Shapeoko 5 - Fusion360 - Circles with flat edges with 2d contour

[kdr213 (Kyle Rush)]

Hey everyone, I’m starting out my first project with the Shapeoko 5, which is a simple, circular box which I’m cutting out of walnut. However on my first attempt, the 2d contour to cut out the final shape turned out to be not circular (at all). I tried just doing a 2d contour around the 4" outline of the model, and I get the same result.

Using a 201 flat end mill. I tried adjusting my feeds and speeds to 20,000 rpm 45 in/min with a .1" step down. I’m using Fusion 360 for modeling and generating toolpath. I have a feeling the issue is in the gcode itself. Nothing in the machine suggests it’s skipping steps (And the oblong shape seems too consistent)

GCode is Here:

1001.nc (3.6 KB)

Here is what my toolpath looks like in F360.

Any ideas?

[WillAdams (William Adams (Carbide 3D))]

Check the machine mechanically, esp. the DACs and other aspects of the linear motion and ball screws.

If you don’t find anything obvious to address, let us know at support@carbide3d.com

[Tod1d (Tod (with 1 'd'))]

This is a simulation of your G-code. Dark blue means within 0.001", And if I measure any point on the surface it’s within 0.0002". I’d say your toolpath (Gcode) is spot on!

[WillAdams (William Adams (Carbide 3D))]

What tool is that for previewing the G-code thus?

[Tod1d (Tod (with 1 'd'))]

That’s NX. I made a post & simulator for my HDM

[kdr213 (Kyle Rush)]

Thanks Will! Not sure what a DAC is but maybe I inadvertently figured it out.

I took out my X axis stepper and noticed that the coupling on the threaded rod was loose. I took it off, lined up the little

[kdr213 (Kyle Rush)]

Thanks for taking the time to run the simulation! I’d agree this looks correct. Found out the issue was mechanical after all.