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IndustryArena Forum > CAM Software > Uncategorised CAM Discussion > new to cnc, need help with meshcam
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  1. #1
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    new to cnc, need help with meshcam

    hi everyone, im new to cnc'ing. i bought a machine a few days ago and have an stl file that i want to cut as a test to mess with settings and learn how to do this.

    my problem is that when meshcam generates the g code and i run it in mach 3 the first thing it does is smashes my spindle down on the z axis, through the backing board into the t slot table and jams it up.

    i have tried to run the code from the top and the bottom of stock and get the same result each time.

    what i am doing is:

    1) start machine and open mach 3
    2) ref all home
    3) auto zero tool
    4) move the spindle along y/x to where i want to start
    5) hit go
    6) spindle fires up and then bam! its trying to destroy my machine by driving straight down.

    can anyone look at my file and g code and tell me what i am doing wrong before i bust this machine?

    thanks
    Attached Files Attached Files

  2. #2
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    Mar 2003
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    35538

    Re: new to cnc, need help with meshcam

    6) spindle fires up and then bam! its trying to destroy my machine by driving straight down.
    What does the Mach3 Z axis DRO say when it's going down?
    The g-code is telling it to go down .063" and start cutting. Are you setting your Z zero to the top of your stock?
    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)

  3. #3
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    18

    Re: new to cnc, need help with meshcam

    Quote Originally Posted by ger21 View Post
    What does the Mach3 Z axis DRO say when it's going down?
    The g-code is telling it to go down .063" and start cutting. Are you setting your Z zero to the top of your stock?
    in meshcam i set it to the top of stock, i have also tried to set it to bottom of stock, i get the same result each time.

    as for zero...i have a metal thing that plugs into the router then i hit auto zero tool, it goes down and touches it the backs off 5mm. the metal thing is 10mm, the readout at zero in mach3 is 15.0016mm

    the person i bought the machine off used fusion 360 for a cam program, and he sent me a test file a .tap file and it cuts without issues. could it be that this machine can only run fusion g code? i have no idea really, but its going to break if i keep trying meshcam i think.

    i cannot run fusion 360 because my stl files are all in solidworks and they show up as blanks in fusion 360 (apparently a common issue)

  4. #4
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    Re: new to cnc, need help with meshcam

    You'r g-code is in inches, and it sounds like you're machine is setup in mm's?

    But that shouldn't really matter, as Mach3 will convert the code to mm's.

    So, the .063 depth should actually be cutting a 1.6mm deep.

    Bottom line, there's nothing wrong with the code, and nothing in it is telling it to plunge seep into your part.

    My guess is that something is wrong with your Mach3 setup, or the process you are using.
    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)

  5. #5
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    Re: new to cnc, need help with meshcam

    Quote Originally Posted by ger21 View Post
    You'r g-code is in inches, and it sounds like you're machine is setup in mm's?

    But that shouldn't really matter, as Mach3 will convert the code to mm's.

    So, the .063 depth should actually be cutting a 1.6mm deep.

    Bottom line, there's nothing wrong with the code, and nothing in it is telling it to plunge seep into your part.

    My guess is that something is wrong with your Mach3 setup, or the process you are using.
    it cuts fine with the test .tap file though, so it only has a fault when i use meshcam gcode.

    i tried cutting this from my metal sheet but destroyed a few hundred dollars worth of sheet so i tried cutting it into mdf board. that mdf is 36mm thick...should i set the stock size to 36mm thick? i dont think it should make a difference because i only want it to cut down 0.63 and it should know where zero is? but im out of ideas...it will break my spindle if it keeps doing it

  6. #6
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    Re: new to cnc, need help with meshcam

    Do a test run in air. Set Z0 high off the table, and watch the Z axis DRO, and see where it moves to.
    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)

  7. #7
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    Re: new to cnc, need help with meshcam

    no, i have not. do i change this line

    G0X0.0000Y0.0000Z0.1000 to G0X0.0000Y0.0000Z0.0000

    or this line

    G1A0.0000Z-0.0630F0.1 to G1A0.0000Z-0.0000F0.1

  8. #8
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    Re: new to cnc, need help with meshcam

    if i set stock to 36mm it wants to cut through 18mm and then start the part there

  9. #9
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    Re: new to cnc, need help with meshcam

    It's not the g-code telling it to cut that deep.

    The deepest your g-code cuts is .063 deep.
    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)

  10. #10
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    Re: new to cnc, need help with meshcam

    ok well that doesnt help at all...i have no idea, i know nothing about cnc but it seems like a big confusing patchwork of crap...cad/cam/machine software/hardware full of errors or incompatible, i wish i never bought it tbh

  11. #11
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    35538

    Re: new to cnc, need help with meshcam

    Without physically having access to your machine, I can't tell you why it's doing what it's doing.

    All I can tell you is that the code from MeshCAM is not causing the issue that you are seeing. It's either operator error, or some type of issue with Mach3.
    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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    Re: new to cnc, need help with meshcam

    what does "regen toolpath" do in mach3? does it rewrite gcode? should i try that?

  13. #13
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    Re: new to cnc, need help with meshcam

    It just redraws the toolpath display. It has no affect on any motion.
    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)

  14. #14
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    Re: new to cnc, need help with meshcam

    should i throw the mach3 controller card out and get something new? im lost here...i feel like taking an axe to the machine

  15. #15
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    Re: new to cnc, need help with meshcam

    Try something simple to start with.Maybe just face a block of material-even MDF.Is there a fixture offset pre-loaded that is causing the machine to act in this way?Are there G54 values anywhere on your display?There will be a simple explanation but that doesn't mean it will be easy to find.I have never used Mach 3,but I have fought a few other systems.

  16. #16
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    Re: new to cnc, need help with meshcam

    i tested this gcode on mdf and it works fine...i dont know what a g54 offset is or anything? i bought a cnc because its supposed to be easier than making things by hand but i dont think it is, its all patch work and buggy


    (CIRCLE TEST)
    (T61 D=6. CR=0. - ZMIN=-0.5 - FLAT END MILL)
    G90 G94 G91.1 G40 G49 G17
    G21
    G28 G91 Z0.
    G90

    (2D CONTOUR1)
    M5
    M9
    T61 M6
    S24000 M3
    G54
    M8
    G0 X3.851 Y1.245
    G43 Z15. H61
    Z5.
    G1 Z1. F2500.
    Z0.1
    X3.855 Y1.239 Z0.006
    X3.865 Y1.219 Z-0.085
    X3.883 Y1.188 Z-0.172
    X3.906 Y1.144 Z-0.253
    X3.935 Y1.091 Z-0.324
    X3.97 Y1.028 Z-0.385
    X4.008 Y0.957 Z-0.435
    X4.05 Y0.881 Z-0.471
    X4.094 Y0.801 Z-0.493
    X4.138 Y0.718 Z-0.5
    X4.426 Y0.191 F4000.
    G2 X4.499 Y-0.11 R0.6
    X-0.11 Y-4.499 R4.5
    X-4.499 Y0.11 R4.5
    X0.11 Y4.499 R4.5
    X4.499 Y-0.11 R4.5
    X4.411 Y-0.408 R0.6
    G1 X4.098 Y-0.92
    X4.049 Y-1.001 Z-0.493
    X4.002 Y-1.079 Z-0.471
    X3.956 Y-1.153 Z-0.435
    X3.914 Y-1.221 Z-0.385
    X3.877 Y-1.283 Z-0.324
    X3.845 Y-1.335 Z-0.253
    X3.82 Y-1.377 Z-0.172
    X3.801 Y-1.408 Z-0.085
    X3.789 Y-1.426 Z0.006
    X3.786 Y-1.433 Z0.1
    G0 Z5.
    X13.398 Y-3.644
    G1 Z1. F2500.
    Z0.1
    X13.399 Y-3.652 Z0.006
    X13.402 Y-3.673 Z-0.085
    X13.408 Y-3.709 Z-0.172
    X13.416 Y-3.757 Z-0.253
    X13.426 Y-3.818 Z-0.324
    X13.437 Y-3.888 Z-0.385
    X13.45 Y-3.968 Z-0.435
    X13.464 Y-4.054 Z-0.471
    X13.479 Y-4.144 Z-0.493
    X13.494 Y-4.237 Z-0.5
    X13.59 Y-4.829 F4000.
    G2 X13.559 Y-5.138 R0.6
    X-5.138 Y-13.559 R14.5
    X-13.559 Y5.138 R14.5
    X5.138 Y13.559 R14.5
    X14.5 Y0. R14.5
    Y-0.097 R14.5
    X13.559 Y-5.138 R14.5
    X13.378 Y-5.39 R0.6
    G1 X12.913 Y-5.769
    X12.84 Y-5.829 Z-0.493
    X12.77 Y-5.887 Z-0.471
    X12.702 Y-5.942 Z-0.435
    X12.64 Y-5.993 Z-0.385
    X12.585 Y-6.038 Z-0.324
    X12.537 Y-6.077 Z-0.253
    X12.499 Y-6.108 Z-0.172
    X12.471 Y-6.13 Z-0.085
    X12.454 Y-6.144 Z0.006
    X12.448 Y-6.149 Z0.1
    G0 Z5.
    X26.451 Y-11.521
    G1 Z1. F2500.
    Z0.1
    Y-11.528 Z0.006
    X26.453 Y-11.55 Z-0.085
    X26.455 Y-11.586 Z-0.172
    X26.458 Y-11.635 Z-0.253
    X26.462 Y-11.696 Z-0.324
    X26.467 Y-11.768 Z-0.385
    X26.472 Y-11.848 Z-0.435
    X26.478 Y-11.934 Z-0.471
    X26.484 Y-12.026 Z-0.493
    X26.49 Y-12.119 Z-0.5
    X26.53 Y-12.718 F4000.
    G2 X26.47 Y-13.023 R0.6
    X0. Y-29.5 R29.5
    X-0.067 R29.5
    X-29.5 Y0. R29.5
    X0. Y29.5 R29.5
    X29.5 Y0. R29.5
    X26.47 Y-13.023 R29.5
    X26.265 Y-13.256 R0.6
    G1 X25.767 Y-13.59
    X25.689 Y-13.642 Z-0.493
    X25.613 Y-13.693 Z-0.471
    X25.54 Y-13.742 Z-0.435
    X25.474 Y-13.786 Z-0.385
    X25.414 Y-13.826 Z-0.324
    X25.363 Y-13.86 Z-0.253
    X25.323 Y-13.888 Z-0.172
    X25.293 Y-13.908 Z-0.085
    X25.274 Y-13.92 Z0.006
    X25.268 Y-13.924 Z0.1
    G0 Z15.

    M9
    G28 G91 Z0.
    G28 X0. Y0.
    M30

  17. #17
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    Re: new to cnc, need help with meshcam

    If I had to gues, I'd say your Mach3 setup is wrong. Specifically your steps per unit, and Native Units.
    The main difference is that code is in mm's (G21), and the MeshCAM code is in inches (G20).

    G54 is the default work coordinate system, which you should already be in.

    You need to spend some time learning how Mach3 works, and how to use it.
    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)

  18. #18
    Join Date
    Jan 2018
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    16

    Re: new to cnc, need help with meshcam

    It sounds like your g code and mach3 set ups are not both in mm or in inches.The cnc must be set up to one or the other at the start of loading mach3 for the motor travel set up. you cant change g code by using select native units. under configuration tab. That is for setting motor controls for the cnc only.
    In mesh cam set zero to top of stock. use the real thickness of the stock you will use. set the mm or inches in the mesh cam tab marked define stock this should be set to what you what to work in mm or inches. mesh cam will set the g code to mm or inches by g code commands for mach3.automatically

    The tool zero must also match the units your working in i think this is the problem. you can edit the tool zero text in windows note pad the thickness of your plate is set in this code change it to the thickness of your zero plate.

    also. g70 is inches and g71 is mm. g 20 or g21 will set mach3 to the working units.look at the g code and see what mesh cam is using

    . if you zero the tool and then hit go to zero in mach3 the tool should go to the top of your stock. if it dosent the tool zero code is wrong. or there is a tool offset being used tool offsets are set in the native units you picked when loading mach3. to view hit config tab then tool table.

    In mach3 hit the tab operator than edit text bottom the screen will blink then hit tool zero button this will bring up the code its using so you can compare them. there is also a tool retract height in this code.

    sample code only for reference or comparing to yours.

    CurrentFeed = GetOemDRO(818) 'Get the current feedrate to return to later
    CurrentAbsInc = GetOemLED(48) 'Get the current G90/G91 state
    CurrentGmode = GetOemDRO(819) 'Get the current G0/G1 state


    If GetOemLed (825)=0 Then 'Check to see if the probe is already grounded or faulty
    DoOEMButton (1010) 'zero the Z axis so the probe move will start from here
    Code "G4 P3" ' this delay gives me time to get from computer to hold probe in place
    Code "G90 G31Z-4. F4" 'probing move, can set the feed rate here as well as how far to move
    While IsMoving() 'wait while it happens
    Wend
    ZProbePos = GetVar(2002) 'get the exact point the probe was hit
    Code "G0 Z" &ZProbePos 'go back to that point, always a very small amount of overrun
    While IsMoving ()
    Wend
    Call SetDro (2, .246) ' change .060 to your plate thickness and then adjust for final accuracy
    Sleep 200 'Pause for Dro to update.
    Code "G1 Z1. F50" 'put the Z retract height you want here, must be greater than the touch plate thickness
    While IsMoving ()
    Wend
    Code "(Z axis is now zeroed)" 'puts this message in the status bar
    Code "F" &CurrentFeed 'Returns to prior feed rate
    Else
    Code "(Z-Plate is grounded, check connection and try again)" 'this goes in the status bar if applicable
    End If
    If CurrentAbsInc = 0 Then 'if G91 was in effect before then return to it
    Code "G91"
    End If
    If CurrentGMode = 0 Then 'if G0 was in effect before then return to it
    Code "G0"
    End If

  19. #19
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    Re: new to cnc, need help with meshcam

    g 54 can be found on the offset tab in mach3 it will start at what ever location is in this setup hit save tool offset and see whats there if the z is set to a certain height the tool will go there to start.

  20. #20
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    Jan 2018
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    Re: new to cnc, need help with meshcam

    it looks like your cnc is set to work in g21 MM set the stock dimensions in mesh cam to MM then it should work. the machine is trying to move in inchis in the mesh cam code but the cnc is using MM. the difference between them is 25.4 units

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