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Jeff Body
08-17-2016, 1:11 AM
CM6000 paste sprayed from an airbrush
Does anyone recolonize this problem?
I'm pretty sure I had a nice even thin coat on but I'm getting these brown strips in my solid black areas.
It's not scrubbing off so it adhered well.

What could of caused this?
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Kev Williams
08-17-2016, 2:10 AM
it's not just the Cermark, it's your laser. The brown goes thru the bird's wings, and also thru the 'c' in Beach, a full sweep thing, and specific in it's placement...

And you're not alone... I lasered this yesterday and today, it's a 24" x 30" stainless operator panel. Frankly, I'm disgusted with the large lettering (about 2-1/2" tall)

Notice, mine is doing much the same thing as yours. But my machine is taking it a step farther; where your mis-markings are lined up with X axis, my mis-markings are traveling diagonally downward. This lettering is running diagonally up hill. What happens is the X start and end points keep changing places as the 'dead space' changes. That's all find & dandy, but why does that affect the engraving?
And notice how the markings line up with each other in the A and C, and the S and K? This is pretty funny because each letter is etched individually, and each letter is done as far from the last letter done, so as to keep heat buildup in one area to a minimum. Even so, the weird markings line up. So it's not really 'accidental'. The machine is sorta doing it on purpose. BUT WHY!?
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Answer: I have no clue. I've convinced myself it's just the nature of trying to laser Cermark with a DC laser.

Now, notice "TRAC" looks okay, and "SKY" looks horrible. Just the lighting angle. Actually, straight-on, it looks fine. But it's not going to be looked at straight-on all the time. My customer, luckily for me, has no problem with this.
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Notice "SKY" is now nice & black looking, just change the lighting a bit...
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I'm actually quite surprised that most of you guys with glass lasers get pretty good Cermark results with them. This Triumph I'm absolutely pleased with everything it does EXCEPT Cermark. Now, notice these 2 pics, you will notice that in both pics, the "touchscreen" lettering is very much blacker than the 'skytrac' lettering. This isn't a lighting trick, I purposely tried to even out the lighting on for these pics, on 2 angles...
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The reason for the blacker lettering is simple: I engraved THAT lettering in my Synrad-powered Explorer, the other lettering the Triumph did. (The Explorer also did the 'Christmas Mountain' logo and all text below the Skytrac logo that's not seen) All 3 RF lasers I've owned do a 1000% better job on Cermark than my Triumph. And for the life of me, I really don't know why. Obviously something about the beam itself.

I CAN get a blacker mark on the Triumph, it simply involves using less power. Problem is, just about the point where the mark is satisfactorily dark enough, it won't stay on the stainless, a magic eraser can wipe it off. Coversely, the 'touchscreen' lettering will take several minutes with 80 grit sandpaper to get that off.

While I'm typing this, I'm running a power grid test- again- with the Triumph.

Why do I use the Triumph when my metal lasers do a better job? Time. Especially on these panels, which have miles of vector outlines to engrave. The Triumph does fairly well with those. The Triumph will also do those large letters much faster. Now, if I want a nice consistent mark on those big letters (and everything else), all I have to do is crank up the power. (This panel was done at 28% power) Adding power results in a wonderful mark, totally devoid of funny brown patches, very consistent. Problem is, the mark isn't black. It's more of a semi-dark gray with a bronze hue to it. Looks okay, but in bright light, it almost disappears. So right now I'm testing again. One thing I'm doing different than in the past, is tightening down the resolution, to .04mm Makes it slow, but if it works, I'll take it. :)

Anyway, I feel your pain. I'm not sure why yours even did that, but it does appear there was a bit of a 'burp' where it started, on the one left edge.

In summary, I had the same problem with the old Cermark, just not as noticeable. The new Cermark is definitely different. But it's not all its fault, it's a glass laser thing I'm afraid....

Keith Winter
08-17-2016, 9:12 AM
Kev is much more of an expert in this than me. He makes a compelling point that it could be something to do with using a glass tube laser so I would have to defer to his expert judgement.

However before giving up on your laser...
1. Try increasing the power/slowing down the engraving.
2. Try buying one can, instead of airbrushing. Your mix might not be right, if you go from the can it will definitely be correct.

Jeff Body
08-17-2016, 1:30 PM
Thank you very much Kev. I'm glad to hear I'm not alone.

I did use a different set of setting for this cup. I increased my scan gap to .042 which is about 600dpi and I didn't use any air assist.
When this cup was finish it was HOT and burned myself alittle touching the problem area too soon.

I have to admit I haven't been keeping track of my setting like I should be. I've been going up and down in both speed and power just trying different settings.
The very first cup I engraved I just copied a friend's setting and it came out pretty good.
Those setting where 150mm/s at 50% power and .08 scan gap.

I engraved a cup for myself this past weekend and tried a different set of settings.
I dropped down to 100mm/s and 65% power at .08scan gap. This turned out ok but if you looked really closely you can see lines of black in the engraved areas of the cup.
Almost looked like too much power but I'm not sure.

What does too much power look like?


Keith

I think I will try the spray can next time just to see if there's any improvement.


Thank again guy for the replies.

Gary Hair
08-17-2016, 2:25 PM
I have to admit I haven't been keeping track of my setting like I should be. I've been going up and down in both speed and power just trying different settings.

You really need to do a power grid to give you the optimal settings. 100% power, 600 (or higher) dpi, adjust the speed to get the desired results.


What does too much power look like?

Overpower will turn to a shade of tan/brown, similar to what you are seeing. Anything besides black and you have the wrong settings.


I think I will try the spray can next time

That won't change a thing, get your settings right and it won't matter how you apply the Cermark to the substrate.

Kev Williams
08-17-2016, 3:09 PM
Back when I first got the Triumph and was finding out the Cermark issues, one thing I noted is that it seems like the laser beam leaves a distinctive 'knife cut' edge on the Cermark along the beam path, it very much resembles looking at record grooves. My metal lasers beam path is visible but is much more subtle. Adding more power seems to actually vaporize the Cermark rather than fuse it to the metal.

Just ran 2 tests- pay no attention to the alignment on the LS900 test (my shim stops were taped down in the wrong place) ;)...
As it says on the plates, I ran the Triumph at 70% power, which is its 26mA max when vectoring, at 350 speed, which is pretty brisk for Cermark.
And just to try and burn off the Cermark, I ran the LS900 at TWO speed, which is creepy-crawler speed, normally I run Cermark at 16 speed.
The Triumph took 1:37 to engrave, the LS900 5:38...

But as you can see, the LS900 plate is a LOT blacker than the Triumph plate. .
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Here's a closeup of the 'record grooves' left by the Triumph. As you can see, the Cermark isn't fused to the plate. It's simply not there. Vaporized? To be sure, the mark is very consistent, and it's definitely permanent. It's just the least bit dark enough to suit me...
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The LS900's 40w tube running over this at about 20% the speed of the Triumph should have had plenty of time to torch the Cermark, but it doesn't. Beam path lines are visible, but they're not near as pronounced, and they're surrounded by fused Cermark.
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One way I've found to combat this problem is to use a 3" lens to engrave Cermark. Seems to help with the consistency and color. Running out of focus helps too, but I've never been able to get it consistent enough, main problem is lack of fusion, mark washes off...

Ross Moshinsky
08-17-2016, 4:33 PM
I've mentioned this to Kev more than once. I could be wrong but I'm fairly confident the issue with Chinese lasers is they are too slow to take advantage of the power. A 100W laser needs to run at ~80ips to mark correctly. Considering a Chinese laser maxes out at about 22ips, that means it theoretically needs about 30W of power.

I'm fairly confident if you ran your laser at 500mm/sec and 25-35W of power, you'd get a similar mark.