Useful Plasma Thread

Hi,

I have also tried the G.. tool offset's in linuxcnc with a simple dxf object. It was not very easy to do and next problem is
to define the lead in and lead out's. So i stopped at that moment.

I have tried Inkscape gcode a few times, but i need some help. Tommylight, can you make a tiny document how you program a dxf drawing to g code with inkscape? That would be usefull. Also included with your latest menu path>combine issue. I assume it's the
same as converting a drawing or path to polyline?

Today i made the auto restart function. I will test this function on the machine this week. This function set's the machine 25-30mm back on the cutting path and restarts with the full probe or non-probe procedure again. The restart attemps the user can select.
Also added the pierce speed and the probe speed parameters to the code, and implemented the adaptive speed into the c component. When not enable the adaptive speed is passed trough.

A sample code that i will try at the machine, and if not working good, i can modify it directly at the machine and try again.
@Islander :

I bet Nick can produce a nice solution if he wants to.

Yes i saw his inkscape solution, it's not finished, the project is half open. So if we look good at his python code,
we can make it complete and finish it.

We don't need the cutting speed, etc from inkscape. We use excel tool libraries with everything in it. We only need the M3 and M5. Lead in and lead out.
Autonesting module for python we can make later on. My feeling say's that i can better produce a nesting module in c language.

Grotius

Yes, I have hacked Nick's python code to produce nonRS274 code to run my non RS274 mill. I have never tried to use a offset with Gcodetools. Yes I agree we don't need cutting parameters from Inkscape. I am not looking for an automated nesting solution like Pronest just a way to manually nest multiple parts while only defining the cuts once for the first instance of each part? Look at the work flow in SheetCAM.

Tommy

Thanks, I am aware of the problems that can happen if you don't have continuous lines. I am very careful with my drawings to make sure that each path is a single object. I did a lot of work trying to get rid of witness marks when I worked out my corner hold component because I thought it was causing the marks. That is when I found out that the motion.reqested-vel pin does not reflect the contents of the active F block but the speed the TP thinks the machine can move at. When I fixed that problem the witness marks still where at several locations. On further investigation I found they are at code locations perfectly described by the bug tracker.

github.com/LinuxCNC/linuxcnc/issues/447

and

github.com/LinuxCNC/linuxcnc/issues/426

I am sorry but I do not have the coding skills to tackle either one of these bugs.

John

Hi John,

I will do the greetings to Nick from you at the Russian Federation.



John :

I have hacked Nick's python code

This is the boss of linuxcnc not of russian federation :



He looks like enjoying the Sun.

I think we need a new boss. Linuxcnc needs more update's.

I am awere of tunneling devices on linuxcnc preemt rt, server type instruments.
The one with the bird on github is dangerous. He eat's me at once.

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

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