Drilling op touches stock on horizontal move on LinuxCNC

[agren]

Hi all,

I think I've found a bug where the drilling operation is touching the stock while moving horizontally between holes. Technically it's seems to be positioned 0 mm from the top of the stock but neither my stock nor my table is perfectly level.

FreeCAD renders a lift to Safe Height as I would expect.
Camotics lift to Safe Height.
LinuxCNC does not lift to Safe Height.
The gcode is generated by the linuxcnc post processor.

A workaround is to manually set Start Depth for the operation to something above the stock.

Anyone noticed the same thing?

FreeCAD:

freecad.png (10.96 KiB) Viewed 1090 times

Camotics:

camotics-renders-path-as-expected.png (6.01 KiB) Viewed 1090 times

LinuxCNC (top of stock at Z=0):

linuxcnc-touches-stock-on-horizontal-feed.png (19.94 KiB) Viewed 1090 times

Code: Select all

OS: Ubuntu 20.04.4 LTS (MATE/mate)
Word size of FreeCAD: 64-bit
Version: 0.20.
Build type: Release
Branch: unknown
Hash: 134fa8b7ea5000ae648afcbe9b36c37a32974e89
Python 3.8.10, Qt 5.12.8, Coin 4.0.0, OCC 7.5.2
Locale: English/United States (en_US)

[agren]

The offending gcode can be seen here. The top of my stock is at Z=0 and my safe height is at Z=3.
G81...R0.000 in G99 mode tells LinuxCNC to go to Z=0 when the drill cycle is done.

Line 26-30 (Drilling the first hole):

Code: Select all

G90 
G99 
G0 X10.000 Y10.000 
G0 Z3.000 
G81 X10.000 Y10.000 Z-10.000 F100.000 R0.000 
G0 X20.000 Y10.000 
G0 Z3.000

[agren]

Suggested fix here.
It adds a retractheight argument to drill_generator.generate().

LinuxCNC lifts to Retract Height (Z=3) after fix:

linuxcnc-fix.png (12.04 KiB) Viewed 963 times

[sliptonic]

I think the default value for retractHeight should be None. Then the generator should check if it's none and use startpoint.z if so. Otherwise use the explicitly passed retractHeight.

Why don't you create a draft PR for the change and we'll go from there.

I would like to make the generators as thoroughly tested as possible. That's why they're structured as pure functions. So please add additional tests to
https://github.com/FreeCAD/FreeCAD/blob ... nerator.py

[agren]

Sounds like a plan!

[agren]

Draft pull-request here for those interested.

[sliptonic]

I think this looks great. I don't see any problems but let's see if we can get some others testing as well.

BTW, This thread is a master class on how to do it:
Excellent, clear description ... check
Pictures... check
FreeCAD info... check
Attached project file... check
Attached output... check
Suggested fix... check
Draft PR... check
Unit tests.... check

Brilliant!