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John Niemi
12-09-2008, 12:38 AM
Hi,

I thought this was going to be easy. I got my new laser engraver and am starting to learn to make signs. I made a Red on White Acrylic KEEP OUT sign. The problem is that after engraving the letters were pink and not white.

The setting used were the Acryic raster engraver settings which are 100% speed and 55% power. The laser engraver is an Epilog Mini 35watt

I had better luck with my yellow on black acrylic sign. The letters came out black.

Any help will be greatly appreciated.

John

andy blackett
12-09-2008, 2:26 AM
Hi John,

We've got the same machine, I asked Identify (the rowmark dealer here in the UK) why this happened with Red/White and apparantly its to do with the weight? of the red pigment, instead of being sucked up and away it sinks back down.

What we do to resolve this is to do two passes, the first being just raster, the second being raster and vector. Thereby rastering twice to clean the white up. This works a treat. Also try wiping the plastic with panel wipe or meths between passes to clean as much of the mess off as possible. (take great care not to move the piece or it'll mess up on the second pass)

Hope this helps

Andy

PS. We use 80% speed and 37% power, if you bump your cutting speed up a couple of percent you'll notice a difference in engraving quality and wont be pushing the machine to its limits 24/7

Mike Null
12-09-2008, 6:25 AM
You will quickly find that this problem is a characteristic of the plastic and not just Rowmark. It will happen to a lesser degree on other white color combinations.

You can mask the engraving with transfer paper (a lot of extra work) or after the engraving is done flood it with a cleaner diluted with water (such as citrus clnr). While you have it flooded gently brush out the red particles. They be in suspension rather than being smeared into the white.

If some remains a good eraser will remove it.

I use air assist only for cutting this material.

Kenneth Hertzog
12-09-2008, 7:42 AM
Welcome John

The panel tags that I make I found that I will make a couple of passes rather than trying to do it all in one. Found that I got better results that way. Cut your speed and power down and take your time it doesn't warp the plastic and gives you a better cut. Found that this method works on other colors as well, if you watch the cut you can tell when the red ( pink ) is gone.

Just what I have found out.

ken

Brian Robison
12-09-2008, 8:18 AM
Also use the bottom up engraving technique so that the lasered pigment isn't being drawn by the vacuum into the engraved area.

John Niemi
12-09-2008, 9:36 AM
Hey,

This is great. When I get home tonight, I am armed with new ideas.

Two engraving passes
Slower Speed and lower Power.
Clean carefully between passes.
Use the bottom up engraving technique

Thanks for all the help.

John

John Niemi
12-09-2008, 9:40 AM
You will quickly find that this problem is a characteristic of the plastic and not just Rowmark. It will happen to a lesser degree on other white color combinations.

You can mask the engraving with transfer paper (a lot of extra work) or after the engraving is done flood it with a cleaner diluted with water (such as citrus clnr). While you have it flooded gently brush out the red particles. They be in suspension rather than being smeared into the white.

If some remains a good eraser will remove it.

I use air assist only for cutting this material.
Mike,

I am not clear about your comment that you use air assist only for this material. Can you tell me more about this and why it helps?

Thanks,

John

Joe Pelonio
12-09-2008, 10:19 AM
Some liquids turn the red dust into paint and make it permanent. I found that cleaning with Sprayway glass cleaner (Costco) takes it off nicely. You will also find that a lower dpi such as 300 will result in cleaner results, since there are not as many of the tiny ridges to hold the dust.

Dave Johnson29
12-09-2008, 10:59 AM
Also use the bottom up engraving technique so that the lasered pigment isn't being drawn by the vacuum into the engraved area.


Hi Brian,

What is the bottom up technique?

I did a search and only got this post again. :)

Brian Robison
12-09-2008, 11:20 AM
The Epilog driver has an option to let you engrave starting at the bottom instead of the top. The vaccum pulls air toward the top so anything already engraved gets particles pulled over finished area. It helps out with plastics and wood.

Mike Null
12-09-2008, 5:41 PM
I believe air assist during the rastering operation just exacerbates the problem. I now just use air assist for cutting regardless of the material.

Using air assist during the cutting operation keeps the flame down.

John Niemi
12-10-2008, 12:34 AM
Well the results are in.

Good advice produced nice white letters and very little debris.

I incorporated all of settings suggested. Not a very scientific approach but one that yielded excellent results.

300dpi not 600 dpi
Two engraving passes
Slower Speed 80 and lower Power 37.
Air assist off for raster engraving
Used the bottom up engraving technique.

No cleaning required at all.


Thanks to all

John

Mike Null
12-10-2008, 5:54 AM
John

A couple of other points. On red/white in particular I sometimes brush on some mineral spirits before engraving. I think it helps but isn't one of the great discoveries.

The power thing is more important in many ways as too much power can reduce the sharpness of your image on laminates, wood and even anodized aluminum. So as you have time it's worth experimenting with power settings on all materials to see what produces the best results.