Ticket #6232 - Gcode generated by Path engrave skips some lines

[bmsaus4ax]

Just to be clear, if you do not touch the sketch and just make an engraving Path out of it, do you get what I get? If so, then the version you have behaves the same as mine and I would think this is a bug. Do you agree? Again, if I export the sketch as a dxf file and process that with with another program (dxf2gcode), it produces the complete "6".

I can get the shape to produce the required path if I select the first or last edge and then use Path->Finish Selecting Loop -> Add(in Base Geometry)
This seems to overcome the need to fully constrain the sketch, by defining the connections at selection.

From my experience working with PathShape in creating paths via macro, there is a Property "Nearest K " which nominates the nearest number of vertices considered during sorting for the path. This property is not visible (even with show all) in the engraving job but may have an effect deeper down in the path generation?? I don't know if this is involved in engraving paths or could be the case.
If each edge is considered as a separate "Path" this may contribute to the selection of segments in the "six" object, some may be outside the area of consideration?? Again just theorising.

Edited to add FreeCAD info

OS: Ubuntu 20.04.2 LTS (ubuntu:GNOME/ubuntu)
Word size of FreeCAD: 64-bit
Version: 0.20.25065 (Git) AppImage
Build type: Release
Branch: master
Hash: 4de2ad46b2b9c78ac2721a0dbea7c19306261095
Python version: 3.9.4
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.2
Locale: English/Australia (en_AU)

[chrisb]

if you do not touch the sketch and just make an engraving Path out of it, do you get what I get? If so, then the version you have behaves the same as mine and I would think this is a bug. Do you agree?

Yes and yes. Not touching and recompute or create a completely new job behaves as yours. And yes, it is a bug. That's why I pinged mlampert.
He may be busy with other things, so you should create a ticket in the tracker to not forget the issue.

[chrisb]

This may help finding the bug. I just tried the profile operation without compensation: it creates the same erroneous path.

[munther_hindi]

bmsaus4ax, crisb, thanks for taking the time to look into this. This is my first post and I'll have to try and figure out how to post a bug report. Was not so obvious on a first reading.

bmsaus4ax, I have hundreds of these characters in the job I am sending to the CNC, so as a practical matter it is just not feasible to select an element of each, one by one, and then click on complete the loop. I have found a somewhat faster work-around, though still a little tedious. The letters I wish to engrave start out as Path::Feature objects. The Path workbench produces nothing if I try to engrave those. By selecting all the letters (the Path::Feature objects) and using Draft->Convert Bi bidirectionally to sketch, all the letters were put into a single sketch which contained all the letters lines); I could then select that single sketch and do a Path engrave on it. That seemed to work, except I noticed after the machine was done engraving that certain segments were missing (which led to this post). If I now select the sketch and use Draft->Convert bidirectionally again, Draft produces Wires and Lines (hundreds of them), but since are consecutive in the document tree, it is relatively easy to select all of them and produce a Path engrave operation that works correctly. A tedious process, but it works. It seems to me either the sketch->engrave should work completely or not at all; so working 90% of the time seems to me to be a bug. I will try to file a bug report when I figure out how. Thanks for all your help!

[munther_hindi]

Just to be clear, if you do not touch the sketch and just make an engraving Path out of it, do you get what I get? If so, then the version you have behaves the same as mine and I would think this is a bug. Do you agree? Again, if I export the sketch as a dxf file and process that with with another program (dxf2gcode), it produces the complete "6".

I can get the shape to produce the required path if I select the first or last edge and then use Path->Finish Selecting Loop -> Add(in Base Geometry)
This seems to overcome the need to fully constrain the sketch, by defining the connections at selection.

From my experience working with PathShape in creating paths via macro, there is a Property "Nearest K " which nominates the nearest number of vertices considered during sorting for the path. This property is not visible (even with show all) in the engraving job but may have an effect deeper down in the path generation?? I don't know if this is involved in engraving paths or could be the case.
If each edge is considered as a separate "Path" this may contribute to the selection of segments in the "six" object, some may be outside the area of consideration?? Again just theorising.

Seems plausible. Please next post for another workaround I found. Thanks!

[GeneFC]

Seems plausible. Please next post for another workaround I found. Thanks!

I fixed your first post by adding the images directly.

Please do not use external links for relatively small image files. It is much more helpful to include them directly into your posts. Use the "Attachments" tab below the edit window.

Gene

[munther_hindi]

Seems plausible. Please next post for another workaround I found. Thanks!

I fixed your first post by adding the images directly.

Please do not use external links for relatively small image files. It is much more helpful to include them directly into your posts. Use the "Attachments" tab below the edit window.

Gene

Ah! Below the window! I did not notice that, only the insert image icon on top. Thanks for the correction and point that out!

[Kunda1]

Ticket has been migrated to Github: please see https://github.com/FreeCAD/FreeCAD/issues/6232 and notate it. Thanks!

[Kunda1]

Any progress here?
Please also update issue #6232

[sliptonic]

Closed the issue. Resolved by pr 6394