banding issue again!

[Linda Kroeker]

Hello everyone,

Read quite a few posts about banding...still not sure what the problem is from.
Was told from a Epilog rep it could be dirty bands or it could be the tube which would run
$2000 ouch! I have the banding issue on an off. Read that it could be dirty bearings, drive bands or graphic.
I used a square black box to test and send to the rep...ran it before cleaning and after...still has a slight banding after cleaning.

Any new advice on this same issue would be greatly appreciated.
Linda

[paul mott]

Hi Linda,

Everybody has an opinion on this one but nobody really knows the answer, perhaps because there is more than one possible cause. Even the machine manufacturers / suppliers differ in their opinions. So far all the suppliers I have had contact with say that their machines do not suffer from this problem but their rivals machines do have the problem.

I still get this on occasion and I have been told that it is mathematical in nature and related to pixel / dpi etc. but I am still convinced that, in my case, it is uncontrollable variation in tube output power / psu output current. I have tried exactly matching the pixel count with the steps and image size but without 100% success. One day I will get to the bottom of this.

Paul.

[Mike Null]

That you made so much improvement with the cleaning would lead me further on that path. Perhaps another cleaning, checking belts and pulleys, mirrors and lens etc.

[Rodne Gold]

Almost all our banding problems were cured by using a 2kva battery filled UPS which smoothes the mains voltage.
I would also try to lube all bearings and the motion system and try to fix the object you engraving more securely as it could be moving slightly cos of air assist, temp expansion of the object, vibration of the machine itself.
An easy way to check if the banding has to do with something mathematical is to rotate the pic 45 degrees and engrave it , if the banding is still horizontal and not 45 degrees stripes or has dissapeared , its mechanical or power related.
You can also try introducing some noise in the photos you engrave to "randomise" pixel distribution.
Often noise smooths things. For EG a blue sky with a few red clumps will make the red clumps stand out , introduce more red clumps and distribute em evenly in the blue sky (add noise) and the sky will appear a slight more purply but you wont see the few clumps.
Reducing engraving speed often also works well, you can try some other DPI figures too - the "native" dpi of your laser might not be a multiple of 300 or 600 or 1200 , it might be something else , try 250 380 500 etc

[Linda Kroeker]

Thank you all...I was told by my rep this morning that it still sounds like the tube...but try to do more cleaning, which I will do today and run a new sample.
I told them about this issue a few years ago, but then was told it was a graphic issue...tube was still under warrenty then...hmmm.
For now I will just keep the focus out, since it's not as noticable.

you guys are great!
Linda

[paul mott]

Linda,

Just a thought but if you do go for a new tube make sure you get everything concerning the banding in writing first just in case the rep is wrong and the problem still persists after you have parted with your $$$. ;)

Paul.

(I really don't think it is the tube).

[Linda Kroeker]

still slight banding after more cleaning...larger left box 600dpi 100s 70p
smaller rt box 400dpi 90s 80p...I guess best thing for now is to go slower and lower dpi...until??? can't afford a tube...

184631

[Mike Null]

If your machine is working well in other functions I doubt you need a new tube.

[Joseph Belangia]

I get this from time to time. In most cases, it's because I didn't run face fix in PhotoShop - which does a bit of pixel diffusion.

You can see it here a bit...
http://farm6.static.flickr.com/5219/5488308883_235ba351ce_z.jpg