Is this banding?

[Avraham Monina]

I got some macbook pro tops, I etched some random vector art on it (RGB black) and where there is alot (I mean not just line, like a solid circle like the photo) I see this banding looking effect which is no good, I am using 100 speed and 40 power( which is what epilog has for the iphone they etched on the website), is 40 too strong?
Thank you!!

[Scott Shepherd]

Yes, that's banding.

[Avraham Monina]

I was under the impression that banding only happens in images and not in vectors art? I know with photos you need to match the DPI for it not to band, what about vector art?


Yes, that's banding.

[Scott Shepherd]

Nope, not the case at all. It'll happen to anything, bitmap or vector based.

[Chuck Stone]

Color fill is considered raster, correct?

[Dee Gallo]

I have written in my book: MacBook 100sp/35p/1000dpi. I collect settings even if I haven't tried them, so take it for what it's worth. Anyway, it has been shown previously that some banding can be caused by resizing an image after treating it in PhotoShop, but yours does not look like a photo. Is it a bitmap image? Others have changed a filled shape from 100% black to 80-90% black to eliminate banding. Please post your successful settings for future reference!

cheers, dee

[Avraham Monina]

Thanks Dee and Scott, I will post results.
But heres another question, if I try ti use 80-90% black, isent lowering the power or speeding up the speed will cause the same results?


I have written in my book: MacBook 100sp/35p/1000dpi. I collect settings even if I haven't tried them, so take it for what it's worth. Anyway, it has been shown previously that some banding can be caused by resizing an image after treating it in PhotoShop, but yours does not look like a photo. Is it a bitmap image? Others have changed a filled shape from 100% black to 80-90% black to eliminate banding. Please post your successful settings for future reference!

cheers, dee

[Scott Shepherd]

Thanks Dee and Scott, I will post results.
But heres another question, if I try ti use 80-90% black, isent lowering the power or speeding up the speed will cause the same results?

No, not at all. By changing the color to 90% black (which is not what I'd suggest in this case), it'll create dots further apart on your graphic. So the edges will be a little jagged, instead of pretty smooth. If you reduce the power or speed up the speed at 100% black, you still have full coverage of the dots. Two totally different things.

I can't speak for your machine but banding can be a bear to get rid of. Sometimes going very slow works, taking it out of focus some helps too. Maybe focus .030" above the work, run it at 40% speed (don't know what power to recommend for you). All these things can help.

[Avraham Monina]

I understand, thank you!

[Yuriy Karpov]

I've found that some coated materials have banding effect, sometimes it helps to lower the power for about 20-30%. It might be just uneven coating.

[Avraham Monina]

So, after much trial and error I finally got decent etching with very very minimal banding, Check out the first photo, I intentionally made it darker in photoshop so you can see the banding better, I tried different speed and power settings, then I changed the color from totally black to grayish and got better results BUT I started to notice that there are spaces between the dots (see 2nd photo), 2nd photo is a super close up (like 300%) but I can see the difference with the naked eye and I imagine that once you do etching that you dont have the other to compare to you would not notice the difference.
I used the RGB gray #666666 Power - 40 Speed - 100, autofocus ( I did try to lower the bed a bit but did not see a difference as banding was still very visible)
Thank you all for your help, I am open to other suggestions from anyone.

[Scott Shepherd]

I think 100 power is WAYYYYYYYY too much power. Try 40 speed, 15-20 power and work from there. 40 speed with 100 power is very hot, way more than you need for this, I think.

[Avraham Monina]

Scott, I might have wrote it wrong, but I used 100speed not power, I used 40 power


I think 100 power is WAYYYYYYYY too much power. Try 40 speed, 15-20 power and work from there. 40 speed with 100 power is very hot, way more than you need for this, I think.

[Kees Soeters]

Hi Avraham
Can you make the first picture so that you write your settings in each part so we have an overview where some setting lead to?
I also did some tests on glass and noticed quite a difference in powersettings and speed.. Every matarial will have his own settings however..
I also noticed that vertical banding has to do something with power.... could this be a instability in the HV-supply?? Can we tune the HV-supplies with a larger capacitor for instance? or take a supply that's intended for a tube with more power (60W tube with a 80w supply for instance)???
who??

Kees

[Avraham Monina]

240665

Im sorry I dont remember all of them, but I wrote down as much as I can.

Hi Avraham
Can you make the first picture so that you write your settings in each part so we have an overview where some setting lead to?
I also did some tests on glass and noticed quite a difference in powersettings and speed.. Every matarial will have his own settings however..
I also noticed that vertical banding has to do something with power.... could this be a instability in the HV-supply?? Can we tune the HV-supplies with a larger capacitor for instance? or take a supply that's intended for a tube with more power (60W tube with a 80w supply for instance)???
who??

Kees

[Scott Shepherd]

Just for giggles, try one at 30% speed and 20% power, 100% full black using a RGB palette (R=0,G=0,B=0).

[Kees Soeters]

Thanks Avraham, for your data.
Unfortunately i don't see any logic coherence.... till now...

Still don't know what is the essential cause of banding.. Apparently not something like Moiré...

Kees

[Scott Shepherd]

Kees, it was explained to me which lasers created banding. I can't explain it because it was over my head, but seemed to make sense at the time. It's something to do with the internal chamber where the beam is created. I was told that they had created one in their lab that did not have any banding, but the process to do so was so expensive that they couldn't bring it to market.

It's a physical problem with the way the beam is created, it has zero to do with the graphic, in this case.

We've owned 3 mainstream lasers and every one of them has experienced banding on some material. Each manufacturer seems to have different sweet spots for reducing it, so what works on one, doesn't always work on the other.

[Shawn Conklin]

you need to keep an eye on that, if your under warranty still you should work directly with epilog. we had the laser replaced on our Epilog 6 months in because the banding was heavy like yours. The replacement improved the banding substantially.

A little banding is normal with the solid blocks of engraving and the 80% black fill trick works great to stop it but I think yours is leaning on the heavy side, especially for cermark. I would be curious how dense the banding is if you do acrylic . Our replacement laser had almost no banding with cermark and only a little with acrylic. The 80% black cleared up the rest.

You can see plastic banding here. about half way down the black macbook lid. If they used 80% fill they probably wouldn't of had the issue.
http://www.ladyada.net/wiki/laserinfo/settings


We had tried everything under the sun including running purified power into the laser because we thought the main lines from the power company might have been cycling weird.