Area Inkscape Gcode extension & artifacts

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Area Inkscape Gcode extension & artifacts

Сообщение MarkU » 02 апр 2011, 06:58

This extension is great - I am just learning but I think I will really enjoy it - thanks for making it.

I have a question about the Area extension...I will include example files inline...

When I use the area function to mill out a shape I get some missed areas. For example, in Inkscape I make a rectangle, 25 mm wide x 15 mm high at 5 mm X, 5 mm Y position. I subtract from it a circle, 5 mm in diameter a bit offset to one side. So now I have a box with a hole
initial shape.svg
(2.05 Кб) Скачиваний: 740
I want to mill this out so that I have a rectangular recess with a round post in it. I set tool diameter to 2 mm, and run the Area extension with "Area width" set to 50. I get a bunch of paths, plus a dynamic offset box on the outside (multiple copies), which I have to delete (I am curious about this but it is not my main problem)
paths inset.svg
(47.88 Кб) Скачиваний: 652


I then select the actual paths, and run Path to Gcode, it gives me the nice colours etc
paths coded.svg
(42.61 Кб) Скачиваний: 646
and exports the gcode
Gcode.ngc
(2.95 Кб) Скачиваний: 592
So far, so good. But, when I run the paths through a visualizer (in my case cncSimulator), I notice that the paths leave some chunks of material untouched that should be milled out - especially in corners where the linear outlines inset from the outer border meet the curved lines inset from the circular interior hole
Area Inkscape Gcode extension & artifacts Simulated.png
Code is used as it comes out of the extension, but I add "T5" as the first line to specify a 2 mm diameter cutter from my library. Visual examination of the last block of Gcode (which makes the outermost cut) shows it is correct to within rounding error for a 2 mm cutter. If I set width to 2 mm under Stroke Style in Inkscape, I see the same gaps, so this is not an artefact of the cncSimulator but a problem with the actual gcoded paths.

It looks to me like what is happening is that there are places where the logic cannot mill out the material without part of the cutter intruding into an area that has already been milled, and so it does not do this. Possibly this is a result of re-using the code that decides where the first boundary is to select subsequent milling paths? (e.g. the initial boundary path must not cut outside the desired area, but subsequent paths can exceed their target area and overlap with previous cuts, as long as they don't go outside the original boundary). Is there a way around this behaviour?

Thanks and I really appreciate you making this available, I will have a lot of fun with it once I figure out how to use it.

Mark
MarkU
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Re: Area Inkscape Gcode extension & artifacts

Сообщение Nick » 02 апр 2011, 13:46

Yes there are some things about that.


First of all if you want to see what will be actually cut you can do it straight from Inkscape. Select all the path's that are forming the trajectory, open fill and stroke dialog (Ctrl+Shift+F), go to the third tab, and set up stroke width equal to your mill's bit width and set up the corners and ending to "round". So thus you'll what will be actually machined.

How to avoid those uncut places

There are some improvements have been made in the Gcodetools-dev version. An overlap parameter has been added to standard Area function. Which defines cutting trajectory overlapping. It is useful to reduce amount of material that is cutting in same time (so you can use weaker routers) and helps to get rid of places.

Then a new function has been involved it fills the path with spiral or zig-zag. There wont be any uncut places and it works without "area artifacts" which are suddenly appear when using path-offset to create area curves.

I highly recommend you to try the dev version.
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Re: Area Inkscape Gcode extension & artifacts

Сообщение MarkU » 03 апр 2011, 05:28

OK, I will, thanks very much! Can I just dump the dev version into the Inkscape extensions folder & let it overwrite whatever it needs to?
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Re: Area Inkscape Gcode extension & artifacts

Сообщение Nick » 03 апр 2011, 11:17

To install dev version:
1. Get the files from http://launchpad.net/gcodetools or by bazaar "bzr branch lp:gcodetools"
2. Run "python create_inx.py"
3. Copy all files except create_inx.py into Inkscape's extensions directory. There should not be any overwrites because all files in the dev version have "-dev" suffix.
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Re: Area Inkscape Gcode extension & artifacts

Сообщение MarkU » 04 апр 2011, 04:39

OK, great - that seems to work fine, I get very nice cut paths out of it. Thanks!

Some unexpected behaviour I noticed:

1) When I run the area tool, as I mentioned before I get some "extra" outlines actually on the perimeter that are not tool paths. I checked and the number is equal to the difference between the number of tool paths needed to fill in the space, and the number I put under "Area width". So with 0.5 overlap, it will use 7 tool paths to mill the initial shape file (same file as above). If I set "Area width" to 10, an extra 3 outlines are made at the perimeter (both outside and around the inner hole). These result in the cutter running along the edge of the area, so the result is 1/2 cutter width "extra" is cut out at all edges. Not a problem as long as I set the "Area width" exactly to the right number though, only if I make it too big.

2) Once the area tool has run, if I select the resuling paths and run "Path to Gcode", I get an error message:

Warning: One or more paths do not have 'd' parameter, try to Ungroup (Ctrl+Shift+G) and Object to Path (Ctrl+Shift+C)!

- this is repeated 7 times, one for each path line, and the output file contains no gcode. However, if I copy the paths and paste into the same location with ctrl-C then ctrl-alt-V (no other manipulations), Path to Gcode runs normally with no error messages and produces good output.

3) If I run Path to Gcode with cutting order "Subpath by Subpath", the coloured paths generated look normal, but the actual gcode output contains 7 replicates of the edge-most path, and no cuts in between (so it mills the perimeter correctly, but does not mill out any other material). This does not happen for "Path by Path" or "Pass by Pass".

4) Setting units to "in" instead of "mm" under Preferences does not seem to have any effect.
Edit: I think I have figured this out, it seems the measurement scale is in inches if the "Orientation" scale is in inches - is this correct?

So thanks very much - it is working for me now - hopefully the above information will be useful to you.

Thanks!

Mark
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Re: Area Inkscape Gcode extension & artifacts

Сообщение Nick » 04 апр 2011, 09:27

1)...

Yes I know about that but can not do anything to solve the problem :(.

2) Once the area tool has run, if I select the resuling paths and run "Path to Gcode", I get an error message:
Warning: One or more paths do not have 'd' parameter, try to Ungroup (Ctrl+Shift+G) and Object to Path (Ctrl+Shift+C)!


When you run Area function, Gcodetools does not actually offset the path, it just creates Inkscape's "Dynamic offset" objects. Those objects are not Paths, but to be compatible to SVG format Inkscape adds parameter "d" which describes them as a regular paths. But Inkscape itself does not need this parameter, so sometimes it does not add parameter "d" until you do something to the path.

The easies and the most correct way is to use "Object to Path" from "Path" menu. Object to path does not work with groups so you'll need to ungroup objects or go into groups doubleclicking on them. Just do what the warning says :).

3)...


Can you attach your SVG? I need to test it.

4) ...

Orientation points are needed to determine scaling, positioning and rotating. And units under Preferences defines output G20 or G21 gcode and output scaling.

Thank you for the feedback :)!
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Re: Area Inkscape Gcode extension & artifacts

Сообщение MarkU » 04 апр 2011, 20:50

RE #3 - here are the files:

The paths laid out - you should be able to run Path to Gcode straight from this:
paths1.svg
(24.67 Кб) Скачиваний: 800


And the outputs I get:

PathbyPath_0001.ngc
(3.32 Кб) Скачиваний: 605


and

SubpathbySubpath_0001.ngc
(4.46 Кб) Скачиваний: 560


Windows 7, 64-bit, Inkscape 0.48
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Re: Area Inkscape Gcode extension & artifacts

Сообщение Nick » 04 апр 2011, 22:02

I think, I've fixed it. See gcodetools-dev revission 191.

Many thank's for the bug report :)!
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Re: Area Inkscape Gcode extension & artifacts

Сообщение MarkU » 05 апр 2011, 21:20

Working!

thanks very much
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