Problem with G43 command.


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Thread: Problem with G43 command.

  1. #1
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    Default Problem with G43 command.

    Hello all,
    Lately I have a problem with a line of code with the G43.
    Line N06

    N04 T01 M06
    N05 S1000 M03
    N06 G90 G54 X-38. Y22.
    N07 G43 H01 Z25.4 M08

    When my mill hits N06 the downward motion of the Z-axis is very slow, crawl speed.
    The Z DRO counts down normally.

    I encountered this in MDI mode if I forgot to enter a G00 before entering an axis move.
    The axis called crawled to its position too , very slowly.

    Here are the lines relevant in the postprocessor BC_3xMill.MillPst

    n,rapid_move,absolute_coord,work_coord,force_x,xr, force_y,yr,p_rot, s_rot,s,spindle_on
    n,rapid_move,length_offset,d_offset,zr,coolant_on
    machining_mode

    One sees the rapid_move instruction in the two lines, but there is no G00 in the code lines. ??
    Furthermore I use the UC100 USB motion controller
    When I used the Smoothstepper I did not have this.
    I abandoned the Smoothstepper as it did not do backlash compensation.

    Any insight ?

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  2. #2
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    Default Re: Problem with G43 command.

    Quote Originally Posted by oldraven View Post
    Hello all,
    Lately I have a problem with a line of code with the G43.
    Line N06

    N04 T01 M06
    N05 S1000 M03
    N06 G90 G54 X-38. Y22.
    N07 G43 H01 Z25.4 M08

    When my mill hits N06 the downward motion of the Z-axis is very slow, crawl speed.
    The Z DRO counts down normally.

    I encountered this in MDI mode if I forgot to enter a G00 before entering an axis move.
    The axis called crawled to its position too , very slowly.

    Here are the lines relevant in the postprocessor BC_3xMill.MillPst

    n,rapid_move,absolute_coord,work_coord,force_x,xr, force_y,yr,p_rot, s_rot,s,spindle_on
    n,rapid_move,length_offset,d_offset,zr,coolant_on
    machining_mode

    One sees the rapid_move instruction in the two lines, but there is no G00 in the code lines. ??
    Furthermore I use the UC100 USB motion controller
    When I used the Smoothstepper I did not have this.
    I abandoned the Smoothstepper as it did not do backlash compensation.

    Any insight ?

    Try it like this, this is the most simple format

    N04 T01 M06
    N05 M8
    N06 G54
    N07 S1000 M03
    N08 G90G0 X-38. Y22.
    N09 G43 H01 Z25.4 M08

    Mactec54


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    Default Re: Problem with G43 command.

    You Could do what I did, Just hard code it in.

    n,"G0",absolute_coord,work_coord,force_x,xr,force_y,yr,p _rot, s_rot,s,spindle_on
    n,rapid_move,length_offset,d_offset,zr,coolant_on
    machining_mode



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    Default Re: Problem with G43 command.

    Quote Originally Posted by A1CNC View Post
    You Could do what I did, Just hard code it in.

    n,"G0",absolute_coord,work_coord,force_x,xr,force_ y,yr,p_rot, s_rot,s,spindle_on
    n,rapid_move,length_offset,d_offset,zr,coolant_on
    machining_mode
    I already did that.
    But I made a mistake , the problem is line N07 the G43 code.
    N07 G00 G43 H01 Z25.4 M08
    Did not work. The G43 still makes the head crawl downwards.

    I'll try Mactec54 's code today.



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    Default Re: Problem with G43 command.

    Quote Originally Posted by oldraven View Post
    I already did that.
    But I made a mistake , the problem is line N07 the G43 code.
    N07 G00 G43 H01 Z25.4 M08
    Did not work. The G43 still makes the head crawl downwards.

    I'll try Mactec54 's code today.
    G0 should not be used on the same line as a G43

    Mactec54


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    Default Re: Problem with G43 command.

    Well if it did not work with the change I posted and the head still creeps down 2 things are possible. (1) The control might need to see a rapid command on every line though not totally likely. (2) the section of the post you are working on might not actually be what is controlling the lines you need to change.

    Have you tried turning the debug on? This will tell you exactly what section of the post is active.

    So if you want the G0) in the line before the G43 try this,
    n,rapid_move,absolute_coord,work_coord,force_x,xr, force_y,yr,p_rot, s_rot,s,spindle_on
    n,"G00",
    n,length_offset,d_offset,zr,coolant_on
    machining_mode

    It should look like this
    N04 T01 M06
    N05 M8
    N06 G54
    N07 S1000 M03
    N08 G90G0 X-38. Y22.
    N09 G00
    N10 G43 H01 Z25.4 M08


    There could be other things that need to be updated in that post also to get it to work how you want it to, I just noticed on line 14 it is different than my post for a different machine. Can you also add the section number for the section of the post you have here? It will make it easier to help fix this.

    Last edited by A1CNC; 08-16-2017 at 08:28 AM. Reason: mactes54 suggestion GO should not be used with G43


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    Default Re: Problem with G43 command.

    Hi guys,

    I think that I have found what is going on.

    Since a couple of weeks I changed the Smoothstepper for an UC100 USB to PP.
    This to activate the Mach3 backlash control.

    Then the problem with stalling on G43 appeared.
    I have tried your advise and changed the Postprocessor.

    That did not help much. Sometimes the G43 line worked with no problem, but the second or third time the Z down stalled again.
    That got me thinking, put the Smoothstepper back in or disable the backlash control.
    As disabling the backlash was easy and quickest I did just that.

    The G43 problem was gone.
    Back to the standard BC_3x_mill post and that worked too, flawlessly .

    The backlash control made the axis jump a bit, so I suspect a spike from the stepper motor might have introduced the G43 fault.

    I will replace the Lovejoy L-50 couplings as the backlash is too much.

    Thanks for thinking with me,

    Jos Raven
    Holland
    Jos Raven PA0AMX



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    Default Re: Problem with G43 command.

    Quote Originally Posted by oldraven View Post
    Hi guys,

    I think that I have found what is going on.

    Since a couple of weeks I changed the Smoothstepper for an UC100 USB to PP.
    This to activate the Mach3 backlash control.

    Then the problem with stalling on G43 appeared.
    I have tried your advise and changed the Postprocessor.

    That did not help much. Sometimes the G43 line worked with no problem, but the second or third time the Z down stalled again.
    That got me thinking, put the Smoothstepper back in or disable the backlash control.
    As disabling the backlash was easy and quickest I did just that.

    The G43 problem was gone.
    Back to the standard BC_3x_mill post and that worked too, flawlessly .

    The backlash control made the axis jump a bit, so I suspect a spike from the stepper motor might have introduced the G43 fault.

    I will replace the Lovejoy L-50 couplings as the backlash is too much.

    Thanks for thinking with me,

    Jos Raven
    Holland
    Jos Raven PA0AMX
    Are yes backlash, will do this you did not tell us the whole story, your code was not correct also, but one thing Mach3 is good at is accepting almost anything you through at it as far as code format

    There are a few that have figured out how to use the backlash, but for most it fails badly

    Mactec54


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    Default Re: Problem with G43 command.

    Quote Originally Posted by mactec54 View Post
    Are yes backlash, will do this you did not tell us the whole story, your code was not correct also, but one thing Mach3 is good at is accepting almost anything you through at it as far as code format

    There are a few that have figured out how to use the backlash, but for most it fails badly
    The problem at the G43 is, that this line of code tells the Z-axis to move.
    The Z-axis is driven by a hefty NEMA43 stepper motor. So I imagine that this motor produces a big spike that possible is picked up by the USB cable.



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    Default Re: Problem with G43 command.

    Quote Originally Posted by oldraven View Post
    The problem at the G43 is, that this line of code tells the Z-axis to move.
    The Z-axis is driven by a hefty NEMA43 stepper motor. So I imagine that this motor produces a big spike that possible is picked up by the USB cable.
    If you are using a USB cable, it has to be a high quality cable which will protect the signals on the cable, you should also have shielded cables for your motors, with correctly terminated shields, and your motor won't interfere with any sensitive signal's

    Mactec54


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    Default Re: Problem with G43 command.

    It is definitely the backlash control.

    As I thought it could be the Z stepper that introduced the fault I set Z to zero backlash and tried again.
    No good, still the stall on G43.

    So I disabled the backlash control and made a real run with tools.

    No problem, even with the standard BC_3x_mill post . All went well.
    I have some ferrite dampers on the cables and one on the USB cable as delivered with the UC100.

    Next in the planning is to get a Renishaw MP11 probe working on the mill. I expect that to arrive by the end of the week.

    thanks



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Problem with G43 command.

Problem with G43 command.