500kHz. Servo driver electronic module generates A and B signals which I use for synch. It is sort of simulated encoder.
    In this mode position control is not possible. If I want position control I need to connect servo driver to different connector and change couple of parameters.

  10. #10

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    Re: PlanetCnC Mk3 Controller STEP frequencies, C Axis and Live Tooling control on a L

    Thank You. I understand. Do you think it is possible to generate those two outputs from the MK3, one output = spindle steps to 500kHz, 2nd output = Servo position steps, and to 'force' outputs for each mode by means of a macro on the MK3 that is executed when a specific Gcode is executed?

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