View Full Version : Need Tips. Rowmark Reverse Engraving Material

Shawn Handley
06-03-2010, 12:06 PM

I have a custom yacht electrical panel to make. The owner has chosen the material he wants to use. It's Rowmark Reverse Laser Mark (shown here on page 7, Ivory) (http://www.canadianengravers.com/supplies/Rowmark%20Laserable%20Materials.pdf). We have a Epilog Legend 36EXT 50W.

We use Rowmark Reverse Laser Mark for most of our little projects but this is the first time I am making something this big (a couple inches shorter than the entire 36 x 24 table).

I am looking for tips. What to do, what not to do. That sort of thing. I know, it's a pretty general request but I will take anything you can give. :)

A few notes on the panel:

1. This is going on top of a metal sheet. It needs to be exactly the same size.

2. Hole MUST line up on the metal sheet and the plastic. The metal will be cut out by a waterjet (always perfect).

3. I don't like the colour. LOL But seriously folks, it will be backfilled with blacks and blues as well as a translucent blue for light to shine through.

I have it all drawn up, I just need to push play. There is no major rush so I am going to try to develop some more knowledge with your tips. The whole reason we bought a bigger laser was so we could do larger projects. I will be taking this knowledge a looonnnnng way.

Mike Null
06-03-2010, 12:37 PM
When I have done these using the customer's drawing I have found that the measurements are slighty off. That may be because of importing CAD into Corel but anyway I've had to check and double check to achieve precision. Include that in your set up charge.

If possible you can mask first then make a test run for alignment on the mask.

Rodne Gold
06-03-2010, 1:16 PM
Another issue with that material is that large areas of engraving tends to warp the material a bit , you need lots of air assist to cool it down.

Richard Rumancik
06-03-2010, 3:23 PM
I am looking for tips. What to do, what not to do.

I suggest you cut out a mock-up out of poster paper, clear mylar, corrigated cardboard, or whatever you have on hand, so you can do a test-fit of the mechanical aspect. You may find that your laser is "off" in one direction or another, and may need to compensate. (I do this all the time on large parts.)

2. Hole MUST line up on the metal sheet and the plastic. The metal will be cut out by a waterjet (always perfect).

Well, nothing is really "perfect" . . .there are tolerances on every process. The best you can aim for is the nominal dimension. The tolerances on each part should be accomodated by the design . . .

However, if they lend you the metal part you can tweak to match if you want to, but it will be time-consuming.

Another suggestion: make sure the sheet is well-secured from moving.

greg lindsey
06-03-2010, 5:18 PM
OK, I do several of these a month, they are all water jet and I swear no two are exactly the same. I use a 1/8" clear acrylic pc and cut it to thier drawing then engrave it. I use it as an overlay, so I can tweek it as necessary. BTW, I do charge them for the entire process and they are most happy to pay to get it correct. These are Helicopter/ aircraft panels.

Niklas Bjornestal
06-04-2010, 8:14 AM
Wouldnt it be easier to let them cut the acrylic with the waterjet and then let you engrave it for them, then it should be a perfect match.

Dan Hintz
06-04-2010, 8:47 AM
Then the engraved text may not match up with the holes.

Shawn Handley
06-04-2010, 6:06 PM
Ok, I did a small mock panel today. I am having a problem with a second pass. In parts of the panel, it will 'frost' the plastic. In others, it will become crystal clear. I will try and get some photos but any idea why it might do this?

Dan Hintz
06-04-2010, 6:12 PM
Is the panel completely flat? If not, your out-of-focus areas may end up more clear than those in focus.

Shawn Handley
06-04-2010, 6:14 PM

I thought the panel was flat. I will have to try again on monday.

Dan Hintz
06-04-2010, 7:28 PM
Not a focus issue... the delineation is too sharp. Was there a covering on either side of the plastic?

Very odd that the sides are nearly exact opposites of each other in terms of clarity/milkiness...

Shawn Handley
06-04-2010, 7:31 PM
It is odd, isn't it?

No covers on either side.

I forgot to mention that the near-bottom part of the pic where the obvious stop is is where I stopped the engraving on the 2nd pass. Everything below that line is just the first pass but it's not enough clarity to pass as professional.

The pic is also upside down. LOL

I did top to bottom with the first pass and bottom to up with the 2nd.

Dan Hintz
06-04-2010, 9:25 PM
I did top to bottom with the first pass and bottom to up with the 2nd.
That's a potentially useful piece of info, particularly when the frosting is anti-symmetric...

Scott Shepherd
06-05-2010, 8:37 AM
How big a part are we looking at? If it's large, then I would say it's a bowed piece of plastic. One side is sitting up 1/8" higher than the other side, that's why one side is clear, one frosted. However, if it's a small piece, you wouldn't see that much different in bow over a small area.

I engrave a lot of reverse engraving material and it's a struggle. What works this week, won't work next month. I've had it super clear, so clear you can see your fingerprints through it, then run the exact same settings 2 weeks from now and it looks horrible. It's a difficult material to deal with, especially when they are shipping bowed material to us.

Shawn Handley
06-05-2010, 10:25 AM
We're probably looking at about 3 or 4 inches tall.

I taped everything down inside the machine so it would resist the bowing. It felt flat and not bowed.

If I turn up the power (or slow it down) I get a clearer shine-through but the front starts to warp where the engraving it. There doesn't seem to be a happy medium for this stuff.

Scott Shepherd
06-05-2010, 11:53 AM
Is one side against the very far edge of the travel, i.e. "X=0" area?

If so, it might be the ramping down to stop and change direction. If it's against the edge, try moving it over 1" and see if that solves it. If you're not against the edge, then I don't have an answer right now.

Shawn Handley
06-05-2010, 12:44 PM
It's exactly 1" away from the edges

Scott Shepherd
06-05-2010, 1:09 PM
That's a tough one to figure out, not being there. On many reverse engraving projects, I have to engrave them twice, at lower power to get through good and clean. Many materials, especially the darker ones will leave traces of that color and it looks decent laying in the laser, but when you take it out or paint fill it, you see the slight haze of the original color. So instead of trying to cook through it in one hot pass, maybe back off and try 2 passes, less power.

Just a thought to try and get you through this one, but long term needs a better solution.

I just fought a reverse engraving project that had a large area removed. After hours and hours trying to make it work, the light bulb came on, I cut a paint mask, masked it from the backside and painted it, removed the stencil and it was done, all in 15 minutes. Spent hours and hours trying to make it work on the laser.

Doug Griffith
06-05-2010, 1:29 PM
Not a focus issue... the delineation is too sharp. Was there a covering on either side of the plastic?

Very odd that the sides are nearly exact opposites of each other in terms of clarity/milkiness...

That is interesting. If it appears on the second pass, could it be that there is conflict in dithering similar to moire?

Doug Griffith
06-05-2010, 1:34 PM
That is interesting. If it appears on the second pass, could it be that there is conflict in dithering similar to moire?

If it is "moire", try running the second pass at a different DPI.

Rodne Gold
06-05-2010, 4:11 PM
Are you running air assist - try different pressures if you are - try lower pressures first. AFAIK the Rowmark laserable reverse (you are using the laserable type?) has an acrylic base which would be sensitive to over cooling and perhaps melt issues.

Shawn Handley
06-07-2010, 10:34 AM
I wish it was moire. I would just set it out of focus to enlarge the dpi.

Yes, I am using the laserable stuff; however, when I use air assist, it appears the engraved dust ends up in the rough engraved area and proves very difficult to get out. Back filling becomes very tough. The only cleaner I can find that wont cause cracking in the plastics is a 3M orange smalling expensive can of cleaner/degrease but it seems to be oil based and I cannot paint over it without major fish eyes. Of course, alcohol will cause cracking.

I will try engraving again with air assist and see what happens. I do not usually engrave raster images with air assist.

Thanks again. I'm about to try again and I will report what happens.

Scott Shepherd
06-07-2010, 11:18 AM
I've never had any luck rastering with air assist on either. Can you try moving the entire thing over another inch or two to the right and see if that helps? I still think it's a ramping down of speed issue. Are you at 100% speed? If so, try moving it if you can.

Shawn Handley
06-07-2010, 11:21 AM
As it goes, the air assist wont turn on for raster for me anymore. I changed the settings in the config menu with no luck. Oh well. I have it moved over 2 inches this time. Last time was just one inch. I am running 70% Speed right now.

EDIT: Air assist was on but it didn't sound like it. The air assist made a mess with the dust into other engraved areas.

Shawn Handley
06-07-2010, 2:10 PM
Here's something interesting.

I am engraving 3 lines of text across a 20" area, Left, Middle and Right. As the optics (Y axis) runs past the Left and Right texts, that's when I get the cloudiness. The Middle line of text is clear as day.

I assume this has something to do with the fact that the Left and Right texts get fired upon twice in a short amount of time. Do you think this would have something to do with the issue at hand?

Here's a photo, cropped to fit the 20" across into just a few. You can see the vector grid underneath the middle text but not left or right:


Dan Hintz
06-07-2010, 2:30 PM
If it's a heat issue, you should be able to recreate it on any line by slowly increasing the power... if it is the heat, eventually even your clear line will begin to look fuzzy.

the easiest way to test it, though, would probably be to run just the text in the middle... with the carriage going back and forth over just that spot, if it turns cloudy, I'd say it's a good bet you found the cause. If it stay clear in the middle of the table, I'd lean more towards focus and/or beam alignment.

Shawn Handley
06-07-2010, 2:32 PM
Thank you for the reply.

When you say "it's a good bet you found the cause," are you talking about too much heat?

Scott Shepherd
06-07-2010, 2:37 PM
I'm not sure I understand your description, but if I do understand it, then you can put vertical lines about .030" thick that run down the left and right of your graphic, outside of the graphic. So you're just putting a line down the left side and right side, outside your image.

Then it makes the motion stay the same all the way down.

That's Epilog's fix from the factory, or at least it was when I had that problem.

So it would look kinda like this :