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Michael Simpson Virgina
10-10-2011, 4:44 AM
Using a raster I want to transfer some high contrast images. (mostly lines and text) to wood. Im getting a lot of engraving which I dont want. I want minimal engraving and maximum burning (marking) on the wood.

Whats the trick to this. Currently Im using popular.

Joe Kace
10-10-2011, 6:41 AM
Can you post a pic of what you are describing, sometimes this helps in determining what is going on and needs to be done to correct your problem.

Michael Simpson Virgina
10-10-2011, 7:05 AM
Its not nessarily a problem. In many of the posts on the forum people ask how to engrave or cut the wood without burning. I want the opposite. I want to burn the would with as little of engraving as possible. I think I may just need to move to a denser wood.

George M. Perzel
10-10-2011, 7:31 AM
Michael;
I am also confused-what do you mean when you say "as little of engraving as possible"??
Poplar is a poor choice for engraving-not very good contrast.
Best Regards,
George
Laserarts

David Fairfield
10-10-2011, 8:17 AM
I think that may have something to do with the species of wood you use, as my results vary from wood to wood. You can try going out of focus slightly. I haven't tried this, but possibly a clear varnish may darken with heat and enhance your marking.

Mike Null
10-10-2011, 9:24 AM
Certain woods, poplar being one, do not darken as well as others. I find that darkening is a simple matter of burn time or what I call dwell. To increase the burn time you can slow the speed, increase the dpi or both. One problem with this is that if you keep the power high your depth of the engraving may be more than desired.

You may find that a slow speed and lower power will achieve the result you're after. I am not a fan of defocusing but others seem to have some success with it.

Frank Corker
10-10-2011, 9:53 AM
This is a matter of interpretation as to what Mike is after as far as I can see. I think you might be referring to getting a darker mark without engraving deeply. If that is the case there is some stuff on the market which you can get on your side of the pond (the colonial part) called laserdark. It adds a darker marking to the inside of your engraving a little like 'fill' but without the paint. If you do a search on laserdark you should find it relatively quickly.

Some woods engrave better than others. I have some of that beautiful cherry wood which was kindly sent to me by George Perzel and Ray Mighells. It engraves and marks so well it brings a tear to your eyes and it enhances even more when a finish has been added to it. I also have some beech here which although a beautiful grained wood, the contrast is extremely disappointing, it engraves well....you just can't see it! Darker woods also engrave very well but images quite often have to be negatives in order to see them correctly but because they are so dark it has a disappointing result. Baltic birch and plywoods engrave well and because the wood is blonde it tends to show the contrast well also.

So if there is a trick, it's in the paragraphs I have put above, is this what you were meaning?

Ruben Salcedo
10-10-2011, 10:30 AM
Michael,

what you are looking is to have a burning effect without depth?, If so then just get it out of focus, you'll need a wood species that gives a high contrast burn.


Ruben

Glen Monaghan
10-10-2011, 12:35 PM
So you want a dark mark but without removing wood/cutting into the surface. I recently had a similar desire, albeit on a different substrate, while creating a "celebratory toast" and a unique birthday greeting chip. With those projects, I found that the general approach is to reduce power enough that the substrate is not vaporized or burned away, and reduce speed to allow the low power long enough to darken the substrate. It takes a bit of trial and error, alternately adjusting power and speed, to find the "sweet spot" where the surface darkens adequately but doesn't get heated to the point of burning or vaporizing (because that removes material/cuts into the substrate).

The problem is, you simply can't do this with some substrates. You need a substrate that will provide sufficient contrast without decomposing. I haven't tried poplar but I know some woods (such as the cherry I used for a funeral urn) provide good contrast, while others (such as oak I've used for grips) are highly variable according to their grain structure, and yet others simply don't produce much color without creating char, which erodes the surface.

So, long story short, try low power and low speed, and experiment with some different wood.

-Glen

Michael Simpson Virgina
10-10-2011, 12:40 PM
Thanks guys. You gave me some things to try. I have some cherry and maple to try. I will also try adding a finish as well to see how that effects the burn. I will also try reducing power and speed, and focus.

David Epperson
10-10-2011, 1:22 PM
Thanks guys. You gave me some things to try. I have some cherry and maple to try. I will also try adding a finish as well to see how that effects the burn. I will also try reducing power and speed, and focus.
I don't use lasers on wood, but we use them at work for marking very small text on plastic. From my experience it only takes being "out of focus" by being as little as 1/8" out of plane to start causing the effect you are after. But you will of course also lose some degree of "crispness" to the image with that method due to the out of focus condition also causing the beam spot to be larger. Reducing power and speed to 1/4 or 1/2 of normal and working from there should allow you to find that sweet spot without sacrificing the sharpness of the image.

Michael Simpson Virgina
10-11-2011, 12:50 PM
So far two coats of Shelac seems to give me the effect I want.

Trevor Watson
10-13-2011, 9:36 AM
Skuff Stuff brown or black is great ! :) you know the Shoe polish in squeezable bottle with the Foam applicator on the top .. dap it into the engraved area wipe off excess adds alot of contrast
brown or black to engraved items :)

Trev