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CAM - HELP

Discussion in 'General Talk' started by Michael Cramer, Dec 18, 2020.

  1. Michael Cramer

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    Hey guys, noob here. Got my machine leveled and made the fixturing bed and all that fun stuff. On to trying to actually make my first cuts of something useful and feeling cocky since i successfully used it a few times. That was short lived. As soon as I hit run, the machine runs to the zero point (which is correct), then plunges for some reason, then runs across my work piece for whatever reason, leaving a massive groove in its path. I’ve attached some photos hopefully to have someone see what the heck is wrong. I’m using fusion360 for CAD and CAM. Can anyone please help me? Thank you!
     

    Attached Files:

  2. Rob Taylor

    Rob Taylor Master
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    That G53 G0 Z-10 is supposed to be comfortably above the workpiece. If not, that big XY G0 move afterward will do exactly that. It's only getting 4 lines into the op, so just diagnose where the machine thinks it is right at the beginning. If the machine thinks G54 home is where it's located in Fusion correctly, where does the mismatch come with G53 home?
     
  3. Michael Cramer

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    I apologize, I should have mention that I have no Dora how to read GCODE yet. I just finished assembling the machine and I’m very new to fusion360 cam. I only added that picture with hopes that someone might be able to see what I needed to change in my cam settings. I can’t for the life of me figure it out.
     
  4. Rob Taylor

    Rob Taylor Master
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    That was my point- if you don't become comfortable reading gcode- and fast!- you'll continue having these indecipherable problems. But I was giving you the area where the problem was so you don't have to try and read an entire file, but a) since I don't have access to the machine, I can't know exactly where the issue lays- could be with the home switches, could be something else- and b) it's vitally important to understand both the code and the machine in order to be able to run the machine.

    G53 is machine coordinates, which are fixed in place at your limit switch actuation points. G53 Z0 should be right at the top of your z-axis. If you're running CONTROL, it doesn't show you G53 coordinates, but they're there under the hood- G54 (G55, G56, etc- WCS) is just a constant offset from G53, not a real coordinate system in its own right.

    Expect to spend a lot of time poring over this page- G Codes - while you look at the top of your G-code file. Understand what the machine is doing line-by-line, and why it's actively trying to do something wrong- because of course, the machine only does what we tell it to.:ROFL:
     
  5. Michael Cramer

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    First of all, I really appreciate you trying to help me out explaining. Especially since I have no concept of most of the gcode stuff as of yet. I do plan on learning all about it (haven’t had time since I got it), and I’m really just trying to get like 2 simple projects done for Christmas (then go in depth learning), then this happens. Haha. So you were saying about the homing. This might be noob-ish of me, but I only zeroed the machine before running the program. Do I need to home the machine first, then zero the bit? Again, this was my first actual piece I’ve cut out. Could that be a reason? Because my zero point was spot on and I checked before every run. And my simulation on F360 everything looked good and I triple checked my settings. Just doesn’t make sense. I guess I’ll have to look into the gcode I suppose.
     
  6. Rob Taylor

    Rob Taylor Master
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    That would make sense. If you don't home, grbl considers wherever you turned it on to be G53 0,0,0. Which isn't usually much of an issue in X and Y, but obviously in Z it can cause problems. I guess it thought that G53 Z-10 was under the surface of the part.

    So yeah. Home first- always, immediately after turning the machine on. The machine has absolutely no idea where it is otherwise, that's literally what homing is for- to set G53 coordinates, which should always be exactly the same, +/-0.2mm or thereabouts. Unfortunately, in trying to be so beginner-friendly, CONTROL misses some information that I consider fairly essential to understanding (and diagnosing) the machine and ironically causes beginner-unfriendly problems like this.

    Watch what the G-code's doing as you work anyway, but (fingers crossed) this seems like a simple issue for now.
     
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  7. Michael Cramer

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    Thanks! I was wondering why homing was an option and if it was needed. I assumed zeroing each axis was all that it needed to find itself in space. I’ll try it tomorrow morning. I appreciate the help and I’ll read up on the gcode as in get time.
     
  8. JustinTime

    JustinTime Journeyman
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    Rob is very knowledgeable in this field so I feel bad contradicting him. If what you did is zeroing the axes, and it confirms to the 0,0,0 in Fusion360 than you shouldn't have the problem. I never home my machine (only my 3d printer does it), I don't even have the option to do it set up. The probe that OpenBuild is selling is not homing, it is setting 0,0,0 on the material that is going to be worked on, which I d manualy.

    I use SketchUp with SketchUcam, that David the swarfer upgraded to almost perfection, and in there I have 0,0,0 set at the bottom left corner and on top of the material. Check to see how it is set up in Fusion360 and that it is matched to the way you've set up your 0,0,0 on your machine. If it is not a match than that's where your problem may be.
     
  9. Rob Taylor

    Rob Taylor Master
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    The issue wasn't the G54 zero, the issue was the lack of safe G53 Z-zero (if that does get confirmed).
     
  10. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    David's Fusion Post does need homing, as the Z-safe moves are in Machine Coordinates. Home first to establish machine coordinates (for z safe moves etc) , then zero to tell it where the Stock is.
     
  11. Michael Cramer

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    Well I’ll be darned, homing the machine first was exactly what it needed! Thanks guys!
     
  12. David the swarfer

    David the swarfer OpenBuilds Team
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    If you have home switches then you should be being forced to run a home cycle before you start work, so I am wondering why you are not being forced?
    I am interested to see your GRBL settings, you can copy and paste them from the serial console tab. (all the $ variables)
     

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