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G Code Exported by Fusion - Return to zero problem

Anonymous

G Code Exported by Fusion - Return to zero problem

Anonymous
Not applicable

I'm a relative newbie to both Fusion 360 and to CNC in general. I have a homebrew CNC machine based on GRBL.

The problem I have is that for G code generated by fusion, a return to zero at the end of the job is slightly out - by 2 - 3mm - in all axes. Exactly how much each axis is impacted seems to vary with the job sent.

 

I don't think it's the machine (e.g. backlash, missing steps) as I can send complex G Code from other software such as Easel and it returns to the zero point flawlessly. If I import G Code from fusion into easel and then send it to the machine, then the error returns.

 

I've tried both the GRBL post processor in fusion and the "stroom" variant that's on Github.

Any ideas folks?

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seth.madore
Community Manager
Community Manager

I am somewhat skeptical that it's Fusion. I'm not saying that because I work for Autodesk, but mostly because every time this sort of issue arises, it ends up coming back to machine/control side.

 

What happens if you re-home your machine and run the code again? If it's cutting air the entire time and still does not return home, we are going to look into other areas. Are all set screws tight? Are all mechanicals absolutely secure? Is it losing steps due to some very small fast movements that are being skipped over?


Seth Madore
Customer Advocacy Manager - Manufacturing
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Anonymous
Not applicable

Hi Seth

I think I've mostly eliminated the chance of it being mechanical (but will try the cutting air test anyway). There's no limit switches on the machine yet so I can't home it as such (I just manually position then zero out work coordinates).

 

Jobs seem to actually execute perfectly - I've measured the results. It's just the return to zero thing means I struggle to run a second toolpath accurately. Other sources of G-Code - of arbitrary complexity - don't seem to exhibit this behaviour - it is specific to Fusion.

 

Thanks for the reply - and I'll keep plugging away!

 

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