[solved] Accounting for burn of laser cutter

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alandran
Posts: 5
Joined: Tue Mar 13, 2018 6:55 am

[solved] Accounting for burn of laser cutter

Postby alandran » Thu Apr 05, 2018 7:11 pm

I am using Inkscape to prepare data for laser cutter. One of the last step is modifying dimensions to account laser burn. i.e for cutting out 1cm square, source file must specify 1.04 cm square. For squares/circles/etc. process is simple enough. Sadly there are more complicated shapes.

Using inset/outset doesn't provide clean result (e.g. straight lines aren't preserved).

Currently I do following steps:
  1. set stroke width on everything to burn width
  2. convert strokes to objects
  3. break objects to paths
  4. remove "inner" paths

which is tedious process.

At the end I end up with two files. One with clean dimensions (for later editing) and one for actual cutting. When I need to correct something (frankly quite often), I end up either editing "clean" file and redoing steps from above or editing "cutter" file while doing math in my head to account actual positions/dimensions.

There are simillar posts but they are trying to solve minimum angle for corners (for CNC milling machine) or trying to decipher inset/outsep step/scale magic. But as I stated before, inset/outset provides (fo me) significantly worse results than stroke method.

I was wondering if there is better approach? Script maybe (or preferably LPE)?

Thanks
Last edited by alandran on Fri Apr 06, 2018 6:02 am, edited 1 time in total.

tylerdurden
Posts: 2328
Joined: Sun Apr 14, 2013 12:04 pm
Location: Michigan, USA

Re: Accounting for burn of laser cutter

Postby tylerdurden » Thu Apr 05, 2018 9:19 pm

Please attach an example file that includes an object and its duplicate that exhibits the outset issue.

Thanks.
Have a nice day.

I'm using Inkscape 0.92.2 (5c3e80d, 2017-08-06), 64 bit win8.1

The Inkscape manual has lots of helpful info! http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

jabiertxof
Posts: 184
Joined: Wed Feb 06, 2013 6:47 am

Re: Accounting for burn of laser cutter

Postby jabiertxof » Thu Apr 05, 2018 9:36 pm

In 0.93 you have offset LPE that maybe can help you.
https://www.youtube.com/watch?v=xfzvXD9jrAk
Thanks Mihaela for point me here!

alandran
Posts: 5
Joined: Tue Mar 13, 2018 6:55 am

Re: Accounting for burn of laser cutter

Postby alandran » Thu Apr 05, 2018 10:31 pm

tylerdurden wrote:Please attach an example

SVG Image
https://www.dropbox.com/s/sbkdzeukfnxuvtp/test.svg?dl=0

Done on Inkscape 0.92.2. Inset/outset setting at 0.2mm. Doesn't seems like it but I presume that's the confusion with the scale/unit.


jabiertxof wrote:In 0.93 you have offset LPE


Thanks for the tip, seems like solution. Will try. Do you know what units is the offset, though? From video seems that youn can't specify units.

tylerdurden
Posts: 2328
Joined: Sun Apr 14, 2013 12:04 pm
Location: Michigan, USA

Re: Accounting for burn of laser cutter

Postby tylerdurden » Fri Apr 06, 2018 12:55 am

Thank you for the test file.

You may find setting the scale of your default documents to 3.77953 (units mm) will solve the issue.

Similar to this issue: viewtopic.php?f=5&t=33535&p=104046&hilit=bug#p104046

I have tested your uploaded file successfully.

TD
Have a nice day.

I'm using Inkscape 0.92.2 (5c3e80d, 2017-08-06), 64 bit win8.1

The Inkscape manual has lots of helpful info! http://tavmjong.free.fr/INKSCAPE/MANUAL/html/

jabiertxof
Posts: 184
Joined: Wed Feb 06, 2013 6:47 am

Re: Accounting for burn of laser cutter

Postby jabiertxof » Fri Apr 06, 2018 1:06 am

alandran wrote:Thanks for the tip, seems like solution. Will try. Do you know what units is the offset, though? From video seems that youn can't specify units.
Top

It use document "Display units"

alandran
Posts: 5
Joined: Tue Mar 13, 2018 6:55 am

Re: Accounting for burn of laser cutter

Postby alandran » Fri Apr 06, 2018 6:01 am

tylerdurden wrote:You may find setting the scale of your default documents to 3.77953


Interesting, I didn't expect this to be such difference. Resulting object is indeed mostly dimension wise correct (presumably because actual offset length is now almost 4times smaller) Unfortunately there is still artefact on the left "spike", where outset generates little bumb (one extra node and smoothed edge). Not normally problem, but in laser cutting world this mean that counterpart may or may not fit.

Are there any benefits for usign "correct" scale? (other than fixing outset/inset)

jabiertxof wrote:It uses document "Display units"


I managed to download current master version and can confirm that behaviour matches exactly my needs. There are some glitches, but I assume that they are part of the bleeding edge expirience (will try to confirm them in appropriate forum).

_____________

Thank you both very much for help, I appreciate it.

jabiertxof
Posts: 184
Joined: Wed Feb 06, 2013 6:47 am

Re: [solved] Accounting for burn of laser cutter

Postby jabiertxof » Fri Apr 06, 2018 7:55 am

Is great to know. Cheers


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