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Fusion 360 post to GRBL has Z inversion of multi depth cuts

Discussion in 'CAM' started by sjhilton, Feb 15, 2023.

  1. sjhilton

    sjhilton New
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    This is a recent problem from what I can remember of past Fusion posts for the GRBL ...

    The post shows that the Z depth is inverted (the first cut is at the bottom most level and subsequent levels are raised above). A photo might show what I mean... upload_2023-2-15_18-10-25.png

    As you can see in the Fusion Simulation, the cutout is done from the bottom most and the 2nd and 3rd levels are higher up. I have not found anyone in Google searches having this problem. Wondering if I mistakenly changed something???

    My CNC is a working plate maker with front left X0 Y0. My Z axis homes to the top (positive) and I set the initial Z0 to the top of stock so all cuts occur at negative values.

    I have checked/rechecked the settings, tried various GRBL posts, ate/slept/prayed.

    Can anyone school me on what I might have done or ~done? Thanks.

    Steve
     
  2. sharmstr

    sharmstr OpenBuilds Team
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    The post has nothing to do with it. What you are seeing happens before any post processor is utilized. Post your fusion file here and we'll have a look at it.
     
  3. sjhilton

    sjhilton New
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    OK. I exported this from Fusion. Thanks for helping.
     

    Attached Files:

  4. sharmstr

    sharmstr OpenBuilds Team
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    It looks fine to me. I think you might be confused by the simulation. Try changing the toolpath mode to "Toolpath before position". That will show you were the tool has already cut. In your image above you have it set to "Toolpath after" which shows were its going to cut. Which, again, looks correct to me.

    Also, I did notice that your setup doesnt have the axis specified. Its good practice to do that.
     
  5. sharmstr

    sharmstr OpenBuilds Team
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    Couple other things. In your simulation image above, you are simulating in reverse which might be your confusion as well.

    resversed.png

    Another thing you can look at is the info tab in the simulation. When "not" simulating in reverse, you should see the z position decrease for each pass.
     
  6. sjhilton

    sjhilton New
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    Ah, yes. I had never noticed that. Thanks for the quick answer.
     
    sharmstr likes this.
  7. Mark Carew

    Mark Carew OpenBuilds Team
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    Good catch Shawn :thumbsup:
     
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