Useful Plasma Thread

Hi,

Today i made some artwork with linuxcnc and inkscape. It's a heat cover.
I am now 100% convinced i will use linuxcnc forever

That's pretty amazing, how much kerf does your torch have?

Hi,

This is done with hypertherm duramax torch. 45amp finecut. Kerf 0.95mm
Speed 1800mm/min 45amp. Watertable.
Cutting time about 70 minutes.
300+ starts

That is niceeeeeeeeeeeeeeeee !!!

I tested the autosize screen today on different older monitors, but the total height is a little to big. I will change this soon.

I was looking how to implement the cutspeed parameter.

In the past i tested the cutspeed adapted as variable's in g-code : forum.linuxcnc.org/38-general-linuxcnc-q...gram?start=10#105941

But now i think different. In the THC2 component we can say the following :

Max_machine_speed for example 19000 mm/min
That value can be used between M5 and M3 in the C code. This is actually the G0 speed.

Cut_speed_value = 2500 mm/min.
This value is used between M3 and M5.
We connect this to the component with : ini.x.max_velocity & ini.y.max_velocity

So in short lines Inkscape has only to produce a m3 and m5 and a cutting path with offsets, lead in and lead out's.

Okey thinking further. The external offset branche is made for making real time offset of +1mm tool kerf or -1mm tool kerf on x or on y axis, but how will we do that in circulair way objects? This must be tested.
If this is a solution, we only have to make clear if it's an inside or outside offset cutting pat'h.

Look at this video :
Time 1.37 minutes. So it can work !

Okey thinking further.
Automaticly recognition of contours is nice. The most outer contour is 99% of time the outside offset. The rest is 99% of time
inner contour, inside offset.

g0 x100 #1 (inner contour offset)
g0 x100 #2 (outer contour offset)
g0 x100 #3 (no contour offset)

This function in not available for open path's at this moment. But we can make it if we want to.

It looks like a g-code pre-processor combined with a g-code end-processor for inner, outher an no contour offsets.

Grotius

You are at the really hard part for a good PP. We all know the mathematical definition of an offset line but it really can get difficult when you are dealing with compound curves. Getting the ends of the individual arcs to co-inside in a predictable way is not easy. Usually the endpoints of the arc must be changed or small linear segments added. This is further complicated when you have a SVG file with Bezier curves defined. This is where one low cost CAM program really falls down. It produces nice code when following the path in the drawing file but really produces funny code ( lots of .001" moves) when doing offset paths. The way I would approach this is to look at how Inkscape does offset paths. It is open source so the code is available for inspection. The offset paths in Inkscape end up being quite well behaved.

I can only offer my best wishes for your success in doing this as the math and coding are far above my skill level. In the past when I only had Inkscape and Gcodetools I found that in the end it was usually quicker to just make every path an open path and manually add any needed leadin and leadout. I did this because I never did figure out how to force Gcodetools to put the leadin/leadout pair at a predefined node. I would also do all my offsets using either the Inkscape Transform/Scale commands or the Path/Inset or Offset commands. This is quite cumbersome but produces good cut able Gcode using Gcodetools.

John