Random laserengrave artifacts

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Random laserengrave artifacts

Postby 3d0g » Mon Oct 15, 2018 2:50 am

Seeing some glitches in engrave jobs every once in a while. It's definitely not in the image as I can re-run the job and they'll go away. At first I thought this was maybe some sort of signal noise / interference but I happened to catch this one today on the large 'P' and it definitely engraved incorrectly in both directions. There's another near the 'i' in Association as well. Any ideas? (click here for full size version.)

Image
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Re: Random laserengrave artifacts

Postby cncdrive » Mon Oct 15, 2018 3:12 am

Yes, it looks like noise on the control pin probably the wiring picking up noise or maybe the laser electronics picks up some noise.
I think it is noise because this type of issue was never reported by anyone and we did not touch those laser engrave routines for years and I know that lots of people are using the laser plugin without issues.
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Re: Random laserengrave artifacts

Postby 3d0g » Mon Oct 15, 2018 10:02 pm

While certainly not impossible, noise is improbable as like your untouched laser engrave routines, my laser hardware hasn't changed in many years and I never experienced issues like these with LinuxCNC. All my cables (except the short CNCdrive provided ribbon cables) are shielded and grounded. All power supplies tie to a common ground etc. I would also expect true signal noise to show up more frequently and randomly than what I'm actually seeing.

I ran quite a few test engrave runs today and focused in on what *has* changed in my system: going from LinuxCNC LPT control to Ethernet via the UC400ETH. Tell me if this sounds crazy... I disabled everything but IPv4 on the dedicated interface to the UC400ETH and removed that interface from Windows Defender Firewall control. After making these changes, I've had two perfect etching runs. Before these changes I had 6 runs all with minor artifacts. Coincidence or could I be on to something?

Cheers.

Oh, where can I make feature requests for future releases? I'd *love* to be able to enter pre and post g-code commands for etching runs, as well as temporarily set backlash to work around that little issue laserengave has. Lastly, some sort of feedback that the plugin is done sending the code to UCCNC - I'm never really sure when it's done and safe to close the plugin.
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Re: Random laserengrave artifacts

Postby cncdrive » Mon Oct 15, 2018 11:25 pm

I did not say that the computer or your Windows installation or configuration cannot have problems. I just said that in my opinion it is noise, it was more likely from the symptons.

The laser plugin is not making g-code and will not make g-code because it would be a large waste of memory.
Now one pixel is stored a single byte and if a g-code was generated then usually one pixel would take one line of g-code in avarage.
It might not sound a problem with todays's computer memory sizes, but in reality it can with very large images.

What do you mean "temporary" set backlash? Please explain how you want to do that and maybe my collegue can help you to write a macro for it.

OK, I'll check the Closing of the plugin to see how it exactly works now and will see if I can do something about it.
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Re: Random laserengrave artifacts

Postby 3d0g » Tue Oct 16, 2018 4:10 am

cncdrive wrote:The laser plugin is not making g-code and will not make g-code because it would be a large waste of memory.
Now one pixel is stored a single byte and if a g-code was generated then usually one pixel would take one line of g-code in avarage.
It might not sound a problem with todays's computer memory sizes, but in reality it can with very large images.


Of course. OTOH, What does happen between UCCNC and the UC400ETH is a bit of a "black box" protocol-wise. From just looking at network diagnostics, a substantial amount of traffic is passed during an engrave, which lead me to focus on that angle as a potential source of the problem.

cncdrive wrote:What do you mean "temporary" set backlash? Please explain how you want to do that and maybe my collegue can help you to write a macro for it.


Recall my previous post. To get crisp engraves, I have to add 0.02" backlash to the x-axis, even though my machine uses GT2 belts and has none. If I forget to clear the backlash from the x-axis config after the engrave, my next cut gets ruined. Being able to set a temporary backlash during the engrave would take an error-prone step out of my workflow.

Cheers.
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Re: Random laserengrave artifacts

Postby 3d0g » Wed Oct 17, 2018 2:10 pm

Few more engrave runs done - all glitch free. Fingers crossed, but it's looking like Windows Defender may very well have been the culprit.

Please keep my wishlist in mind for future releases.

Cheers.
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