topic Mach 3 GCode creating unwanted spirals in Fusion Support Forum

Mach 3 GCode creating unwanted spirals

Christopher.J.HarrisNFTLL — Fri, 02 Jun 2023 02:46:06 GMT

Hello,

I am fairly new to using a CNC mill but can comprehend some things. (I am piecing it all together though). (not new to Fusion 360)

I have been having issues with the Fusion 360 post processing Gcode to Mach3. The issue creates dozens of spirals that are sometimes not even relative to the part i am trying to cut. I have pooled through the forums for days attempting to find any fixes but I haven't found this particular issue.

Any help would be wonderful.

For reference, I have the Mach3Mill profile in my fusion 360 post processor and I have tried both Absolute and Inclusive within the IJ mode within Mach3. Doesn't really change other than throwing me an error: "Radius to end of arc differs from radius to start"

Re: Mach 3 GCode creating unwanted spirals

HughesTooling — Fri, 02 Jun 2023 08:14:30 GMT

Only time I've seen this is when there's a short arc move and the control does a full circle because the start\end are too close.

Try changing these 2 settings on the post dialog to 0.25 and see if that helps.

Re: Mach 3 GCode creating unwanted spirals

Christopher.J.HarrisNFTLL — Fri, 02 Jun 2023 23:01:12 GMT

I have attempted to match your settings, I also have a number of other tabs that you dont have.

Re: Mach 3 GCode creating unwanted spirals

Christopher.J.HarrisNFTLL — Fri, 02 Jun 2023 23:29:09 GMT

I am unsure if the issue is coming from Mach3 or Fusion 360. however when I run the .TAP file in online NC viewers, they show exactly what the works are, yet when Mach3 gets it, it just likes to do circle work relative to the XY location.

Re: Mach 3 GCode creating unwanted spirals

HughesTooling — Sat, 03 Jun 2023 09:27:38 GMT

@Christopher.J.HarrisNFTLL wrote:

I have attempted to match your settings, I also have a number of other tabs that you dont have.

I said try 0.25mm, looks like you have 0.025mm. The picture I uploaded was for a different control that doesn't suffer from this problem. I noticed the latest Mach post chord length is set to 0.25 already, may be try increasing to 0.5 for min chord length.

I've just checked the latest Mach3 post in the library and it's set to incremental arc centres. You should see a line at the top of the g code with G91.1 indicating incremental arc centres.

If all else fails you could try radius arcs but they are not as accurate. Have you got one of the newest Mach3 programs? Are there any notes on versions that might have problems with arcs.

Mark

Re: Mach 3 GCode creating unwanted spirals

Christopher.J.HarrisNFTLL — Sat, 03 Jun 2023 22:55:40 GMT

Apologies, I tried to match what was in your screen and missed the decimal. I think we have a partial win here! It has automatically stopped the strange circular patterns (which i will call "reverse fibonachi sequences" for now. It appears to be running well in the demo version of Mach 3 i just installed to test any differences in settings.

I will run a hard test and get back to you!

Thankyou for your help so far!