[FluidNC Issue#1573] Problem: GCode error with DragKnife About GRBL HAL

Issue #1573 | 状态: 进行中 | 作者: heiserhorn | 创建时间: 2025-09-24

Wiki Search Terms

Alarm, Gcode error

Controller Board

Jackpot

Machine Description

LowRider 4

Input Circuits

Configuration file

The default LR4 config file

Startup Messages

None

User Interface Software

WebUI 3

What happened?

I am trying to work with Drag Knife. I have generate the path using FreeCAD and DragKnife dressup. The machine gives ma an Alarm 17 (Gcode error) and this happens when the blade is lifted to perform the rotation outside of the shape I am cutting. The code works on other machines with LinuxCNC.

GCode File

(Exported by FreeCAD)
(Post Processor: script_module)
(Output Time:2025-09-19 14:54:08.216606)
(Begin preamble)
G17 G90
G21
(Begin operation: Fixture)
(Path: Fixture)
G54
(Finish operation: Fixture)
(Begin operation: Drag Knife003)
(Path: Drag Knife003)
(Drag Knife003)
(Begin toolchange)
( M6 T2 )
(Finish operation: Drag Knife003)
(Begin operation: DragknifeDressup001)
(Path: DragknifeDressup001)
(Profile003)
(Compensated Tool Path. Diameter: 0.1)
G0 X0.000 Y0.000 Z7.000
G0 X150.949 Y209.950 Z7.000
G0 X150.949 Y209.950 Z5.000
G1 X150.949 Y209.950 Z1.000 F500.000
G2 X146.371 Y70.928 Z1.000 I-2796.286 J22.499 K0.000 F500.000
G2 X135.916 Y26.966 Z1.000 I-129.054 J7.466 K0.000 F500.000
G2 X118.904 Y12.214 Z1.000 I-23.881 J10.356 K0.000 F500.000
G2 X100.500 Y10.050 Z1.000 I-18.288 J76.189 K0.000 F500.000
G1 X60.500 Y10.050 Z1.000 F500.000
G2 X42.096 Y12.214 Z1.000 I-0.116 J78.351 K0.000 F500.000
G2 X25.084 Y26.966 Z1.000 I6.869 J25.107 K0.000 F500.000
G2 X14.629 Y70.928 Z1.000 I118.599 J51.429 K0.000 F500.000
G2 X10.051 Y209.950 Z1.000 I2791.708 J161.521 K0.000 F500.000
G2 X10.028 Y212.980 I2796.287 J22.499
G0 Z1.500
G3 X13.081 Y209.950 I0.023 J-3.030
G1 Z1.000
G1 X150.949 Y209.950 Z1.000 F500.000
G1 X150.949 Y209.950 Z0.000 F500.000
G1 X153.979 Y209.950
G0 Z1.500
G2 X150.923 Y206.915 I-3.030 J0.000
G1 Z0.000
G2 X146.371 Y70.928 I-2796.260 J25.535
G2 X135.916 Y26.966 Z0.000 I-129.054 J7.466 K0.000 F500.000
G2 X118.904 Y12.214 Z0.000 I-23.881 J10.356 K0.000 F500.000
G2 X100.500 Y10.050 Z0.000 I-18.288 J76.189 K0.000 F500.000
G1 X60.500 Y10.050 Z0.000 F500.000
G2 X42.096 Y12.214 Z0.000 I-0.116 J78.351 K0.000 F500.000
G2 X25.084 Y26.966 Z0.000 I6.869 J25.107 K0.000 F500.000
G2 X14.629 Y70.928 Z0.000 I118.599 J51.429 K0.000 F500.000
G2 X10.051 Y209.950 Z0.000 I2791.708 J161.521 K0.000 F500.000
G2 X10.028 Y212.980 I2796.287 J22.499
G0 Z1.500
G3 X13.081 Y209.950 I0.023 J-3.030
G1 Z0.000
G1 X150.949 Y209.950 Z0.000 F500.000
G1 X153.979 Y209.950
G0 X150.949 Y209.950 Z7.000
G0 X150.949 Y209.950 Z7.000
(Finish operation: DragknifeDressup001)
(Begin postamble)
M5
G17 G90
M2

Other Information

No response

#1 – MitchBradley 于 2025-09-24

It looks like an arc tolerance problem. In the sequence

G1 X153.979 Y209.950
G0 Z1.500
G2 X150.923 Y206.915 I-3.030 J0.000

the center point of the arc that starts at X153.979 Y209.950, with distance I-3.030 J0.000, is X150.949 Y209.950, and the radius is just the 3.030 I value. But the radius from that center point to the target point X150.923 Y206.915 is 3.03511, which exceeds FluidNC’s .005 tolerance for arc computation errors.

Does FreeCAD have an option for more precise calculation?

#2 – heiserhorn 于 2025-09-24

Thanks for looking into this. I opened a bug with FreeCAD because I do not see an option to increase precision for the arc calculation when using the Dragknife dressup. Here’s the link: https://github.com/FreeCAD/FreeCAD/issues/24203

#3 – MitchBradley 于 2025-09-24

That link goes nowhere – the url field just says “url”.

BTW, if you need to open future issues, please provide all of the requested information. Here in FluidNC land, we have no idea what the default config for a Lowrider4 is. I tried to Google it and didn’t find anything. Also, we usually need the startup messages, for many reasons including knowing which version of FluidNC. You can get them by sending $ss, as indicated in the instructions.

#4 – heiserhorn 于 2025-09-24

Not sure what is happening with the link. I I paste it in the browser it works but when I click directly on it it doesn’t.

I will make sure to provide both info next time.

Thanks again.

#5 – MitchBradley 于 2025-09-24

Do these have any effect?