QTDragon operation notes

Hi all,

This is some feedback on my first cutting job using LinuxCNC – QTDragon GUI.

Firstly, I would like to thank those who made this GUI – it’s great, and I’m really warming to this interface.

I don’t fully know if the issues referred to in these notes are because I haven’t set it up correctly or, they are short comings or, bugs…

My machine was a CNCEST 6040, with a USB interface and Mach3. My initial step was to design and build a parallel port interface, which I did, and engraved it with Mach3. I installed it into my CNCEST Controller, replacing the USB interface.

I then installed LinuxCNC via the linuxcnc-2.8.4-buster.iso (as a dual boot). I then ran stepconf:-

Setting up the stepper motors was pretty easy, mainly because of the Test button. Also, having the computation results from the max speed, acceleration, pulse frequency etc was very helpful.

When it came to do the spindle – without a Test button, I went through that loop about 10+ times…

Looking at several GUIs, I thought that QTDragon would suit me best. I couldn’t find a configuration template for it, so I just manually added it into my INI file. Without adequate documentation, it was a trial-and-error process.

One thing that I really found annoying was, stepconf overwriting my changes. There should be more options about that in stepconf or, a custom INI file with additional settings…

My first cutting job – engrave a spare parallel interface board.

The NC uses probing to generate Z offsets, with 90 (10 x 9 grid) probe points. When running, I’d randomly get this Error - “Probe tripped during non-probe move.”, and the machine couldn’t complete the 90 probes. QTDragon didn’t help – the highlighted Gcode line is wrong, it would rewind back to the start on this error.

Sample GCode
...
G1 X41.16252 Y2.095 F1000
G38.2 Z-1 F5
G0 Z2
…

I changed the GUI to AXIS which showed the error was occurring with G0 Z2

I’m using the engraving tool as the probe (not spinning), and PCB is sitting on 1.0mm double-sided foam tape.

In this case, it should NOT produce this error. Also, it should NOT rewind the program – it should go to the Pause state allowing the Resume command…

Drilling the PCB – The software that generates the drill code embeds manual tool change coding.

I don’t have an automated tool changer, I need to do this manually. The code raises the spindle to a height for me to change the tool, but now I need to zero Z. QTDragon won’t allow me to move the Z axis while in Auto mode. When I change it to Manual mode, it rewinds the program!!!

The finished board is really good, and I’m very happy with it. Much better than the Mach3 board.

I hope the above info can be used to improve this product. And perhaps improve me too!

Kind regards
Pedro
 

There is actually a lot of documentation.
linuxcnc.org/docs/2.9/html/gui/qtdragon.html
also there is a number  docs on qtvcp under virtual control panels on the  main 2.9 docs page
linuxcnc.org/docs/2.9/html/

Thank you for the feedback.
I maintain QtDragon in linuxcnc - Another fellow user (Jim) designed it and agreed to allow it to be included in linuxcnc.

I see you are using 2.8 - this was the first inclusion of QtDragon - I think it was pretty good, but it has come along way from there in 2.9.

Usually the error message will tell you the approximate line number with the error. Did it not?

“Probe tripped during non-probe move.” is usually either electrical interference or the probe tripped from inertia of the rapid movements.
If this is the problem then it should error and end the program not pause.

The line roll back is probably annoying but it does show where the program will start if the run button is pressed (which would be line 1 after an error).

Some sort of 'last line run' indicator might be useful, except linuxcnc is never reliably exact with line numbers (it's a problem from a long ago implantation decision, not easily fixed)

linuxcnc does not natively allow jogging while paused and does not allow setting the origin while paused.
There are tricks to get around this.
One common one is to automatically probe the tool length on every tool change (needs a tool probe)
Another was a special toolchanger program that basically stopped the program at tool changes and then restarted the program after. (2.9 qtdragon supports this natively - I can't remember if 2.8 did and I haven't tested it in a while.)

2.8 probably won't get any updated releases.

Chris

Thank you for your reply.

There is actually a lot of documentation.
linuxcnc.org/docs/2.9/html/gui/qtdragon.html
also there is a number  docs on qtvcp under virtual control panels on the  main 2.9 docs page
linuxcnc.org/docs/2.9/html/

These were the two main documents that I used. However, there are several deficiencies in these documents, for example -

This input pin should be connected to indicate probe state.qtdragon.led-probe 

This is both lacking detail, and has an error. qtdragon.hal-led-probe is actual name of the LED, and there is a predefined NET named probe-in, which would be helpful.

[DISPLAY]
PREFERENCE_FILE_PATH = WORKINGFOLDER/qtdragon.pref 

WORKINGFOLDER - hmmm is that a variable defined somewhere else or, am I to replace with an actual path? But what path - is there recommended place - should it be privileged...

I hope this helps.

Kind regards
Pedro
 

Thank you very much for that informative reply @cmorley.

I think it was pretty good, but it has come along way from there in 2.9.

I'm still getting my head around the LinuxCNC versioning - is 2.9 the QTDragon or LinuxCNC version?
If it's LinuxCNC is QTDragon different from 2.8?

Usually the error message will tell you the approximate line number with the error. Did it not?

No line number, not that I could see. I had to change the GUI to AXIS to get the line number.

If this is the problem then it should error and end the program not pause.

The issue is - the G38.2 pushes the probe into the PCB (the PCB is sitting on 1mm foam tape, so it won't damage the tool). It may take several process iterations for G0 Z2 to raise the tool high enough to break contact with the PCB - it is not an error! Mach3 ignores the probe signal on non-probe moves.

Some sort of 'last line run' indicator might be useful, except linuxcnc is never reliably exact with line numbers (it's a problem from a long ago implantation decision, not easily fixed)

The AXIS GUI seems to track the lines numbers - perhaps some cut-&-paste is required...

linuxcnc does not natively allow jogging while paused and does not allow setting the origin while paused.

That is a big short coming!
My workaround is to separate the drill file into individual files for each tool - what a painful process...

2.8 probably won't get any updated releases.

Are you able to do anything about these issues in either 2.8 or 2.9?

Kind regards
Pedro
 




 

Another thing about QTDragon - with the message from a M0 code, the horizontal slider on the GCode panel is locked out, so you can't read all the message.

It would be great if the message could be presented in a floating dialog box...

Kind regards
Pedro

2.8/2.9 is the linuxcnc version.
2.8 is the current officially released version.
2.9 is close ish - it certainly can be used reliably.

I think you might be missing a library that pops up a message dialog.
If you run linuxcnc/qtdragon from a terminal, it might tell you the library names.
Something like package python-dbus.mainloop.pyqt5

Probing error - that should be a linuxcnc (not qtdragon) problem - sounds like your Z axes acceleration is low. Strange it would be different with AXIS.
There is another probe gcode 38.4 that moves away from the work piece and trips on loss of contact. so probe g38.2 down, then probe 38.4 up, then rapid up. probably more accurate too.
linuxcnc.org/docs/2.9/html/gcode/g-code.html#gcode:g38

There is no guarantee that the line numbers displayed are exact in linuxcnc.
often they are right, but not always.

It's possible to trick linuxcnc to do jog while paused with external offsets - it's a bit advanced but it still doesn't allow origin changes while in auto mode.
We almost had proper built in Jog while paused... but that was a long time ago.

What distribution of linux are you using? Debian? The floating error messages should work in 2.8 - probably just missing the package.
If you could run linuxcnc from the terminal and post the output, maybe I could see the problem.

Chris

Thank you for your reply.

2.8/2.9 is the linuxcnc version.
2.8 is the current officially released version.
2.9 is close ish - it certainly can be used reliably.

I think you might be missing a library that pops up a message dialog.
If you run linuxcnc/qtdragon from a terminal, it might tell you the library names.
Something like package python-dbus.mainloop.pyqt5

I'll look into the above when I'm back in the workshop...

Probing error - that should be a linuxcnc (not qtdragon) problem

I'm still working out where the demarcation lines are...

sounds like your Z axes acceleration is low. Strange it would be different with AXIS.

Oops! I didn't mean to mislead. I only switched to AXIS to get the error line number. When I found it was the G0 Z2 code, I found a workaround by playing with the Feedrate & Rapidmove override controls...

I can see how the G38.4 would help. I'll give it a go next time.

We almost had proper built in Jog while paused... but that was a long time ago.

Maybe that can be put back on the table.

What distribution of linux are you using? Debian? The floating error messages should work in 2.8 - probably just missing the package.
If you could run linuxcnc from the terminal and post the output, maybe I could see the problem.

I'm using Debian Buster (as supplied in the LinuxCNC ISO).
I do get the floating error messages.
I will run it again from the terminal to check its current state., when I get back to workshop.

I'm not a Debian guru. OpenSUSE is my flavour - either Leap or Tumbleweed.
I have done the odd Raspberry PI with Debian. But the last one I did was with Leap 15.

Kind regards
Pedro






 

I have run LinuxCNC from the terminal - attached are the logs.

Apart from the Error about the Basic Probe macro, I can't see any issues... Do you?

Kind regards
Pedro