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Thread: Mach Tuning

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  1. #1
    Join Date
    Feb 2009
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    Mach Tuning

    Having trouble doing the motor tuning on my Taig setup.

    I have a G540 and the new 318oz motors.

    I tried some of the settings I found in here such as 8000 and 16000 but they werent even close.
    I am at 45000 now and it seens pretty close, but it seems so much higher than what I see other people set to it makes me think something else is wrong. Any ideas?

  2. #2
    Join Date
    Mar 2003
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    35538
    Are you talking about steps/inch? Use 2000 times the number of turns per inch of your screws. For 20tpi screws, the steps/inch would be 40,000.
    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
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    Thanks, ill give it a try.

  4. #4
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    On my Taig with Gecko540 I have my x-axis at 40.000 and Y needed 40.100.

  5. #5
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    Ok, i am at 40k for X and 40100 in Y. It seems pretty close to what it should be.

    I trying to run some simple parts out of delrin to see what I am working with.

    When I set the Jog speed to 40 percent or lower the Y axis does not move but the DROs in Mach say that Y is moving. I think that the Y and Z may not be moving some of the time while the code is running because when the part is done and I hit the return to zero button it does not go to where It should but it says it is at 0,0,0.

    Could this be a velocity or acceleration issue? Maybe I have it running too fast and it is skipping steps?

  6. #6
    Join Date
    Nov 2008
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    I seem to have noticed that Mach is sometimes funky if you change anything in Motor Tuning without exiting and restarting. I'd recommend doing that to be on the safe side.

  7. #7
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    Jun 2008
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    Quote Originally Posted by daanmuller View Post
    On my Taig with Gecko540 I have my x-axis at 40.000 and Y needed 40.100.
    Quote Originally Posted by 5artist5 View Post
    Ok, i am at 40k for X and 40100 in Y.
    ...
    5artist5, it won't make a big deal, but for now set all your axes to 40,000. Later you'll want to set your "steps per" to get the exact steps per unit for each axis (one axis might be 40,300, while another might be 39,975, it will vary from screw to screw).

  8. #8
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    Feb 2009
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    Ok, so at 40,000 what velocity and acceleration are you running?

    I'm looking for a ballpark to start in.

    Does it seem reasonable that I am running the motors too fast and or maybe too much acceleration and that is causing the motors to miss steps?

  9. #9
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    I got my acceleration at 4 and velocity at 20.

  10. #10
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    Ok, so I used 40,000 as starting points and then went into the settings tab and set the steps per unit. I did this with a dial indicator and It came out very close. (close enough for now)

    So I ran a test part and it started out ok but the y axis wouldnt advance. So I reset it and tried again and the y axis seemed to be workign but the Z axis seemed to loose steps. It kept getting deeper each pass as though it would plunge fine but then not retract fully after each plunge so that the part came out having a serious slant in it.

    There is also still a situation where If I set the slow jog below a certin threshhold the Y and Z axis' will not move but the DROs in mach3 say they are moving.


    Not sure what to try next??

  11. #11
    Join Date
    Mar 2003
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    35538
    Try increasing the pulse width. Some people width G540's seem to need a pulse width of up to 30 or 40.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  12. #12
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    Quote Originally Posted by ger21 View Post
    Try increasing the pulse width. Some people width G540's seem to need a pulse width of up to 30 or 40.
    do you mean the step pulse and direction pulse?

  13. #13
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    I also had a problem with loosing steps resulting in everything looking like a flight of stairs where it should be straight.

    I then changed too many variables around to be absolutely sure what solved it, but I think one of the following did the trick:

    a: I had too little power for my steppers and getting a 1000W step down transformator (I run an American 110V taig in Europe on a 220V powerline) instead of the 300W I was using first solved it.
    '
    b: activating 'sherline half pulse mode' in general configuration solved it. I still have that on and it sure doesnt hurt. I tried that after reading somewhere that it solved loosing steps with a Gecko G540 for someone else.

  14. #14
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    Feb 2009
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    Thanks for the suggestions guys, i'll go try these out.

    Also daanmuller, what do you have your step and direction pulses set to for your motors on the tuning page?

  15. #15
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    UPDATE

    Ok I set the step pulses to 4 on all axis and that did fix the problem of the Y and Z axis not moving when the slow jog is set below around 20 percent.

    But when I tried to run a part it was still making "stair step parts". So I turned on the Sherline half pulse mode and it seems to be working right.

    It looks like I may need to re-do the steps per unit calibration though.

    Thanks a ton all who have helped me.

  16. #16
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    Jan 2009
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    I found today that my circles still werent exactly round. So I also fiddled around with the number of steps and measuring gauges again.
    Then I thought why the heck dont I just put a pen in the spindle and draw lines on a piece of paper. Much easier to setup and very easy to measure.
    So with the motor tuning help in the setup screen I let mach move the axis 2 inches and then measured the line it drew. X was spot on with 40.000 steps but for y I was still 1/32 of inch of so Mach fixes that and now my circles are spot on.


  17. #17
    Join Date
    Feb 2009
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    I used my dial indicator and measured the movement of the table that way.
    I told mach to move the table .4" and then just watched the indicator.
    It worked out pretty good.
    Here is the interesting thing though, I then had it cut a circular pocket of .700" Diameter
    and it indeed measured .700 on my dial caliper in X and in Y. But at diagonals it is not .700".
    Going from 1:30 to 7:30 it measured .6985" and going from 10:30 to 4:30 it is .701".

    I am not going to worry about it right now though. Just wanted to share.

  18. #18
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    Nov 2007
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    I belive that is your backlash coming in to play with that description.

    Dave
    Dave->..

  19. #19
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    Feb 2007
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    You got it Dave. On mills the cutting force will tend to push the table around if there is any backlash. That is why backlash compensation (in the control, like Mach) does not really work.
    Jeff Birt

  20. #20
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    hmm, backlash ehh? I gather the only way to get rid of backlash is adjusting the nut which means sliding the screw out to expose it?

    I may just leave it for now.

    I am still getting the hang of going from 3D model to making a part that resembles that model. I think I'm gonna stick with that for now and get some parts made rather than fight for the last 2 thousandths of an inch.

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