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BlackBox - Fusion 360 - G Code

Discussion in 'Controller Boards' started by 3boysdad, May 20, 2021.

  1. 3boysdad

    3boysdad New
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    So first time user / builder of CNC (old school, bought an OX like 5 years ago, finally got it built). Long time lazer and 3d printer user. I know there's a lot going on so I'll try to be concise and provide as much info as I can.

    Anyway..designed a quick/dirty test. Followed the instructions to get the right post processor for the black box installed. Simulated the thing a few times, both in Fusion 360 and on the Black Box. Tried to run it the first time by setting the zero using the fantastic XYZ probe.. Then ran the G Code emitted by Fusion 360.

    The z axis moved up as if it were homing. Started up the motor moved down, but didn't touch the stock and started making the expected motions. But the tip of the blade was way over the stock. This behavior makes a great deal of sense as I look at the G Code, below. These numbers seem to match how I have the tool setup (see attached image below). So..I'm kind of stumped here...anyone have some ideas on what to check?
    ( Machining time : 4 min 19 sec)

    G90 G94 G17
    G21

    (When using Fusion 360 for Personal Use, the feedrate of)
    (rapid moves is reduced to match the feedrate of cutting)
    (moves, which can increase machining time. Unrestricted rapid)
    (moves are available with a Fusion 360 Subscription.)
    (onSection 0)

    (Operation 1 of 2 : 2D Pocket2)
    G54
    G53 G0 Z0
    S5000 M3
    G4 P1.8
    G0 X32.479 Y55.932
    (NOrapid)
    Z15 F1000
    (NOrapid)
    Z5
    G1 Z2.8
    <lots of moving x/y here>

    tool.png
     
  2. David the swarfer

    David the swarfer OpenBuilds Team
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    I wish you had included the entire Gcode file as an attachment.
    I believe it will show that you selected the bottom of the part as origin in Fusion, thus making all Z moves positive in the Gcode.
    But when you set Z 0 using the XYZ probe you told the machine that the top of the material is Z 0, making CUTTIING moves negative and clearance moves positive.

    So, in fusion, in the 'setup' move the origin to the top of the stock and then regenerate the Gcode.

    wcs.png
     
  3. 3boysdad

    3boysdad New
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    Thanks for the reply. I do appreciate it. I just checked that setting, sadly it was as you illustrated (photo) attached. StockOrigin.png
    Thinking I might have messed up the different height settings I checked those again for anything that would have said "start and stay 10-15mm above the stock".
     

    Attached Files:

    #3 3boysdad, May 21, 2021
    Last edited: May 22, 2021
    David the swarfer likes this.
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Include the Fusion file too, just in case David needs it too (not sure, just trying to pre-empt :) )
     
  5. sharmstr

    sharmstr OpenBuilds Team
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    Your ramp clearance is set to 2.5mm. If you want to reduce the amount of air cutting, reduce this value. Its in the Linking tab under Ramp.
     
  6. 3boysdad

    3boysdad New
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    Thanks. I'll give that a shot here when I get off work in about 8 hours...
     
  7. 3boysdad

    3boysdad New
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    So there were a few things wrong that - thanks to your nudge - got me thinking and looking. The primary among these were the bottom height setting, which needs to tell the mill how far down it will end up going. These weren't set properly - they were using the contour depth which I thought would work as I selected the bottom of the contour I wanted to cut out. I set them to the stock bottom with a offset of 3mm. I'm guessing I could have used the stock top with an offset of -3 (which appears to be the case as I look at Fusion's rendering). During the initial cut the mill wobbled a bit and even got stuck messing up the L and loosing its position. I am guess one of several things could be wrong here. First, the feed rate may be too fast. Second, the RPM might not be fast enough. And/Or third the stepper motors might not have enough current to hold/move. And finally the motion of the wheels may need some adjustments. Bottom line? I'm over this hurtle - need to get past these now. Thanks for the help again!

    BottomHeight.png
     
    #7 3boysdad, May 21, 2021
    Last edited: May 21, 2021
    sharmstr and Alex Chambers like this.
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    This Gcode cuts 6mm deep around the outside of the sign, you can see a Z-6 in the last block, so no problem there.

    This should help you understand your WCS settings
     

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