grbl is garbling my program

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  • February 28, 2012 at 11:26 pm #1702
    toddkrein
    Member

    I finally have the grblshield running on my arduino, connected to an old Spectralight mill (which is a Sherline mill with a nifty enclosure).

    Downloaded the latest Chimod version of the firmware, and it seems to be working fine for commands that I type in by hand.

    So, as a test, I used the GCode generator add-in for Inkscape, and generated the code for “Sofia & Annika” (to try and get the kids interested). When I run it, using the script that comes with the firmware download, I get crap.

    The “S” seems to come out fine, but then the other letters are just misshapen, tiny blobs. Running the code through the CNCSimulator, or the GWizard editor shows that it should be generating the right thing.

    Here’s a sample of the first part of the files (since I don’t know how to creat attachments. Anyone see anything obviously wrong with it?


    %
    (Header)
    (Generated by gcodetools from Inkscape.)
    (Using default header. To add your own header create file "header" in the output dir.)
    M3
    (Header end.)
    G21 (All units in mm)

    (Start cutting path id: path3020)
    (Change tool to Default tool)

    G00 Z5.000000
    G00 X35.821516 Y4.753837

    G01 Z-0.125000 F100.0(Penetrate)
    G02 X35.243153 Y4.331296 Z-0.125000 I-3.156709 J3.713725 F400.000000
    G02 X34.760425 Y4.092393 Z-0.125000 I-1.458211 J2.339308
    G02 X34.241344 Y3.949771 Z-0.125000 I-1.018893 J2.692400
    G02 X33.666264 Y3.899466 Z-0.125000 I-0.575080 J3.261956
    G02 X32.756227 Y4.040606 Z-0.125000 I-0.000000 J3.004414
    G02 X32.183494 Y4.370749 Z-0.125000 I0.468900 J1.475312
    G02 X31.803752 Y4.903241 Z-0.125000 I1.039853 J1.143213
    G02 X31.665353 Y5.575160 Z-0.125000 I1.561827 J0.671910
    G02 X31.716486 Y5.991949 Z-0.125000 I1.724068 J0.000017
    G02 X31.861032 Y6.360641 Z-0.125000 I1.488067 J-0.370716
    G02 X32.091215 Y6.684713 Z-0.125000 I1.524934 J-0.839350
    G02 X32.373663 Y6.931153 Z-0.125000 I1.151611 J-1.034800
    G02 X32.704186 Y7.116786 Z-0.125000 I1.264366 J-1.864156
    G02 X33.087488 Y7.256358 Z-0.125000 I1.081334 J-2.373530
    G02 X33.382223 Y7.320018 Z-0.125000 I0.845767 J-3.201668
    G02 X33.969432 Y7.405174 Z-0.125000 I2.131482 J-12.630820
    G03 X35.161213 Y7.591099 Z-0.125000 I-1.982944 J16.623291
    G03 X35.738833 Y7.746945 Z-0.125000 I-0.780548 J4.041342
    G03 X35.743751 Y7.950872 Z-0.125000 I-35.509017 J0.958309
    G03 X35.744336 Y8.006025 Z-0.125000 I-2.596407 J0.055152
    G03 X35.653703 Y8.571430 Z-0.125000 I-1.809079 J-0.000025
    G03 X35.463218 Y8.860396 Z-0.125000 I-0.627777 J-0.206561
    G03 X35.043695 Y9.093178 Z-0.125000 I-0.736747 J-0.833351
    G03 X34.333225 Y9.196636 Z-0.125000 I-0.710470 J-2.387755
    G03 X33.659070 Y9.117736 Z-0.125000 I-0.000000 J-2.919584
    G03 X33.299697 Y8.951356 Z-0.125000 I0.229488 J-0.966993
    G03 X33.038336 Y8.657333 Z-0.125000 I0.559366 J-0.760399
    G03 X32.806358 Y8.083184 Z-0.125000 I2.033618 J-1.155600
    G01 X31.836219 Y8.215462 Z-0.125000
    G02 X32.026319 Y8.811169 Z-0.125000 I3.074834 J-0.653042
    G02 X32.271679 Y9.221443 Z-0.125000 I1.686272 J-0.729956
    G02 X32.619085 Y9.543032 Z-0.125000 I1.206196 J-0.954586
    G02 X33.148112 Y9.811231 Z-0.125000 I1.348112 J-2.003315
    G02 X33.731445 Y9.960317 Z-0.125000 I1.066905 J-2.958755
    G02 X34.476541 Y10.017959 Z-0.125000 I0.745367 J-4.790358
    G02 X35.216491 Y9.964649 Z-0.125000 I-0.000292 J-5.166006
    G02 X35.694727 Y9.841570 Z-0.125000 I-0.327905 J-2.264773
    G02 X36.132068 Y9.621544 Z-0.125000 I-0.814983 J-2.164585
    G02 X36.383748 Y9.397832 Z-0.125000 I-0.592471 J-0.919966
    G02 X36.563434 Y9.110715 Z-0.125000 I-1.004499 J-0.828429
    G02 X36.692428 Y8.722587 Z-0.125000 I-1.727207 J-0.789537
    G02 X36.724161 Y8.467284 Z-0.125000 I-1.818064 J-0.355600
    G02 X36.742037 Y7.807566 Z-0.125000 I-12.170253 J-0.659873
    G01 X36.742037 Y6.484650 Z-0.125000
    G03 X36.767034 Y5.103238 Z-0.125000 I38.170289 J-0.000234
    G03 X36.805427 Y4.734561 Z-0.125000 I2.743118 J0.099324
    G03 X36.898959 Y4.378658 Z-0.125000 I2.116302 J0.365923
    G03 X37.056230 Y4.031743 Z-0.125000 I2.167094 J0.773329
    G01 X36.019943 Y4.031743 Z-0.125000
    G02 X35.898019 Y4.349942 Z-0.125000 I1.561732 J0.780866
    G02 X35.821507 Y4.753837 Z-0.125000 I2.450629 J0.673431
    G01 X35.821516 Y4.753837 Z-0.125000
    G00 Z5.000000

    (End cutting path id: path3020)

    (Start cutting path id: path3020)
    (Change tool to Default tool)

    G00 Z5.000000
    G00 X35.738833 Y6.969733

    G01 Z-0.125000 F100.0(Penetrate)
    G02 X35.186404 Y6.794340 Z-0.125000 I-1.368216 J3.351748 F400.000000
    G02 X34.118260 Y6.594914 Z-0.125000 I-2.867153 J12.396446
    G03 X33.513378 Y6.482145 Z-0.125000 I1.068260 J-7.408719
    G03 X33.252853 Y6.396455 Z-0.125000 I0.332406 J-1.449498
    G03 X33.024420 Y6.256516 Z-0.125000 I0.383954 J-0.883167
    G03 X32.861490 Y6.074016 Z-0.125000 I0.511021 J-0.620205
    G03 X32.759274 Y5.851231 Z-0.125000 I0.708082 J-0.459717
    G03 X32.723687 Y5.602705 Z-0.125000 I0.849901 J-0.248511
    G03 X32.801935 Y5.241192 Z-0.125000 I0.874186 J-0.000009
    G03 X33.024098 Y4.941261 Z-0.125000 I0.810554 J0.368142
    G03 X33.354985 Y4.757393 Z-0.125000 I0.586685 J0.666127
    G03 X33.903285 Y4.676678 Z-0.125000 I0.548300 J1.821953
    G03 X34.458927 Y4.744002 Z-0.125000 I0.000000 J2.326572
    G03 X34.923033 Y4.927488 Z-0.125000 I-0.441673 J1.795850
    G03 X35.313724 Y5.230622 Z-0.125000 I-0.820601 J1.460957
    G03 X35.578980 Y5.613740 Z-0.125000 I-1.075477 J1.028004
    G03 X35.687258 Y5.961617 Z-0.125000 I-1.162492 J0.552619
    G03 X35.738833 Y6.605920 Z-0.125000 I-3.999317 J0.644356
    G01 X35.738833 Y6.969733 Z-0.125000
    G00 Z5.000000

    (End cutting path id: path3020)

    (Start cutting path id: path3018)
    (Change tool to Default tool)

    G00 Z5.000000
    G00 X26.362661 Y4.031743

    G01 Z-0.125000 F100.0(Penetrate)
    G01 X26.362661 Y12.112556 Z-0.125000 F400.000000
    G01 X27.354849 Y12.112556 Z-0.125000
    G01 X27.354849 Y7.504403 Z-0.125000
    G01 X29.703025 Y9.885653 Z-0.125000
    G01 X30.987357 Y9.885653 Z-0.125000
    G01 X28.749422 Y7.713868 Z-0.125000
    G01 X31.213355 Y4.031743 Z-0.125000
    G01 X29.989659 Y4.031743 Z-0.125000
    G01 X28.054892 Y7.024851 Z-0.125000
    G01 X27.354849 Y6.352372 Z-0.125000
    G01 X27.354849 Y4.031743 Z-0.125000
    G01 X26.362661 Y4.031743 Z-0.125000
    G00 Z5.000000

    (End cutting path id: path3018)

    February 29, 2012 at 12:23 pm #1703
    alden
    Member

    As far as you know is the grblshield hardware working correctly? Do the light’s flash when they are supposed to? One possibility is that you may have current set too high and the chips are going into thermal shutdown. Are the motors firing intermittently, turning on and off or stuttering?

    If you think this is a software issue you might try posting this as an Issue at the grbl forum on github/grbl/grbl.

    – Alden

    February 29, 2012 at 10:22 pm #1704
    toddkrein
    Member

    Hmmm… I suppose that could explain why it works for the first letter, and then nothing.

    What’ the best way to test for thermal shutdown?

    March 1, 2012 at 9:05 pm #1705
    Riley
    Keymaster

    Well its fairly obvious if you touch the stepper IC very very briefly. Better solution is to get a non contact thermal gun ($25 ish) and shoot it during operations. However, what I do it just touch it and see. It will be pretty darn hot. Hot enough to cause pain so be careful. If its not a thermal issue I would 2nd aldens suggestion to post on the grbl forums.

    Also, if it is thermal shutdown there are a few things you need to ask yourself.

    1. Do I need that much current (the current pot) to make my system go? (current pots will break if you over torque them careful!)
    2. Are you using a 12v power supply? 24v will run cooler.
    3. Do you have heat sinks? / Fan?

    We sell heat sink kits – https://www.synthetos.com/webstore/index.php/accessories/heat-sinks-kit.html.

    Also, I am finishing up our case / cooler. Check it out here:
    https://www.synthetos.com/blog/grblshield-case/

    Riley

    March 13, 2012 at 5:13 am #1706
    toddkrein
    Member

    So I added the heatsinks (which I thoughtfully ordered along with the grblshield), re-tuned the current pots (by making the arm move smoothly, and minimize the buzzing it made), and it works a little better.

    took a floor fan, ran it over the board, and it ran much better.

    But ultimately, it turns out that the reason the program was failing is that the feed rate (F400) makes the motors stall. I changed it to F100, and the cutting proceeded w/o a hitch.

    March 13, 2012 at 6:11 am #1707
    alden
    Member

    Excellent. At the end of the day it’s the mechanical system that this must all be tuned to. You might take a closer look at the $4 and $5 defaults. These set the upper limit that the machine can run. Find that experimentally and set these. This will tell the software to limit inputs to these rates. That way if a Gcode file as feed rates that are too high for the board the system will still function properly – it just won’t achieve the requested feed rate in the file.

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