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IDProjectCategoryView StatusLast Update
0002916PathFeaturepublic2021-08-25 15:40
ReporterEdgarRobles Assigned To 
Status confirmedResolutionopen 
PlatformLinuxOSUbuntuOS Version16.04 LTS
Product Version0.18 
Target Version0.20 
Summary0002916: Add knife align up function to locate knife at begining cut precisely
DescriptionYou can see similar function in dxf2gcode application
it align up the knife before begin to cut and between cut inputs.
FreeCAD Information



2017-02-22 12:37

administrator   ~0008403

@EdgarRobles Thanks for the report. Just a tip to help bug triage and expediting your request: please always try to:
  • open a forum thread before opening a ticket to generate discussion
  • if the indication from the community is to open a ticket then do so
  • link said ticket <=> thread
  • to paste the contents of Help > About FreeCAD > Copy to clipboard in to the ticket/thread


2017-02-22 14:20

reporter   ~0008406

Here is what i post but it is not in english
ty didn't know about triage.


2017-02-22 16:48

administrator   ~0008407

@EdgarRobles you can also ask in
Bug triage is when someone goes through bugs organizing them for clarity and helps get them to the correct people. ;)


2017-02-23 22:56

manager   ~0008415

Can you describe better what kind of behavior you're looking for in the 'align' function?
Should the program pause to let the user manually align the knife or should it add some kind of lead-in move to give the knife time to pivot.

If it's a lead-in move, how do I determine a safe position to start from?


2017-02-24 19:58

reporter   ~0008423

Sure, If you try to make a dress-up knife path as fast as you start to cut it, you will see knife is not aligned at one specific direction; I think one simple solution could be say the final user align it by hand before start cutting always at the same direction.
Other case might have to change it's between cuts for example if you have two squares
at moment you wanted to cut the second square, it will be necessary to get down the knife and re-align (make a semi-circle to point the knife towards the first trajectory)

I saw a little issue on the path you can see it from here:
 in the "dragknife.png" image.
I saw on second edge that not do knife dress-up operation; I did a second test and always it misses the second edge.


2017-02-24 20:02

reporter   ~0008424

This attach g code is from dxf2gcode dressup knife function, i think a example file is better than my words. xDD
Mascara de soldadura.dxf (28,836 bytes)


2017-02-28 19:29

developer   ~0008476

Would one way to solve this would be to "drag the knife into the starting position" - if that makes any sense. Probably easiest to let the user specify a starting position from where to start dragging.

The same is true for every independent Path. Whenever there is a rapid-move (aka the knife gets lifted off completely), there needs to be a "lead in" segment to orient the knife.


2017-03-23 23:55

administrator   ~0008692

changing to feedback to keep track of ticket.


2017-04-28 16:21

administrator   ~0008809

@sliptonic do you mind weighing in on the discussion at your earliest convenience?


2017-05-10 13:41

manager   ~0008938

I don't have a good solution at this time. I think the most expedient solution is for the dressup to add a pause event to give time for the user to align the knife.

Basically, after every G0 rapid, check if we are descending to the cut depth. If so, descend to just above the material, insert a M0 command, descend to cut depth, and continue. I don't know if an M0 will work on controllers other than LinuxCNC

This logic could be implemented as another entry dressup and applied optionally to dragknife dressed operations.


2017-05-11 21:27

administrator   ~0008965

@sliptonic should I change this to a ticket as a feature request?


2017-05-25 15:51

manager   ~0009137

The simple solution of pausing and waiting for the operator to align the knife won't work for many machine controllers that don't allow interaction. For example, Smoothie doesn't even have a pause command. I don't know of a way to safely determine an entry position where a big entry arc could be cut to guarantee starting angle.
I think it should be left as a feature request. Maybe someone will come along with a bright idea.


2017-05-26 13:15

administrator   ~0009147

Changed ticket to Feature Request.


2020-01-06 16:36

administrator   ~0014002

Opened a thread in the Path subforum for discussion:


2021-08-25 15:39

administrator   ~0015864

Summary by sliptonic:

There's consensus that something is needed but no ideas about how to achieve it. For a simple single-wire profile, it's pretty easy. Let the user pick a point to start at. That doesn't work in all cases because a profile might have many wires where the tool is lifted between. What's needed is an algorithm that will consistently pick a safe starting point regardless of the profile.



2022-03-03 13:55

administrator   ~0016517

This ticket has been migrated to GitHub as issue 5682.

Issue History

Date Modified Username Field Change
2017-02-22 06:02 EdgarRobles New Issue
2017-02-22 06:02 EdgarRobles Tag Attached: dragknife
2017-02-22 12:37 Kunda1 Note Added: 0008403
2017-02-22 14:20 EdgarRobles Note Added: 0008406
2017-02-22 16:48 Kunda1 Note Added: 0008407
2017-02-23 22:56 sliptonic Note Added: 0008415
2017-02-24 19:58 EdgarRobles Note Added: 0008423
2017-02-24 20:02 EdgarRobles File Added: Mascara de soldadura.dxf
2017-02-24 20:02 EdgarRobles File Added: Mascara de soldadura codigo G.ngc
2017-02-24 20:02 EdgarRobles Note Added: 0008424
2017-02-28 19:29 mlampert Note Added: 0008476
2017-03-02 11:51 Kunda1 Target Version => 0.17
2017-03-23 23:55 Kunda1 Status new => feedback
2017-03-23 23:55 Kunda1 Note Added: 0008692
2017-04-28 16:21 Kunda1 Note Added: 0008809
2017-05-10 13:41 sliptonic Note Added: 0008938
2017-05-10 13:46 Kunda1 Status feedback => confirmed
2017-05-11 21:27 Kunda1 Note Added: 0008965
2017-05-25 15:51 sliptonic Note Added: 0009137
2017-05-26 13:15 Kunda1 Category Patch => Feature
2017-05-26 13:15 Kunda1 Note Added: 0009147
2018-02-08 15:36 sliptonic Product Version 0.17 => 0.18
2018-02-08 15:36 sliptonic Target Version 0.17 => 0.18
2019-01-22 05:26 sliptonic Status confirmed => feedback
2019-01-22 05:26 sliptonic Target Version 0.18 => 0.19
2019-04-06 19:08 Kunda1 Status feedback => acknowledged
2020-01-06 16:36 Kunda1 Note Added: 0014002
2021-02-06 06:33 abdullah Target Version => 0.20
2021-08-25 15:39 Kunda1 Note Added: 0015864
2021-08-25 15:40 Kunda1 Status acknowledged => confirmed