Fusion Circular Interpolation?

I was digging through wondering why the programs were massive and didn’t seem to have any arc movements. I found the Fusion buildbotics post processor at r43022 has circular interpolation enabled, but Onefinity’s flavor had it specifically disabled on the next line.

Jump forward a bit and I see that Onefinity’s post processor was updated just a few days ago and now has an option for circles. A lot of my programs are now 10x smaller.

I don’t see any earlier discussion on this. Why was it disabled?

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Looks like that option was added in January, though I don’t know why they would enable it by default. Though the description is a little odd - I don’t know what ‘no’ means in this context - should the item be checked or not to get arcs in the gcode?


Unchecked is “no” and if you check it you get g2/g3 codes. I’m not sure this is actually beneficial with the stock controller yet

I’m looking at the 2021-03-18 releases for both OneFinity and Buildbotics from the Autodesk post library. Both have revision 43242 and looks like OneFinity is a clone of Buildbotics except for the last 2 lines.

Both have the line
allowedCircularPlanes = 0; // disable all circular interpolation
According to the Autodesk Post Processor Class Reference this means " Set to 0 to linearize all circular motion and undefined to allow any motion.

I’m wondering why this is so? I have seen some reference to fixing the circle problem but this seems a bit overkill.

Two week ago I had to reinstall everything on my pc and choose version 43242. After that I was not able to run some of my toolpath after reposting them (my 1F was making a very loud grounding nose and loose reference)… The old fusion360 did not have circular interpolation disable.

We noticed that after I re-enable it there was no problem anymore. I informed Onefinity support and they post this… Fusion 360 and Circles (arcs) (circular interpolation)

This was the PP announced to the forum. Small changes to the Autodesk one.
//allowedCircularPlanes = undefined; // allow any circular motion
allowedCircularPlanes = 0;
circular interpolation was commented out

could you share the post processor that you were using before this update happened. I’d like to compare

If you search here for onefinity the post processor history is available: Post Library for Autodesk Fusion 360 | Autodesk Fusion 360

The first version I have downloaded was timestamp 2020-12-10 21:52 on my workstation. When I compare with v43008 the only difference is:
(both file have $Revision: 43008 31731a89b929cfd1a62f827c2b8ebf233f944dc9 $)

Using the old file produce gcode with G03. The one on the forum don’t

I don’t know which revisions you have. Check the top of the file. I have three different ones locally

  $Revision: 43008 31731a89b929cfd1a62f827c2b8ebf233f944dc9 $
  $Date: 2020-11-17 14:36:18 $

  $Revision: 43221 a5a0aa6a6357c6456920970306b90da5de1f0892 $
  $Date: 2021-03-18 06:51:29 $

  $Revision: 43242 a5a0aa6a6357c6456920970306b90da5de1f0892 $
  $Date: 2021-03-18 06:51:29 $

The line you’re pointing to allowedCircularPlanes = 0; is what disables G2/G3 and forces Fusion to create lines out of circles.

As explained it seem to be a modified version of 43008 but without ‘allowedCircularPlanes = 0;’ line.

The file was probably shared on FB or forum prior the official post. The modified 43008 was the one I used and had no circular problem. The issue appear when I downloaded the current version available on autodesk 2 week ago. I have order 10022 and use fusion for last 4 month only.

If you want to see what was the issue on my machine when ‘allowedCircularPlanes = 0;’ is present look at the video for the test-bug project I shared with support. Everything is ok when enable.

Just a follow-up. I have contacted support last week for the grinding issue and circular problem. They contacted me this morning to test the 1.0.8b1.

On my test, the beta 1 fix the problem for linear cornering and linear circle toolpath. I was able to run fast toolpath with or without circular interpolation enabled.

Info provided > All cornering will run a little slower, because a code change in 1.0.8b1 causes the motion planner to actually enforce acceleration and jerk limits. You lose a little speed, but the machine is actually following the correct path, and not overloading what the steppers (torque) are capable of.