Odd behaviour with the Mini CNC

Discussion
1

Hi @CNCtechs/@CNCers,

TLDR: I had some odd behaviour with the Mini CNC so be extra ready with the EStop button when you start your job.

I was running a fairly long job milling some brass, everything was going great until the cnc machine just stopped, I hit the e-stop as I thought the bit might be bound up.

I checked everything and couldnt see anything wrong so I tried to re-run the job.

At that point I started having problems touching off on the z-axis, when I hit the start button it seemed like the z-axis would get re-zeroed at a seemingly random height. I was fairly quick with the e-stop so avoided any disasters :slight_smile:

I did a full restart of the system but still seemed to be getting the problem.

At this point I should point out that Im running gcode created by FreeCAD so its entirely possible that the problem is related to that.

To check I tried running some gcode I had created previously using v-carve and initially got the same problem but when I re-touched off for a second time it seemed to work fine.

This obviously does point towards a FreeCAD problem but its a bit weird that the same g-code was working perfectly prior to this mysterious ‘stoppage’.

I left a note on the machine with the TLDR on it.

If this problem rings any bells for anyone let me know.

It may be nothing but I just wanted to mention it just in case Ive broken anything and ill drop back in and give it another try tomorrow.

2

There was a problem once when I was cutting and the fob reader was causing the machine to cut out. Could this still be an issue?

3

@asander1 I think you said that the tool control might be causing this?

4

Thanks! I’ll have a look tomorrow. Let’s see. I had similar error on long job, it’s not new to that machine, but i haven’t figured why yet.

5

Thanks for the responses!

Ok great, good to know the stoppage wasnt something new.

Still not sure why I was getting the z-axis problems, possibly just PBCAK :slight_smile:

Like I say ill give it another try today.

6

Yes, it is the relay in the tool control! - nothing to do with the machine itself or your job, the relay needs replacing or changing to something else, it randomly cuts out and causes the machine to e-stop. Very annoying, we need to fix it soon!

7

I had another go yesterday and everything worked perfectly for me :tada:

I think z-axis problem was related to the gcode FreeCAD was generating gcode which turned on tool length compensation and the tool table in LinuxCNC has a z axis offset set for some of the tools.

I just changed all of the tools in FreeCAD to be tool #0 and that seemed to fix my problem.

Not sure why this was suddenly a problem for me. It seemed to totally coincide with the random stoppage, but I might have inadvertently changed something in FreeCAD. Ill have another look and see if I can make sense of that.

Anyway thanks for everyones input :slight_smile:

1 Like
8

I believe I did set the tool length to 0 in freecad, to avoid tool length compensation.