Arc radius too small

[mk00]

Hi,

KmotionCNC sometimes tells "arc radius too small" on my programs, although in Mach3 all is good. At this moment I solved this by increasing radius by few microns manually. It there a way to adjust arc endpoint tolerances in KmotionCNC?

Thank You.

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[TomKerekes]

Hi mk00,

The code only allows the radius to be short of the required distance by a fixed limit of 1e-12. Do you have an example GCode Fragment? Defining a near semi circle using Radius mode may cause large path errors as the slightest change in the specified values can shift the circle center by a significant amount. Does your CAD have another option? Or can it specify more digits of precision?

Regards

[mk00]

Hi, Tom

Here is example program. May be it is possible to modify postprocessor, but i dont know how. I`we read that LinuxCNC have option for adjusting arc endpoint tolerance.

[cncjack01]

may be you use inch, please check ,some control system can not us inch ,so the system will show the "arc radius too small".

[mk00]

may be you use inch, please check ,some control system can not us inch ,so the system will show the "arc radius too small".

No, both CAM and KmotionCNC in millimeters. If I will increase radius manually by 0.001 all will work

[TomKerekes]

Hi mk00,

We will add an option to change the Tolerance.

Using R mode is a poor way to specify a semi-circle. I did the math for a 100mm Radius. Changing R by only 1um shifts the arc center by 0.477mm. So most CAM systems avoid this.

=SQRT(100^2 - (100 - 0.001)^2) = 0.477

Regards