QCAD Bugtracker

  • Status Assigned
  • Percent Complete
    0%
  • Task Type Bug Report
  • Category QCAD/CAM
  • Assigned To
    andrew
  • Operating System All Qt 6 Builds
  • Severity Low
  • Priority Very Low
  • Reported Version 3.32.9
  • Due in Version Undecided
  • Due Date Undecided
  • Votes
  • Private
Attached to Project: QCAD Bugtracker
Opened by Mgoodboy - 12.05.2026

FS#2724 - QCAD/CAM QT6 Freeze during CAM EXPORT.

Versions QT6 3.32.8.0, 3.32.9.0 on WIN10 and LINUX Ubuntu 25.10 (don’t work in WIN7)

Versions QT5 OK on WIN7, WIN10 and LINUX

My PlanetCNCW64 software accepts G41/42 but gave an error on generated g-code G40 (“Arc without IJK or R is not valid” G40 X85.6 Y62.24 Their bug?). So, I had to fill “Interpolate axes with line segments” in CAM Configuration. A little window QCAD CAM “Regenerating tool path…” opens, shows 50% all the time, and a button “Abort” that closes that window when clicked, but doesn’t stop the process; a lot of messages “regenerating tool paths…” run at the bottom with great speed, as expected.

With QT6 but not QT5, after a while, these messages start slowing more and more, when I believe the arc segments are being generated, but keep a normal speed on lines, till the program freezes. During this process, with both QT6 and QT5, the memory used is growing, but is not released until the program is closed. Garbage collection problem?

CVH commented on 13.05.2026 08:35

Hi,

First:
Several controllers that I know of don't accept a G41/42 compensation move given a circular entry motion. For example a circular Lead-In. A gradual offset to circular would be some odd spiral motion and most controllers can not cope with that.

The first motion must always be a linear move.
Such can easily be compensated to end in an offset position.
Said to be fixed somehow.

You did fall back on interpolating arcs as (very) short line segments.
A better solution would be to not use G40/41/42 compensation.
And to let QCAD/CAM generate the offset path itself, instead of relying on the controller.

Typically a post-processor with 'offset' in the display name.
Or the specific script includes:

this.outputOffsetPath = true;

Perhaps you can attempt that first.

For the rest it is unclear what went wrong.
With a CAM drawing example Andrew could try to replicate the issue under Qt6.

I think that the large memory usage has more to do with the vast amount of interpolated segments. The garbage collector only acts on intermediate values and/or objects that are no longer in use.

Regards,
CVH

Mgoodboy commented on 13.05.2026 22:04

Thank you very much for your comment, CVH.

Besides being quite old, in a sense I’m a newbie, and your explanation is like a foreign language I can’t cope! :-) I didn’t choose the compensation, CAM did, I think… PlanetCNC did not complain about the previous G41, only about G40. Of course, a huge number of segments are being generated since I choose short ones to get more precision, so a corresponding amount of memory should be needed… or does it not? I don’t know how and why the data is being used this way, (holy ignorance! :-) ), but is it needed to keep all the data in memory, all the time and till the end of the program? The g-code generated is only 348KB, the program for this project 340MB, but during the export rises to more than 6GB!Why the green cursor starts and ends with 50% instead of showing the progress of the process? Why the Abort button closes the little window but do not stop the process? When the “slowing” start, it is possible to close the program window, but after some time, I have to kill the program to close it.This is to be used in a little CNC that I built, with only a 500W Spindle, so I’m using 12 passes for the project. Is it needed to keep all the data, all the time and even after the generation of the g-code, to the end of the program? Seems peculiar… As you well wrote,” The garbage collector only acts on intermediate values and/or objects that are no longer in use”.

Please don’t get me wrong, this is one of the most spectacular pieces of software I found, and I dig a lot, there’s more, a license that allow me to run the program in all the Oss and computers I want, it’s unique! This is not only Technique, this is Art!

Best Regards,
Mgoodboy

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