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Author Topic: Help adding connectors to an SVG for laser cutting  (Read 3200 times)

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Offline bmudry

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Help adding connectors to an SVG for laser cutting
« on: January 10, 2017, 08:57:43 AM »
Hi everyone,

I assume this is a common requirement, and that I am just searching by a wrong term, but I can not find anything on how to do this and wondering if someone can point me in the right direction.

What I am looking for is a way to add either breaks around a designed path, or ideally add breaks and then fill them with short splines of a different colour so that I can set different cut parameters for that section.  Those small sections would be someplace between 0.1mm to 0.3mm.

This is so that I can cut a whole page of parts, but leave all the parts connected to the page for easy shipping, rather than shipping a bag of parts.  Kind of like the sprue connections on plastic model parts.

Sorry to have to ask such a basic question, but I am convinced that I am just not able to find it due to know knowing the proper term.  Surely others do this all the time.

Offline brynn

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Re: Help adding connectors to an SVG for laser cutting
« Reply #1 on: January 10, 2017, 01:01:06 PM »
 :w1:

I don't know if there is any "professional" way to do it.  But I would just add 2 new nodes in the place where you want the break.  Using the Node tool, double-click on the path in the place where you want the new node.  Then click  the segment to select both new nodes, then "Delete segment between 2 nodes" button, on the Node tool control bar.

Maybe others will know more about this than me?
  • 0.92.2
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Offline bmudry

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Re: Help adding connectors to an SVG for laser cutting
« Reply #2 on: January 10, 2017, 01:12:41 PM »
Thanks Brynn,

That is how I have been handling it for some very simple things, but I have searched on and off for the last year thinking there must be a simpler way.  Surely someone has been able to do this in an easier method.  Some of my 8" x 11" sheets have over 50 pieces on them, currently I just cut them out and bag them, but as production ramps up, I would like to change this to just sending flat sheets with parts still in the sheet.  I keep assuming I just can not find how to do it since I do not know the proper term for it, but not sure at this point.

One thing that came close was creating a small (0.2mm) straight and then doing a pattern object on path, BUT three issues, if the repeat distance happens to fall on a corner your screwed (it doesn't wrap or turn to an L or curve), if your object is curved your screwed as well, and most importantly it just overlays the small red line, it doesn't break the original path nor can I find a way to make it then subtract it from the path as it just disappears (I expect because it is taking a line away from the edge of a solid). 

Almost any laser cut mdf or plywood model terrain you buy comes setup with these little connectors or tabs or whatever they are called, holding them in.  Some companies provide sheets with hundreds of parts held in.  I keep thinking there has to be some automated process, somewhere, if not in inkscape then in something, and I keep thinking if I find out the name of the feature I will find it in everything....  I could be very wrong though! And probably am due to the fact that I have not find something already.

Offline brynn

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Re: Help adding connectors to an SVG for laser cutting
« Reply #3 on: January 10, 2017, 05:38:49 PM »
I suppose that the 50 pieces on a sheet are not identical objects?  That would be too easy, haha.  If they were all the same, you could simply do it once, and then clone that object 49 times.

One thing that came close was creating a small (0.2mm) straight and then doing a pattern object on path, BUT three issues, if the repeat distance happens to fall on a corner your screwed (it doesn't wrap or turn to an L or curve), if your object is curved your screwed as well, and most importantly it just overlays the small red line, it doesn't break the original path nor can I find a way to make it then subtract it from the path as it just disappears (I expect because it is taking a line away from the edge of a solid).

I don't understand what is "....doing a pattern object on path.....".  Can you say exactly which steps you take - which buttons or key shortcuts or menu items?

You must be creating these paths by some automated process?  Could you describe the process?  I'm only asking in case there might be some place along the way, where this could be done easier.  Like I'm thinking somehow those nodes could be added from the start, and not have to be added later.

If you can get the nodes added at the same time the paths are created, then you can hold the Shift key, and click on each segment, on each of the 50 paths, and break all the paths at once, with one click on that button .  Or if the nodes are aligned in the right way, you could make the selection faster by dragging the selection box.

To be honest, this sound like a perfect candidate for an extension.

Well, before we talk about extensions....  If you know how to write scripts, or know someone who can, and how to use Inkscape's command line features, you could write a script and use it through the command line.  That would be more or less automatic.

Or the other thing, as I mentioned, an extension.  Essentially, an extension would be just a polished up version of a script, so that it has a nice little dialog to configure whatever options there might be, and so that it can be installed in Inkscape.

I can give you a lot more info about possibly getting an extension written.  But first, I want to understand that technique you referred to, and make sure we can't find a way with existing features.

Edit

One more question.  How like or unlike are these paths?  Is each sheet entirely different?
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Offline bmudry

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Re: Help adding connectors to an SVG for laser cutting
« Reply #4 on: January 10, 2017, 06:38:03 PM »
The exact commands I tried to use were as an example:

- Draw a 40mm x 40mm square to be held in by 4 "connectors" one in the middle of each side, set to black
- Draw a 2mm "connector" in the middle of one side, set to red
- Select both, then: Extensions - Generate from Path - Pattern along path
- At work I could use 38 for spacing and repeated for the settings and it would put one red line in the center of each side, for some reason at home it is not, the spacing is strange, likely something to do with settings, but you should get the idea.

No, each piece is different.  A good example can be found on this website: http://shop.microartstudio.com/district-5-l-apartment-1-p-800.html or here: http://tomschadleminiatures.blogspot.ca/2013/06/underground-lasers-terrain.html

I make the same kind of terrain as shown there for war games, but now with a more powerful laser, I want to keep pieces in the wood to ship rather than lose packing them.  With my old hobby grade laser is took too long to mass produce so I never worried about it, but now I would rather produce them the way shown there.  That way small pieces don't get broken in shipping, and its easier to flat pack.  I have over 200 different files, each with different pieces to deal with though, and it can take 2-4 hours per to create them all manually. I just thought surely there would be a way...

Offline brynn

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Re: Help adding connectors to an SVG for laser cutting
« Reply #5 on: January 11, 2017, 06:03:47 AM »
If the pieces were relatively similar, pattern along path might work.  But I don't see how it could work with so many very dissimilar paths.  Not unless you could make sets of similar pieces, and have a custom pattern for each set?

If you use a different version of Inkscape at work and at home, that could account for the difference.  Because with the new 0.92 stable, it has a different native dpi, from all previous versions.

Oh, I see.  There's a good chance you're not going to like this analogy, but you're sort of making doll-house kits, right?  Or there's another hobby where people make just miniature tableaus, like historic houses, or something like that.   (I saw something on tv once about someone who made....was either Thomas Jefferson's or Thomas Edison's home in minature.  Inside and out!)  I'm not familiar with those games, and I had no idea that people actually built tiny worlds to play in.  I thought it was all played on the internet. That's amazing!

You still didn't say how you are creating the paths to begin with.  So I'm guessing that you already know that there's not any way to add the extra nodes during the original creation of the paths.  Or maybe you're not even creating them yourself.

So moving on to the possiblity of an extension.  It seems like this kind of feature could have uses in all different kinds of cutting - from your project with wood, to even something like paper dolls, or vinyl cutting.  So it could benefit some different user groups to have such an extension.

There's a small chance you might be able to find someone who would make an extension for you.  There's a much larger chance of that happening, if you could pay someone to write such an extension.  The Inkscape project has some new funded development guidelines:  https://inkscape.org/en/support-us/funded-development/.  So if you didn't want to pay out of your pocket, you could set up some kind of crowd funding or other similar fund raising.  It might not even need to be market value.  Sometimes just a token paycheck is enough for open source projects.

Whichever way you might want to go, I would suggest posting on the main Inkscape forum (inkscapeforum.com) and also posting to either the development mailing list and/or users list:  https://inkscape.org/en/community/mailing-lists/.  You'll need to fully explain the problem, and including all the parameters, such as what you mentioned about not having the tab lie in a corner.  The more details you can include, the more likely someone will become interested.  (I can't tell you how many times I've seen a message like - "I need an extension for this."  And that's all they say.  You can't blame any programmer for not wanting to bite on that.)

And who knows.  In those places are more advanced Inkscape users than me.  They might even be able to come up with a more automated way to do it, without an extension, that I just never thought of.  There are some new LPEs, and I haven't even learned what all of them do.  Maybe one of those could work?

Oh, and before you do that, you might want to try visiting http://www.cnc-club.ru/gcodetools.  It's an English section on a Russian forum.  And the admin is the author of all the gcodetools extensions.  Since they deal with a lot of different kinds of wood cutting, they might know of a solution.  If they happen to already know of an extension, let me know, and I'll make sure it's known to the whole community.

Note that it can be quite frustrating to visit, because instead of having a board for English topics, they put all the English messages in one topic.  It's really crazy, and extremely hard to find specific info.  The last time I was there, I didn't even bother searching if the question was already answered.  I just posted my question.  Who wants to read through 40 pages, or 60, or whatever it is, by now.

Let me know if you have any more questions.  Good luck!  :)
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