How to create a path for CNC hot wire cutting

[syntesilab]

Hello everyone,
do you know if there is any extension or trick to convert a design into a path optimized for hot wire cutting foam with a CNC machine?
Paths for hot wire cutting are a single and continuous path which goes along the whole design connecting all separated paths.
For example, if I have a "O" letter, I should obtain a single path going along the external ring, then continuing by going towards the internal ring and finally going along the internal ring.
I've searched everywhere but it seems this function doesn't exist.
Could you help me with this issue?
I only know there are standalone softwares, but they don't allow to edit and save .svg paths, they only generate directly g-code, and only for a few models of machines.
Do you know if I can use Inkscape for converting a number of disconnected paths into a single and continuous path?
Thank you.

[brynn]

Welcome to the forum!

Oh gosh!  I didn't answer your message yesterday, because I don't know much about your application.  There are ways to connect paths (of course) but it depends on the specific file as to exactly how you would go about it.  Can you share a sample file?  And if they are dissimilar files, maybe share a couple.

Oh wait....  Just when I thought my memory was going down the tubes, I don't know how in the world I remembered this.  And to be honest, I don't know if it's what you want.  But it has "wirecutter" in the name.  So maybe?

It generates gcode, but it doesn't sound like the same thing?  Also, being hosted on Sourceforge might be a bad sign for it's up-to-date-ness.

http://sourceforge.net/projects/wirecutter-inkscape-plugin

But if that's not what you need, please share a file or 2, and we can tell you how to connect paths (some ways are "manual" and some automated).

[syntesilab]

Thank you for your response.
Unfortunately that software seems not so good, because it directly generates G-code, while I would like to mantain my project as .svg in order to view and edit the final result, and finally send it to the software which controls the cutting machine.
G-Code files aren't universally recogniozeable by all the machine, and they could cause the machine not to work properly if the code isn't written well.
I've attached a sample image explaining the result I would like to obtain.
As you can see, it's all a single path going along the whole design. That's because, once hot wire enters the material to cut, it can't go out when "it wants", but it has to finish the cut in a single pass.
Above all, note the parts going inside the "o" and "e" letters, in order to cut the inner parts.

[brynn]

I would need to see the SVG file, to be able to tell you about joining all the path segments together.  Of course it can be done, there's no question about that.  The question is about the best way to do it, and I can't get the kind of info I need from that PNG file.

[syntesilab]

Unfortunately I don't have the svg file (if I had it I would have solved the problem!).
This is just an image I took from the internet, which was created with a software called docado, but which generates the g-code directly and then it's not good for the reasons I explained before.
I was just wondering if there was an inkscape function to automatically create a single path, because it would be impossible to do it manually if I had a complex design.
But, at this point, I think it can't be done, also because by doing researches on the internet I found absolutely nothing that could be managed by Inkscape.
Anyway thanks for your kindness.

[Moini]

There is such a function... Two, to be more correct. But hey, the internet knows everything, of course.

[brynn]

Oooohhh, now I understand your question!  I didn't realize you had no vector file.

You could use the Centerline Trace extension.  It's an auto-trace engine which produces a single path.  You still might need to manually connect some parts here and there, and maybe tweak the paths a little bit.  But this will create the paths for you.

It might not work for a more complex design.  But I only say that because I don't have much experience with it.  It might work great, for all I know. 

Here's the extension:  https://github.com/fablabnbg/inkscape-centerline-trace

I think it has instructions for installing on that page.  But let us know if you need help.  I'll be glad to try.

I'm not sure what Moini is thinking about for the 2nd tool she reported. 

[Moini]

Nah, I got it wrong :/ . The user is correct. This must be figured out manually.

[brynn]

Don't you think Centerline Trace will generate the paths?  They still will have to be manually connected in places though.

[Moini]

Centerline is not what the user needs. They want to cut out shapes from foamboard or something with a hot wire, and cut out the holes and cut the contour in one continuous long cut.

[syntesilab]

Thank you for your responses, but Centerline Trace unfortunately is not what I'm looking for.
Maybe I badly explained myself in my last comments, when I talked about an image taken from the internet.
I don't need to convert an image into a vector line, I'm able to create my own design in InkScape directly by tracing it.
The problem I have is I start from a vectorial design I've created in InkScape and, when the project is finished, I need to have all my paths blended into an unique and single line which goes along the whole design, so it should connect near and separated paths with a segment and continuing like that all over my design.
In order to simplify things: If I draw two separated circles, I need a function which connects the two circles with a segment (maybe the shortest possible one) and converts all in a single line.
I apologize for my last comment if I've offended anyone; I didn't mean there is absolutely no solution and you can't help me because I've searched on the internet with no luck, I just wanted to say that I've searched a lot before writing in this forum (as anyone should do before making people lose their time with already answered questions, I think). And to me it seems very strange there isn't such a function, because I think after all it's nothing so extraordinary. It's just something like: connect all isolated paths with the nearest ones and merge all in a single line.

[Moini]

It is extraordinary. You're the first person ever who asked for an automatted solution for it. I assume everyone else just does that step manually.

[syntesilab]

Anyway, thank you so much everyone, I will search for any solution by asking to the VCarve Support, since this is the software which controls my cnc.
Best regards.