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Author Topic: Fusion360 Mach3 Radius to end differs from radius to start error  (Read 888 times)

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Hi, I'm getting the "Radius to end of arc differs from radius to start" error in Mach3. It does not prevent me from machining but randomly adds toolpath offsets and has left me with a pile of broken carbide and a pile of wasted stock.
It is only since trying to manually re-run certain Ops within mach that I stumbled upon the error at all.
Other wise it simply presents as the tool randomly offsetting in the x/y and ruining parts.

I have used rhinocam extensively in the past and never had this problem, but since moving to fusion it has plagued me. I am assuming that the problem is with the post processor. I am using the standard Mach3Mill post processor included with f360, I have latest stable version of mach3 and I'm using an ESS motion controller with the latest drivers/plugin.

I can rule out mechanical and electronic error as I have replaced everything other than the mill's castings chasing this problem before catching a glimpse of this 'radius differing' problem.

I have attached a copy of an NC file I have been trying to machine today. It fails consistently by offsetting toolpaths from where they are supposed to be, almost as if the workpiece origin is shifting, as can be seen in the attached image. After this error has occurred I can enter g0 x0 y0 into the MDI and it will not return to the original x0 y0 coordinates (also pictured). It is not being caused from lost steps or slipping couplers.

Any help resolving this would be appreciated

Offline Tweakie.CNC

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Re: Fusion360 Mach3 Radius to end differs from radius to start error
« Reply #1 on: April 15, 2021, 07:13:54 AM »
Generally the 'radius to end of arc' issue is caused by the incorrect IJ Mode being used (Config. / General Config.).

Can you post your <Profile> .xml file.

Tweakie.
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Re: Fusion360 Mach3 Radius to end differs from radius to start error
« Reply #2 on: April 15, 2021, 07:22:03 AM »
Thanks, IJ mode was set on Inc. I did try absolute mode and it didnt seem to help but I will try again tomorrow from scratch.

What is the difference between the two modes, as in, is there a reason to choose one over the other?

Offline Tweakie.CNC

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Re: Fusion360 Mach3 Radius to end differs from radius to start error
« Reply #3 on: April 15, 2021, 08:16:10 AM »
The IJ Mode relates to the absolute or incremental moves from which arcs are constructed within a CAD/CAM software.
Ideally your Gcode should contain G90.1 or G91.1 (as appropriate) to specify which method your CAD/CAM used to construct it's arcs.

Tweakie.
« Last Edit: April 15, 2021, 08:17:55 AM by Tweakie.CNC »
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