Banding Issue Speedy 400

[Jiten Patel]

Hi All,

Has anyone ever seen problems like this? I have getting thick banding when engraving acrylic. This is 3mm mirror and it is very distinct. It looks like the laser is putting out more power in some areas causing the engraving to be deeper?

Any help would be great.
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[Scott Shepherd]

Are you using "High Quality" mode? If not, turn it on for the color you are engraving.

[Jiten Patel]

Hi Scott,

Thanks for that - but doesn't High Quality mean that the carriage travels the entire length of the job size rather than the actual engraved area? We have tried this before but it took forever. These sheets are full bed size but are only engraved in certain portions. Almost impossible to line up using smaller jobs placed on the bed. This takes around 20-25 minutes, whereas High Quality would take around 60?

[Scott Shepherd]

Jit, it forces the travel to be the same size as the job. That, to me, is not a "banding" problem, it's a problem where the you have graphics all around different places on the sheet. It's hard to explain in a couple of words, but if you have 2 rows of text on the left, and 1 row on the right, as it engraves, it will put lines like that in your left hand text, where it starts and stops engraving on the right. It's the nature of what you are trying to do along with that material. It happens on all lasers that I know of. I've never seen one that it didn't happen on.

It requires you to rethink how you approach the job. If it were me, I'd setup guidelines in JCX, then I'd break up the text I have into however many piece you need to, send each job over as "Minimize to Job" with High Quality turned on. In your case, if you have 4 large areas of text, I'd send 4 jobs over, each one with one block of text. Then in JCX, I'd drag and drop them onto the plate, snapping them to the guidelines I put on the plate using the rulers. That way it's going to give you the High Quality engraving while still minimizing the stroke so it's not doing the whole bed. I might even color map a color or two if I thought that would help the speed.

I think you're just processing it wrong. You can fix that and it'll all get better :)

[Glen Monaghan]

No idea about Trotec, but on Epilog you'd color code the different areas and send as one job, which would cause each area to be engraved in sequence according to the color.

[Bruce Dillingham]

I had this problem and it turned out to be one of the power supplies.

[Scott Shepherd]

Take a look at the photo, the first photo, you can see where the motion system transitioned from a longer stroke to a shorter stroke. That's typical of not using High Quality Mode on this type of material. This type of material is VERY sensitive to that.

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[Kev Williams]

That makes sense, but it doesn't explain the banding on the exclamation point, which only appears on the dot and the LEFT edge of the outline but not the right edge. There's nothing about the exclamation point or any graphic engraved nearby that I can see that would contribute to a power transition. But then, I can't see the whole job.

What also concerns me is that the banding is reasonably uniformly spaced vertically: In photo 2 there's 3 bands, and they're nearly equal distances apart. In photo 4 the bands are different widths, but the spacing between them fairly equal. And all the bands in photo 5 are spaced equally...

I have to agree with Bruce that it may be a power supply/controller issue...

[Scott Shepherd]

That makes sense, but it doesn't explain the banding on the exclamation point, which only appears on the dot and the LEFT edge of the outline but not the right edge. There's nothing about the exclamation point or any graphic engraved nearby that I can see that would contribute to a power transition. But then, I can't see the whole job.

What also concerns me is that the banding is reasonably uniformly spaced vertically: In photo 2 there's 3 bands, and they're nearly equal distances apart. In photo 4 the bands are different widths, but the spacing between them fairly equal. And all the bands in photo 5 are spaced equally...

I have to agree with Bruce that it may be a power supply/controller issue...

It's simple, there's a graphic beside it that's causing that. I've seen it 100 times. Been there, done that. It's not power related. Our Epilog did it, our Universal does it, unless you have their mode to fix it turned on, and the Trotec does it if you don't have the mode turned on. It's easily fixable by turning that on and changing the way you sent the job over.

[Scott Shepherd]

I can walk to my laser right now and make this happen, so it's not power related.

Here's the issue that you can't see in the photo.
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[Jiten Patel]

Hi Scott,

I see where you are coming from, but I have been using this method for over a year, on hundreds of these jobs and never had anything like it which leads me to believe that it may be a fault. I see what you are saying could very well be the cause, but its odd that it has never happened before of very similar jobs (large engraving on mirror acrylic).

I spoke to Trotec and they think it may be a faulty power supply. I will naturally let you guys know what it is once the tech guys pay us a visit.

[Scott Shepherd]

It may be Jiten, but if you've been getting away with it for a while now, you've been lucky. I can replicate that on every laser we have, or have ever had. If it's the power supply, it's a very very minor power issue. The fact that it happens in the strokes is the tell tale sign for me. However, I can't see the entire graphic and I'm speculating on the placement of other items around it that are causing stroke changes. If there's nothing to the side of those areas and it's doing it, then I would agree it might be a failing part or a software bug.

[Jiten Patel]

Here is the complete artwork.
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[Scott Shepherd]

I can't see how you've done so many of that graphic not using High Quality and gotten acceptable results. I think you've been lucky. If I were setting that job up, I'd color map 3 areas, the left logo, the middle text area, and the small text at the right. I'd use high quality on all of them. It's easy to test my theory, take a small area of it that's causing you issues, and the text around it, and do a test on a 6" x 6" piece. If it solves the issue, then it's HQ related.

[Scott Shepherd]

I can easily see how the marks would get there....

Whether or not it's the issue, I don't know, but I can, logically, see the motion changes between letters causing that.

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