Tangential knife: rotation limit of -360 to 360 degrees

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Tangential knife: rotation limit of -360 to 360 degrees

Сообщение felixbeck » 10 ноя 2014, 00:02

Dear Nick, I'm using LinuxCNC, Inkscape and gcodetools in order to cut polyester fabric with a tangential knive on my self build CNC-machine.
I use different kind of knives to cut. One of them is a hot-knive which melts the fabric while cutting. This tool has a cable and can therefore be rotated between -360 and 360 degrees.
Unfortunately, gcodetools produces values for the A-Axis which are 'infinite'. I've seen values greater than 500. Is it possible to limit the values in the range of -360 to 360 by setting the tool parameters?
Please find attached the corresponding incscape and gcode files.
Thank you very much, with best regards, Felix
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Folie Teil 1 Incscape offsets.svg
(809.8 Кб) Скачиваний: 312
Folie 1.ngc
(53.43 Кб) Скачиваний: 190
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Re: Tangential knife: rotation limit of -360 to 360 degrees

Сообщение Nick » 12 ноя 2014, 09:56

You can do the following:
We assume that your paths is closed => has one full turn => it will fit -360 +360 degrees.

Now all we need is goto 0 after each path and start over the next path...
You are using linuxcnc - you are lucky because we have a lot of ways how to do it :)...

===============
hmmm that appears it's not so easy :(. It would be easy if you got -720 +720...
=======
ok another solution.
The thing is that you need all your paths to start at the left side of the path.
So select all your paths, add stroke 20px, add "Marker start" as something big and notable.
If it to the right of the path, use node editing (F2) select one of the nodes to the left and press Button (one node)-to-(two separate nodes).

And then check the Gcode.

PS if you put A axis limits into ini of the linuxcnc - it will check the Gcode automatically.
Use the Console, Luke.
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Re: Tangential knife: rotation limit of -360 to 360 degrees

Сообщение felixbeck » 17 ноя 2014, 01:46

Hi Nick,

thank you very much for your suggestions and ideas!
You are right incscape with gcodetools is very powerfull and flexible!

Meanwhile, I wrote a piece of software which postprocesses your generated G-Code from gcodetools to make it fit in -360 to 360.
I also replace G01 by G00 for A-axis rotation to speed up turning and insert Z-Axis lifts if the rotation is e.g. greater than 15 degrees in order to allow the use of a rotary cutter and to improve cutting results with the hot-knife.

Cutting results are perfect!

The tool was developped using Qt (C++). This was my first work with Qt.
As soon as I find out how to compile the tool to run without Qt I will post it.
until then please find attached the code and a screenshot.

Thank you very much again for writing gcodetools.
It became an very important tool in my tool-chain!

Best regards,
Felix
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mainwindow.cpp
(15.94 Кб) Скачиваний: 274
Tangential knife: rotation limit of -360 to 360 degrees Screenshot.png
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Re: Tangential knife: rotation limit of -360 to 360 degrees

Сообщение Nick » 17 ноя 2014, 10:03

Wow! Cool! :)

By the way if you can make a cli (Command line interface) for your program it can be easier to use with LinuxCNC.
I.e. add parameters like --a-axis-g0 --insert-zlift and so on, and output Gcode to standard output - then it can be used as a FILTER.

Or just add standard output, and you will be able to use FILTER of LinuxCNC http://linuxcnc.org/docs/html/config/in ... ER-Section then you'll see your window.
Use the Console, Luke.
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