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Thread: holes not center

  1. #1
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    holes not center

    i've looked around and searched, but couldn't find an answer. When i run my program, everything is correct besides the holes. The holes do not center. They are 1/16" off. I know its not my machine because every hole out of 25 are 1/16" off to the left side only. any ideas?


  2. #2
    Moderator HuFlungDung's Avatar
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    They are off relative to what? Did you machine the exterior of the part in the same setup and they are off relative to that? Or did you have an error in setting the part datum correctly?
    First you get good, then you get fast. Then grouchiness sets in.

    (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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    for instance, i was miling a square part, with a 1/16" hole in the center. I am using a 1/16" bit, and i knew it didnt look center, so i ran the prgram again, and again, and again with the same results. Then i went back into CAD and re-drew the design, added my machine lines and Gcode, and its doing it again.


  4. #4
    Community Moderator ger21's Avatar
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    Can you post a .dxf and the g-code?

    Also, what size bit are you using?
    Gerry

    Mach3 2010 Screenset
    http://home.comcast.net/~cncwoodworker/2010.html

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


  • #5
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    its a 1/16" bit.

    ( Made using CamBam - http://www.cambam.co.uk )
    ( plate 1/11/2010 9:14:00 PM )
    ( T0 : 0.062 )
    G20 G90 G64 G40
    G0 Z0.5
    ( T0 : 0.062 )
    T0 M6
    ( MOPDrill_1 )
    G17
    M3 S0
    G0 Z0.5
    G0 X2.1479 Y2.9974
    G81 Z0.125 R0.5 F30.0
    G80
    ( MOPDrill_2 )
    S0
    G0 Z0.5
    G0 X2.15 Y2.5837
    G81 Z0.125 R0.5
    G80
    ( MOPDrill_3 )
    S0
    G0 Z0.5
    G0 X2.3009 Y2.1988
    G81 Z0.125 R0.5
    G80
    ( MOPDrill_4 )
    S0
    G0 Z0.5
    G0 X4.1693 Y2.9984
    G81 Z0.125 R0.5
    G80
    ( MOPDrill_5 )
    S0
    G0 Z0.5
    G0 X4.1693 Y2.5853
    G81 Z0.125 R0.5
    G80
    ( MOPDrill_6 )
    S0
    G0 Z0.5
    G0 X4.7521 Y2.3385
    G81 Z0.125 R0.5
    G80
    ( MOPProfile_7 )
    S0
    G0 X4.8284 Y1.9692
    G1 Z0.125
    G3 F300.0 X4.8319 Y1.969 I0.0034 J0.0308
    G3 X4.8586 Y1.9728 I-0.0003 J0.0964
    G3 X4.8818 Y1.9834 I-0.0258 J0.0877
    G3 X4.9011 Y1.9997 I-0.0495 J0.0779
    G3 X4.9157 Y2.0214 I-0.0709 J0.0635
    G3 X4.9238 Y2.0458 I-0.0856 J0.0419
    G3 X4.9253 Y2.0625 I-0.0905 J0.0168
    G1 Y2.4066
    G3 Y2.4067 I-0.031 J0.0
    G3 X4.9217 Y2.4322 I-0.0927 J-0.0003
    G3 X4.9107 Y2.4566 I-0.0921 J-0.0267
    G3 X4.8943 Y2.4762 I-0.0798 J-0.0502
    G3 X4.873 Y2.4907 I-0.0616 J-0.0679
    G3 X4.8482 Y2.4987 I-0.0405 J-0.083
    G3 X4.832 Y2.5001 I-0.0167 J-0.0967
    G3 X4.8318 I-0.0001 J-0.031
    G1 X4.3819
    G2 X4.3725 Y2.5014 I0.0001 J0.0341
    G2 X4.3651 Y2.5048 I0.0083 J0.0281
    G2 X4.3588 Y2.5102 I0.0163 J0.0256
    G2 X4.3537 Y2.5178 I0.0249 J0.0222
    G2 X4.3508 Y2.5263 I0.0299 J0.0146
    G2 X4.3503 Y2.5316 I0.0292 J0.0054
    G1 Y3.1252
    G3 X4.3193 Y3.1562 I-0.031 J0.0
    G1 X4.0193
    G3 X3.9883 Y3.1252 I0.0 J-0.031
    G1 Y2.4594
    G2 X3.987 Y2.451 I-0.0308 J0.0002
    G2 X3.9832 Y2.4423 I-0.0326 J0.0094
    G2 X3.9775 Y2.4356 I-0.0273 J0.0171
    G2 X3.9707 Y2.431 I-0.0198 J0.0218
    G2 X3.9626 Y2.4284 I-0.0133 J0.0273
    G2 X3.9567 Y2.4278 I-0.0062 J0.0356
    G1 X2.3625 Y2.4284
    G2 X2.3532 Y2.4298 I0.0001 J0.0341
    G2 X2.3458 Y2.4331 I0.0083 J0.0281
    G2 X2.3395 Y2.4385 I0.0163 J0.0256
    G2 X2.3343 Y2.4461 I0.0249 J0.0222
    G2 X2.3315 Y2.4546 I0.0299 J0.0146
    G2 X2.331 Y2.46 I0.0292 J0.0054
    G1 Y3.1252
    G3 X2.3 Y3.1562 I-0.031 J0.0
    G1 X2.0
    G3 X1.969 Y3.1252 I0.0 J-0.031
    G1 Y2.0627
    G3 Y2.0626 I0.031 J0.0
    G3 X1.9727 Y2.0371 I0.0927 J0.0003
    G3 X1.9836 Y2.0127 I0.0921 J0.0267
    G3 X2.0 Y1.9931 I0.0798 J0.0502
    G3 X2.0213 Y1.9786 I0.0616 J0.0679
    G3 X2.0461 Y1.9706 I0.0405 J0.083
    G3 X2.0624 Y1.9692 I0.0167 J0.0967
    G3 X2.0625 I0.0001 J0.031
    G1 X4.8284
    G0 Z0.5
    M5
    M30


  • #6
    Community Moderator ger21's Avatar
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    What about the .dxf?
    Gerry

    Mach3 2010 Screenset
    http://home.comcast.net/~cncwoodworker/2010.html

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


  • #7
    Community Moderator ger21's Avatar
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    The g-code looks centered, if I understand you correctly. Perhaps the tool , or machine is flexing, or you have some backlash?
    Gerry

    Mach3 2010 Screenset
    http://home.comcast.net/~cncwoodworker/2010.html

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


  • #8
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    Quote Originally Posted by ger21 View Post
    The g-code looks centered, if I understand you correctly. Perhaps the tool , or machine is flexing, or you have some backlash?


    it is possible. from the naked eye, i dont see much. I will go back and run again to see if i see anything flexing. My backlash is actually pretty good, so i dont think thats it. Thanks Gerry


  • #9
    Moderator HuFlungDung's Avatar
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    Did you spot drill the hole locations to prevent drill wander?

    Is your Z axis truly perpendicular to the table? If not, and you have a significant difference in tool length between the mill and the drill, you will suffer some degree of misposition as the head travels in Z, it will displace in X and/or Y.

    It is tough to compare a backplot of your gcode to nothing, so I can't tell if the code is correct or not.
    First you get good, then you get fast. Then grouchiness sets in.

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


  • #10
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    This is what I get for a plot of the given code.
    Edit: I added the 0.062 circles for the drilled holes
    Attached Thumbnails Attached Thumbnails holes not center-program_plot.png  


  • #11
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    Quote Originally Posted by HuFlungDung View Post
    Did you spot drill the hole locations to prevent drill wander?

    Is your Z axis truly perpendicular to the table? If not, and you have a significant difference in tool length between the mill and the drill, you will suffer some degree of misposition as the head travels in Z, it will displace in X and/or Y.

    It is tough to compare a backplot of your gcode to nothing, so I can't tell if the code is correct or not.
    Quote Originally Posted by Andre' B View Post
    This is what I get for a plot of the given code.
    Edit: I added the 0.062 circles for the drilled holes


    thank you guys for the help. I actually ran the program and watched the gantry spindle spin and the actual gantry not move. I have exactly 1/16" backlash!!!


    thanks for the post, i didn't realize my holes were off center, thanks a lot!


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