G code error Radius to end of arc differs from radius to start

[derinveron]

Hello, 

I'm getting the error that Radius to end of arc differs from radius to start. Can someone help me out with the settings I should change around? I've never gotten this error, and I don't really understand much about G-Code, I just use the software. I read other forums about this problem where some people suggested to change the tolerance to .0001, as well as check "radius arcs" in the post processing tab, neither of which worked. I've attached a screenshot of the error message and my file. 

[GeorgeRoberts]

Hello,

Thanks for posting. Can you please share a copy of the post-processor you are using? 

[derinveron]

Hi George, thanks so much for responding, can you let me know exactly what you mean by sharing a copy of the post processor, and how to do that? I'm not sure what that means, unfortunately I'm a beginner and don't really understand the g-code side of things, I just know how to make things run. I'm saving as an .ngc if that's helpful to know?

[derinveron]

This is just a guess, but do you mean copy the code from the post dialogue box? Would I do that by clicking the pencil "edit" icon to the right of Linuxcnc in my screenshot and copying the code? Because for some reason it's not allowing me to click on that button. Sorry if I'm not understanding, this is all like another language to me. Unfortunately I have to fix this to CNC something for my job

[engineguy]

@derinveron 

I downloaded your file and generated G code using the LinuxEMC Post Processor that I have here and loaded the code into three different Motion Control softwares, Mach3, Mach4 and CSMIO simCNC, so although none of them are LinuxCNC the code loads and runs correctly in all three so it suggests to me that there is a setting in your LinuxCNC that needs changing.

It does not look like a Fusion 360 issue to me altough changing settings in your operation may produce code that your LinuxCNC will accept 🙂

Have you tried asking about this on any Linux Forum ??

Can you attach the Post Processor you are using as @GeorgeRoberts has requested ? Go to your Post Processor Library, there should be an icon at the top of your Fusion screen in Manufacture mode as shown in the image below, find your LinuxEMC PP and then select it, right click, select Copy and then go to say your Desktop in your computer and save it there, then attach it to your reply.

[derinveron]

Hello, yes I've asked about it in the Linux forum but I haven't gotten any help. I've seen this question posted on Linux before but I really don't understand the solutions people are discussing, coding isn't something I ever learned so this all feels like another language. This article I've found seems to have come up with a solution or two, I would just need it explained by someone very patient I think.

Thanks for the explanation on how to attach the post processor. I copied it, but didn't see an option to paste it into my desktop or anything like you said (I'm using a Mac.), so I exported it and attached it as a .cps here. Hopefully that's what you need.

[engineguy]

@derinveron 

Before we try making changes to Post Processors or your LinuxEMC installation give this a try and see if it will load to your control, look at the start of your G Code and find this code, G91.1, try changing it to G90.1 and see if that will work, if it does then we can edit your Post Processor to do it.

Just something simple to try for now.

[GeorgeRoberts]

I've seen this problem before with the Prototrak post. In that post, there is some logic to 'adjust' the circle centre points and resolve the problem. 

I have put that logic into the post-processor you sent and have attached it here. Please could you try that out and let me know if it works? 

[Anonymous]

Thanks so much- I’m going to get to this around 8:30 EST when I’m by the CNC again. One question though, fusion doesn’t open the .nc editor when I save my post (I made another post about this, I think you saw it) so I downloaded another app that opens .nc’s and shows the code. I couldn’t find a function in that app that saves edited code though. I’m telling you all of this in case there’s an obvious route I should take that I don’t know about, thanks again!

[Anonymous]

Hi George, I’m gonna try that out around 8:30 EST when I’m by the CNC again. Thank you!

[Anonymous]

• Hi George, I’m gonna try that out after work when I’m by the CNC again. Thank you!

[engineguy]

@Anonymous 

Have a look in your "Preferences" for the Path to an Editor, if there is not one showing as in the image below try clicking on the button on the right and navigating to an Editor, for example the Visual Studio that you downloaded, it should be in your "Program Files" folder.

[HughesTooling]

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@engineguy wrote:

@derinveron 

Before we try making changes to Post Processors or your LinuxEMC installation give this a try and see if it will load to your control, look at the start of your G Code and find this code, G91.1, try changing it to G90.1 and see if that will work, if it does then we can edit your Post Processor to do it.

Just something simple to try for now.

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Don't think that'll work because the code will still have the arc centres (IJK) as incremental, just changing the G91.1 to G90.1 would mean the control would be expecting absolute (IJK). I was thinking it might be down to a mismatch between the control and Fusion but the code has incremental (IJK) so as long as the control recognises the G91.1 the code should be correct.

Mark

[HughesTooling]

@derinveron  I guess you could try the Radius Arcs option but you do lose some accuracy.

[HughesTooling]

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@derinveron wrote:

Hello, 

I'm getting the error that Radius to end of arc differs from radius to start. Can someone help me out with the settings I should change around? I've never gotten this error, and I don't really understand much about G-Code, I just use the software. I read other forums about this problem where some people suggested to change the tolerance to .0001, as well as check "radius arcs" in the post processing tab, neither of which worked. I've attached a screenshot of the error message and my file. 

---

Have you run other code successfully? Did it contain arcs? 

Looking at your picture it looks like it's failing on the first arc move in this program. The move is pretty simple and all adds up correctly. Move from Y23.3304 Z-0.085 to Y23.3554 Z-0.11 The arc centre is J is 0.025 from the Y and K0.0(Z) so add 0.025 to the start Y and subtract from the Z you get Y23.3554 and Z-0.11 so nothing vague there so should work.

[derinveron]

Hi Mark, thanks for your response. I found that out of the 10 files I had programmed tool paths for, one worked without an error message, and I'll attach the file here. I would appreciate any feedback as to what you think the difference is. It seems like from everything you wrote, my files should be working just fine? So I'm still not sure about what the problem is. I was CNCing just last week without any issues, so I'm also wondering what caused Fusion to create this issue.

[derinveron]

Hi Mark, just an update, checking off Arc Radius worked for one of my files randomly, but not the rest. I attached the file that it worked for and one of the files that it didn't work for. 

[derinveron]

Hello, I'm not sure what a .cps file does or how I should run this. If you could let me know that would be very helpful. 

[derinveron]

Hello, I changed the code to G90.1 and it still gave me an error message. I responded with this to someone else in this thread, but I just checked Arc Radius for one of my files and it worked, but it did not work for the rest of the models I have to cut for some reason. I've attached them here. I've also tried setting the tolerance to .0001 in post processor and it did not work.

[HughesTooling]

@derinveron  Something I noticed looking at the 2 files that worked was one had no vertical arcs and the other the first arc was not vertical. Might be grasping at straws but an easy test would be to try setting the vertical lead in radius to zero.