LinuxCNC Error w/ Fusion 360 G-Code: "Radius to end of arc differs...."

samgaddis — Fri, 27 Jul 2018 23:48:16 GMT

Hey all, I spent a couple hours troubleshooting a CNC issue and am at a loss for what to try next. Does anyone here may have ideas on how to resolve?

Here’s the context

Everything works as expected if I produce the G-code in V Carve, but I’m very keen to use Fusion 360 for a number of reasons. And Fusion works fine in most cases – the problem arises, however, only when the model includes dogbone fillets.

The error I get is identical to what's shown in the image below albeit with different values because I forgot to grab a screenshot.

For reference, h ere's the model I’m using. To replicate the error you would export G-Code from Setup1 > TestCut2 and then try to open the resulting file in LinuxCNC:

I scoured forums for Fusion and LinuxCNC and tested various suggestions one-by-one, all to no avail. Here are the things I already tried:

changing the post processing properties to enable “Radius arcs.” This produces replaces the aforementioned error with a new one that says "Arc Radius Too Small"
Reducing tolerance to .0001 (per this forum post). I tried this in the following places:

Built-in tolerance in post-processing settings
Minimum circle tolerance in post-processing settings
Tolerence in the toolpath under "Passes"

Increasing the size of the fillets to be well beyond the tool diameter.
Creating the fillets using the dogbone add-in as well as creating them manually.
Toggling off Lead-In and Lead-Out transitions.
Changing the document unit from in to mm per some forum suggestion

I'm new to CAM so it's very possible I'm missing something obvious. Are there any Fusion or LinuxCNC experts out there with more ideas to try?

Any help is much appreciated!

Re: LinuxCNC Error w/ Fusion 360 G-Code: "Radius to end of arc differs....&

randyT9V9C — Sat, 28 Jul 2018 01:19:55 GMT

The issue is likely related to the arc fitting setting in linuxcnc being abnormally low by default. You need to adjust TOLERANCE_INCH and TOLERANCE_MM in your linuxcnc ini file.

See this thread:

https://forums.autodesk.com/t5/fusion-360-computer-aided/help-with-radius-vs-ijk/m-p/7234440#M34397

You should also check that your lead in/out arcs are something reasonable because very small arcs may also cause arc fitting issues.

topic LinuxCNC Error w/ Fusion 360 G-Code: "Radius to end of arc differs...." in Fusion Manufacture Forum

LinuxCNC Error w/ Fusion 360 G-Code: "Radius to end of arc differs...."

Re: LinuxCNC Error w/ Fusion 360 G-Code: "Radius to end of arc differs....&