need help with X7 engraving settings

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

need help with X7 engraving settings

Postby ChrisBorg » Fri May 19, 2017 8:03 pm

I'm struggling with variations in engraving depth (using black and white bmp files - the engraved sections are solid black). In sections of the artwork where the laser is on continuously, the engraving depth will be half that of other areas. So straight horizontal sections are much shallower than other sections of the engraving. I'm engraving rubber stamps, and this creates high spots which pick up ink when printing.

I suspected it might be due to the laser changing speed before turning on an off, so I tried both the "Slower Params" and "Fastest Params" under the user parameters, but I got the same results from these and my original settings. I see this across numerous other settings (including engraving speed, Scan gap, Grade engraving on and off) and the problem is still there.

Solving this is critical for my application, so any help is appreciated!

Techgraphix
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Re: need help with X7 engraving settings

Postby Techgraphix » Sat May 20, 2017 3:50 am

It seems to me that the laserpower is collapsing due to insufficient power of the supply, during longer firing. It also can be the tube to be unstable.
You might try the following:
Set your black to a grey (about 75% grey), dither that (something like Floyd Steinberg) and engrave that. Your laser will turn on and of continuously, giving you a more equal surface.
I use it to give a much more equal engraved surface when i laser Acryl signs or glass.
The laser should be at the right speed when starting to engrave. Maybe the setting for acceleration is higher than the machine can handle but i expect you would get missing steps (when you use normal steppers without feedback)
In case of servo's or closed-loop-steppers there could be some dwell when you get it to extremes..
Kees

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Sat May 20, 2017 5:02 am

Thanks, I'll try the grey engraving idea and see if it helps. Is there any way to diagnose whether there is a problem with the laser tube or the power supply?

Techgraphix
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Re: need help with X7 engraving settings

Postby Techgraphix » Sat May 20, 2017 6:52 am

ChrisBorg wrote: Is there any way to diagnose whether there is a problem with the laser tube or the power supply?

Not that i know, other than replacing the one or the other. I don't expect you to have and use specific HighVoltage equipment to measure something.
You might see the currentmeter dropping, but i think it goes too fast and if the current drops, i can't tell you if it is the supply or the load..

Replacing the tube is the most logic:
- it's more likely that the tube is getting worse over time. (how old is it, in effective lasertime?)
- A tube needs to be replaced anyway, when it is worn.. so if this doesn't solve it, you still have a tube spare which you will certainly need.

Oh, first check all wiring first.. A bad contact to GND can also introduce similar strange behaviours..

Kees

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Sat May 20, 2017 7:01 am

test_pattern_s.jpg


This picture is a test pattern to illustrate the problem. The rectangle is 3 in wide (75mm), and the bottom pattern is the original file. Engraving depth is 0.05" between the squares and 0.025" above and below them.

In the top pattern, I tried Techgraphix's suggestion and added noise to the black area in Photoshop to turn the laser on and off throughout the engraving area. With this, I'm measuring 0.045" 0.035" in the two areas. So it does help reduce the depth difference. It does add roughness to the edges so I'll have to use it in selective areas as a workaround.

I would still like to resolve the hardware issue and any troubleshooting suggestions are appreciated!

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Sat May 20, 2017 7:11 am

The tube is new. This is a K40 conversion, and I never ran this machine with the original controller. I do have another K40 with the original controller, so swapping parts is feasible. I never saw problems like this on the other K40, but the control scheme for the power supply is different.

I could borrow the high voltage measurement equipment (and electrical engineer friends who know how to use it better than I do!) I guess I would need an oscilloscope and high voltage probe?- but it might be faster to start with swapping parts

Techgraphix
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Re: need help with X7 engraving settings

Postby Techgraphix » Sat May 20, 2017 1:23 pm

I had similar effects when my first tube was at its end..
Although your tube is new, it can be a bad tube..
When you reduce the speed and lower the power you could monitor the current between the blocks and the whole distance..
Not sure what to expect but i think the current should be te same.. If so, i would go for the tube..

Kees

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Sat May 27, 2017 4:26 pm

Well after swapping parts all day, I'm no better off.... first I replaced the power supply and got the same result. Then I replaced the laser tube with no change. So that brings me back to the controller (this combination of power supply and laser worked with the previous controller without this issue).

Any other ideas? Marco?

Tech_Marco
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Re: need help with X7 engraving settings

Postby Tech_Marco » Sun May 28, 2017 10:15 am

I think you may have setting issue especially the acceleration setting!

Please post a screenshot of your parameters setting for review
Also, tell me more about your machine. Post images of your machine as well. It is much easy to help troubleshoot with detail information

Marco

ChrisBorg
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Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Tue May 30, 2017 12:03 pm

After lots trial and error, I suspect my power supply(s) is the issue. I can eliminate the problem by dropping the power down to 50%. The level I need to drop to varies with the artwork. At about 70% or so, it works fine for a few passes and then I lose engraving depth. Maybe it's a thermal issue and I had fewer problems in the winter when the room was colder?

I'm ordering a new power supply to rule this out - worst case I have a good backup! If that doesn't help I'll be back and post all of my settings. Thanks for the help

ChrisBorg
Posts: 14
Joined: Fri Nov 25, 2016 6:57 pm

Re: need help with X7 engraving settings

Postby ChrisBorg » Mon Jun 05, 2017 8:35 pm

Well I think I finally found the problem - and it wasn't the power supply! So now I have two spares hammer

For all of my tests I was using a PPI setting for engraving. The problem goes away when I TURN IT OFF! After so much frustration, I'm curious why this happens. I was using PPI because it made my engraving surface smoother and seemed to improve resolution (I actually thought it was a resolution setting initially). Now I've read that PPI is primarily intended for vector cutting instead of engraving, and some software ignores it during engraving. Others use it during engraving.

So why would it engrave more deeply in some sections than others? I tested PPI settings of 300, 600, and 1000. I had different engraving depths, but the long straight areas are always more shallow. Firmware bug? Something really strange with how the laser tube handles pulses?


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