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IndustryArena Forum > Manufacturing Processes > Milling > G43 Cutter comp and G03 arc problem!
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  1. #1
    Join Date
    Jul 2020
    Posts
    1

    G43 Cutter comp and G03 arc problem!

    Hi All,

    We are about to get some new end mills for our milling machine and we need the end mill to come in from the side of the work piece and then begin it's pass along the side. I've been told that because of the high feed rate, I should program a small G03 arc between the two straight G01 moves so that it isn't as hard on the tooling or machine.

    I'm not very experienced in CNC or G code, however I've recently been able to write some programs and fix a few things G code wise. I've not used the G03 arcs before, however I didn't think they would cause me much trouble. I was wrong.


    I'm using a 32 diameter endmill and G43 Left cutter comp for the job. Whenever I try to execute the code I always get an alarm saying 'cutter comp interference' when the machine tries to execute the second G01, and also the arc doesn't seem to be being executed properly either.
    I've attached images of the path it needs to take (Blue box = work piece) (red circle = endmill) (black line = path)


    I really cant figure out why it's not working. I have the correct G43 diameter. and I have also tried adjusting the radius of the arc, I've tried using both R and IJK techniques. I can't figure it out. can anyone please help.

    code:

    G00 G90 G17 G118 X30. Y-98. M03 S500
    G43 Z280. H01
    G01 G41 X3.2 D01 F1000.
    G03 X-1.8 Y-103. R16 F500.
    G01 Y-150.
    G40
    M30

    I've tried adjusting the R value to smaller and larger values but nothing seems to work

    (I know its not the prettiest code just trying to get the arc working)
    Attached Thumbnails Attached Thumbnails Datum Cut g03 radius.jpg  

  2. #2
    Join Date
    Dec 2008
    Posts
    3110

    Re: G43 Cutter comp and G03 arc problem!

    What machine & control ?
    Does #1 offset have BOTH the H & D fields ? (I'll assume no)
    G40 cancels cutter comp
    G41 is to step LEFT of the profile (climb milling)
    G42 is to step RIGHT of the profile (conventional milling)
    G43 take up tool lenght offset.

    Are you using tool centreline paths ? (profile is already adjusted by tool radius .... D1 is set to zero)
    or
    Are you programming the actual profile ?
    ( any internal radii must be larger than the tool radius.... D1 value depends on the control.... most use the tool's actual radius)

    try
    G0 G90 G17 G118 X25. Y0.
    M03 S500
    G43 Z280. H1
    G1 Z270. F1000.
    G41 D31 X20. Y0. F500. ( using #31 set Dvalue=16.000 )
    G3 X0. Y-20. R20.
    G1 Y-50.
    G40 X20. Y-70.
    G0 Z280.
    M30

  3. #3
    Join Date
    Aug 2020
    Posts
    95

    Re: G43 Cutter comp and G03 arc problem!

    I have a similar problem. It may be related... I have an old Mazak Impulse. I have been debugging this program for a while and have finally found the offending line. If I remove setting of tool height offset (G43) it works as expected, but if I enable it, the G3 arc does unexpected things! When I run the code in g code simulators it works fine. It was originally generated by Fusion 360. When I run it on the machines visual tool path simulator on the screen, it does the wrong thing the same as what the machine does in practice.

    G90 G94 G17 G49
    G21
    G53 G0 Z0
    T1 M6
    M0
    S1380 M3
    G54
    M8
    G0 X13.052 Y-4.772
    G43 Z15. H1
    G0 Z5.
    G1 Z0.235 F175
    G18 G3 X12.417 Z-0.4 I-0.635 K0.
    G1 X8.925

    The G3 line should do a small (0.635) radius arc in the clockwise direction in the X-Z plane. If I remove the G43 line, it does exactly that. But if I have the G43 line in the arc is incorrect. If I have H1 = 50, it does a huge (about 100mm) arc in the clockwise direction (in XZ), if I have H1 set to -1, it seems to do a tiny counter clockwise arc (in XZ), so small the machine kind of just does a small sharp jerk!

    I am new to this machine and have been batting to get file generation from fusion working and upload to the machine. Then it took me three nights to work out what was going on! I only worked it out as I typed the program back in manually and by chance missed adding the G43 line! When it worked as expected I studied the difference and found the G43 line missing. When I added the G43 line it behaved exactly the same as the uploaded code.

    What do I not understand about the G43 tool height offset and why does it affect the arc? It is like the tool height is applied to the start Z coordinate and not the K coordinate. I ran some tests and proved the arcs work as per standard G code and confirmed that IJK are relative to the start point. I didn't do these tests with a tool height offset set. I guess I could do some experiments.

    Edit: I also tried this in R mode instead of IJK and got the same behavior!

  4. #4
    Join Date
    Dec 2008
    Posts
    3110

    Re: G43 Cutter comp and G03 arc problem!

    It is strange behaviour...
    Normally G43 is tool length offset only, but, there seems something is occurring in the background ie cutter comp is/has been activated

    So try this... add G40 to the safety line (top line of code).
    Single step through the program while looking at the g-code status page to see if that G40 changes to G41/G42 and also if a D address is taken up....

    I suspect that there is something not cancelled or has been incorrectly added into the toolchange macro (M6)

    Does your control have seperate fields for length & radius values for each offset (D & H fields) ?

  5. #5
    Join Date
    Aug 2020
    Posts
    95

    Re: G43 Cutter comp and G03 arc problem!

    It has me really confused. I will try some experiments over the weekend to see if I can verify what is going on. I am pretty sure it is related to the height compensation and not diameter. The radius seems to alter by about the amount set in the height offset. I did take a photo of all the modal settings at the moment after it executed the G3 line (see attached file). It was still in G40 and D is zero. The machine does have separate D and H fields.

    I will also try removing the tool change. The macro does disable cutter height compensation. I am not at home right now so don't have access to the macro file to attach. Although, generally with my testing, the tool change macro exits early as I already have the tool it wants loaded.

    I will try simplifying the program down to the bare essentials. I suspect all I will need is a G43, G1, then the G18 G3 to reproduce the problem. I will map out the arcs and coordinates for various combinations with and without tool height compensation active.

    This machine has been a real battle! It basically does not exist as far as the internet is concerned and the controller is unique to this exact machine, not used on other Mazaks. Although so far it has been consistent with standard G code. I don't have a manual for the controller . One is available for $400 but I have been toying with the idea of replacing the controller with something like a Centroid as the Mazak one has very small memory.

  6. #6
    Join Date
    Aug 2020
    Posts
    95

    Re: G43 Cutter comp and G03 arc problem!

    I have started a new thread specific to my problem as I hijacked this one!

    https://www.cnczone.com/forums/g-cod...ml#post2402820

  7. #7
    Join Date
    Jan 2005
    Posts
    15362

    Re: G43 Cutter comp and G03 arc problem!

    Quote Originally Posted by Lewis1 View Post
    Hi All,

    We are about to get some new end mills for our milling machine and we need the end mill to come in from the side of the work piece and then begin it's pass along the side. I've been told that because of the high feed rate, I should program a small G03 arc between the two straight G01 moves so that it isn't as hard on the tooling or machine.

    I'm not very experienced in CNC or G code, however I've recently been able to write some programs and fix a few things G code wise. I've not used the G03 arcs before, however I didn't think they would cause me much trouble. I was wrong.


    I'm using a 32 diameter endmill and G43 Left cutter comp for the job. Whenever I try to execute the code I always get an alarm saying 'cutter comp interference' when the machine tries to execute the second G01, and also the arc doesn't seem to be being executed properly either.
    I've attached images of the path it needs to take (Blue box = work piece) (red circle = endmill) (black line = path)


    I really cant figure out why it's not working. I have the correct G43 diameter. and I have also tried adjusting the radius of the arc, I've tried using both R and IJK techniques. I can't figure it out. can anyone please help.

    code:

    G00 G90 G17 G118 X30. Y-98. M03 S500
    G43 Z280. H01
    G01 G41 X3.2 D01 F1000.
    G03 X-1.8 Y-103. R16 F500.
    G01 Y-150.
    G40
    M30

    I've tried adjusting the R value to smaller and larger values but nothing seems to work, you would do the arc on before you applied the cutter comp if you needed the cutter comp

    (I know its not the prettiest code just trying to get the arc working)
    This is how cutter comp works, you don't need cutter comp to do a arc on arc off of your part Here is a rough Inch program with arc on/off and cutter comp
    %
    O1502
    N1G17G40G80
    T2M6
    M8
    G54
    S3450M3
    G90G0X4.63Y-1.2599
    G43Z.1H2
    G1Z-1.F20.
    G3X4.Y-.6299I-.63F12.
    G41G1X-2.435D2
    G3X-3.065Y-1.2599J-.63
    G40G0Z3.
    M9
    M5
    M30
    %
    Attached Thumbnails Attached Thumbnails Cutter Comp.PNG  
    Attached Files Attached Files
    Mactec54

  8. #8
    Join Date
    Aug 2009
    Posts
    1567

    Re: G43 Cutter comp and G03 arc problem!

    Quote Originally Posted by ashes-man View Post
    I have started a new thread specific to my problem as I hijacked this one!

    https://www.cnczone.com/forums/g-cod...ml#post2402820
    ...oh now I see this thread and where you been already. The OP Lewis was a one hit wonder anyway looks like....

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