Help from experienced

[Giacomo Cheslaghi]

Hi everybody,

I'm working on a project using smooth plastic sheets, I engrave them, and then use some product rub 'n buff-a-like, since it's the only way I found to give them a scratch-proof color. (advices welcome :) )

my problem is:
when I have a high contrast beetween the plastic (example: black) and the paint (example: silver) I can see the dots left from the engraver, both at 500 and 1000dpi.

is there any technique/trick to avoid it? I heard something about running the job out of focus, I tried myself but didn't come out with something acceptable, after a few tries the mark became blurry...


any help is appreciated :D

[Mike Null]

It would be helpful to see a picture.

[Richard Rumancik]

Generally 500 dpi should be adequate resolution for most plastics. What made you decide to engrave at 1000 dpi? In some cases it may be warranted but it is probably not common to need such high resolution. Also, what lens are you using? FL 1.5" or 2"? If you are using 1.5 you could try 2". This will enlarge the beam diameter and possibly soften the look. Are you seeing individual dots or are you seeing horizontal raster "rows"?

[Mike Null]

Is this a bitmap image?

[Dan Hintz]

Two possibilities immediately come to mind (and Mike alluded to one). If it's a bitmap, make sure that white is truly white and not speckled with off-white pixels. Another possibility is the cartridge tickle is set too high and you're getting stray dots. It's more likely the first, though.

[Giacomo Cheslaghi]

I'm trying to get a clear picture but it must be really close to see the effect.

what I have here is a pattern effect (not lines), I decided to try to run the job at 1000dpi hoping to get rid of the problem.

I only work with illustrator so it's a vectorial image, two color white and black, no greys

Don't get me wrong the picture look great, but the large engraved areas show the thousands of dots that were engraved once it's colored.

Richard I'm not sure about the lens, I'm using the Zing machine as Epilog build it.

[Dan Hintz]

Post a pic, else we're just guessing... include the image you're trying to engrave.

It sounds like might be using a non-RGB color palette (e.g., CMYK)...

[Giacomo Cheslaghi]

I will ASAP, thanks Dan

[Richard Rumancik]

Maybe Dan is on to something - I took a quick peek at the Zing manual. You are using the "general" tab, not color mapping, correct?

It kind of sounds like it is dithering - but when you dither true RGB black (100%) nothing much happens as you aren't trying to simulate a "shading" effect. Here's a little test. Draw two squares in CorelDraw. Fill one with RGB Black and one with CMYK black. Then convert each to a bitmap using dithering. The RGB black will map 100% black. The CMYK will map perhaps 89% black. CMYK black converts as "gray" relative to RGB black.

I don't think you should need 1000 dpi. You are attempting to fix something but resolution is not the culprit. Something else is going on.

[Mike Null]

I think the issue is with your driver settings. It appears as if you may have halftone selected somewhere in the driver. I would go back and check all your options to be sure. Take a look at your manual to see if they tell you how to set up for this type engraving.

[Mike Null]

Have a look at this. It maight solve your problem. http://www.epiloglaser.com/tl_colormgmt_corelx5.htm

[Giacomo Cheslaghi]

last night I took some time to make some experiments.

what you said about the RGB instead of the CMYK is absolutely right, what I thought was deep 100% black was not, and I saw it perfectly as soon as I switched to RGB.

now the result of the engraving is much smoother,

thank you very much Richard, Mike and Dan for your help :)

[Dan Hintz]

We aim to please... glad it worked out for you.

[Richard Rumancik]

Giacomo - did you not get a palette from Epilog for the Zing? Just to make it easier I would have thought that they would have given you load a "Zing" palette into CorelDraw. The advantage to this is that it helps you avoid using "illegal" colors in your drawings and layouts. Of course, you can still get caught when you import stuff.

If you don't have a Zing palette I would suggest you make one. I think for color mapping your laser uses 6 colors? So you want a palette with those 6 plus black plus white. (I recommend adding the white as it can be used to blank out unwanted items when rastering.) You can create your own palette for use in Corel by selecting these basic colors and creating a palette name for it.

Then when you do import anything just make sure that you change any bad colors to "legal" ones or else it may map wrong or do the dithering thing.

[Giacomo Cheslaghi]

Richard I'll try to do that with Illustrator..

this is the texture I get now when I do 100% rgb black, do you guys think it's a good result?
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