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Introduction to Laser Engraving

by the legendary Marc Stipo

Introduction

 

Laser Engraving. What is it exactly. According to Wikipedia:

Laser engraving, which is a subset of laser marking, is the practice of using lasers to engrave an object. Laser marking, on the other hand, is a broader category of methods to leave marks on an object, which also includes color change due to chemical/molecular alteration, charring, foaming, melting, ablation, and more. The technique does not involve the use of inks, nor does it involve tool bits which contact the engraving surface and wear out, giving it an advantage over alternative engraving or marking technologies where inks or bit heads have to be replaced regularly.”

Well that’s about the most boring definition I have ever heard. To me, laser engraving is 21st century expressionism. It’s an artist’s tool. Just like a pencil, paintbrush, charcoal, what have you, it’s a really neat way of getting your artistic expression on a blank canvas. Where a common painters canvas is, well, canvas, a laser engraving canvas can be just about anything. Instead of building up on that canvas with paint, we use light and heat to burn away the canvas. By using different speed and power and even focus, we manipulate a canvas to burn hotter or lighter creating varied effects. The possibilities are endless. How cool is that? There is one down side though. Variables. Where variables are sometimes a good thing, too many of them can sometimes be daunting and overwhelming. And with a laser, there are almost infinite. For example, lets take speed and power alone. If your laser is adjustable in mm/sec and you can go from 100 to 600 in 1mm increments. And you take power, from 1% to 100% in 1% increments. Well, without going into probability theory and computations and here’s how you figure it. You take 500 (increments in speed) and 100 (percent in power) and that gives you 50,000 different speed and power combinations alone! (I think. It could be more but its 6:20 am and I haven’t slept much) If there are any math whizzes out there that can clarify, please do so. The point is not the number itself, but the vast size of the number. And that’s just two variables!  Now take into account substrate, color, shade, hue, saturation, just to name a few, and it’s a wonder why anyone would want to do this.

For me, it’s one simple phrase. Its when someone looks at my artwork and looks at me and goes, how the hell did you do this, and I see the pure wonderment in their faces. That’s what does it for me. I guess its how a magician feels after pulling off a spectacular trick.

So how do you get there? Where do you start? Knowledge my friends……….knowledge. I’ve scoured the internet for tips, tricks, techniques you name it. And don’t even get me started on scrap. You see, for the most part, with a laser it’s one and done. You can’t “unburn” something. Once it’s there, it’s there. Oh sure, sometimes you can go over it again, but how do you do it without ruining it. It isn’t easy.

I once took a 1.5 inch piece of pine that a client wanted me to burn a picture on using a cell phone picture, of a landscape scene. Now let me tell you, 1 Pine, 2 Cell Phone Picture and 3, Landscape are hands down THE WORST scenario you can come up against. So what did I do?  I bought a planar, and every time I engraved it and it came out like crapola, id plane it down and start over. This was a big piece of pine, with natural edges. When it was all said and done, I wound up with a ¾ thick piece, and a lot of kindling from shavings. Scrap happens. The key is try to minimize it.

By learning some basics about how a laser works, what substrates work, and HOW they work, and artwork techniques, (such as photo manipulation), by taking these courses, you will be well on your way to developing your own processes, and your own techniques. So let’s get started.

Laser Engraving In A Nutshell

 

How a laser works:

I’ll be taking a lot of the clinical definitions from Wikipedia and then simplifying them:

“A laser engraving machine can be thought of as three main parts: a laser, a controller, and a surface. The laser is like a pencil – the beam emitted from it allows the controller to trace patterns onto the surface. The controller direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is picked to match what the laser can act on.”

Think of it as being a kid with a magnifying glass, burning things using sunlight, only this is really precise

Here are some general terms you will need to become familiar with:

Raster Engrave: Raster engraving traces the laser across the surface in a back-and-forth slowly advancing linear pattern that will remind one of the printhead on an inkjet or similar printer.

Vector Engraving: Vector engraving follows the line and curve of the pattern to be engraved, much like a pen-based plotter draws by constructing line segments from a description of the outlines of a pattern.

Vector Engraving Cuts, Raster Fills, its that simple

Power: The amount of power that is send to the lens

Speed: The speed at which the laser head moves, therefore limiting the amount of time a laser is in the work at once

A vector setting is like using a really precise scroll saw. You just set your lineweight to something small, and the laser will cut along that line.

Types Of Lasers

 

Lets talk about the two main types of Lasers: CO2 and Fiber Optic

https://en.wikipedia.org/wiki/Carbon_dioxide_laser

The carbon dioxide laser (CO2 laser) was one of the earliest gas lasers to be developed. It was invented by Kumar Patel of Bell Labs in 1964,[1] and is still one of the most useful. Carbon dioxide lasers are the highest-power continuous wave lasers that are currently available. They are also quite efficient: the ratio of output power to pump power can be as large as 20%. The CO2 laser produces a beam of infrared light with the principal wavelength bands centering on 9.4 and 10.6 micrometers (μm).

What does this mean? Basically it’s the most popular laser on the market today, and readily available for a smaller price tag. It can engrave and cut a variety of substrates including but not limited to wood, plastic, paper, glass, granite, and leather. It cannot, however, engrave most bare metals, because the frequency of the laser is such that the beam bounces off the metal like bullets off Superman’s Chest. There are coatings and such that we will get into in a different course

fiber laser or fiber laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbiumytterbiumneodymiumdysprosiumpraseodymiumthulium and holmium. They are related to doped fiber amplifiers, which provide light amplification without lasing. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing can also provide gain and thus serve as gain media for a fiber laser.

Fiber Lasers are used more for marking. Barcodes, Lot numbers, etc, they are used mainly in commercial applications. It does extremely well on metal marking. The one thing about Fiber Lasers. Don’t ever look directly at the beam unless you are looking through Protective Lenses or special glass. It will burn your retinas out.

So I Bought This Laser Engraver…

 

I bought my laser after I saw it being demonstrated at a Trade Show. I saw all the cool things it could do, and it blew my mind. I originally wanted to sell glasses online through etsy. So what did I do? I bought this huge top of the line laser engraver from epilog. Its an M2 Fusion and its wicked cool. So what was my business plan? (Um, what’s a business plan) I just wanted to engrave glasses and sell them. Guess what, there’s a lot more to it. A LOT MORE. For the moment let’s focus on CO2 Lasers and what they can do.

Different Mediums

Here we will look at some common substrates:

Wood

 

Wood is by far my favorite substrate to work with because there are so many kinds. I especially like, you guessed it, photographs. By photographs, I don’t mean an interpretation, I mean a photograph. So I spent years and tons of money on materials and documenting things like a mad scientist. You see, wood is a funny thing. First of all stick with the hardwoods. Stuff like Maple, Birch, Cherry, Alder,  and Walnut. Walnut is the best for text and vector art. It doesn’t overburn and gives a nice rich deep crisp engrave. Birch is the best for photographs. Solid birch. You can do plywood but that is usually the bottom of the barrel birch.  If you get a solid piece with a nice smooth grain, it will come out beautiful.

Here are some tips when engraving with wood:

  • Always sand it first. Your engrave will come out much nicer
  • When done, wipe it down with water or sand it with 600 grit paper. “Overburn” or edge scorching leaves charred marks around your image. If you sand it lightly, you will get rid of that but still keep the crispness of your image
  • “Sneak up on it” It’s a term I use when you burn something multiple times fast with low power. It brings out the image a little bit at a time. You can always burn it again, you can’t unburn it. Also if you can sand it in between burning, that will help you as well, as long as your laser repeats
  • Stay away from Pine. What does pine have more than anything? SAP. When you engrave pine with even a little power, it boils the sap, and boy, is that stuff sticky. Plus one other caution about Pine. It catches fire really easy
  • Inlay: A Laser is really good for doing inlay work. You can cut and inlay mother of pearl, abalone, wood veneer and even paper! That’s a course for a different time.

Plastic

 

Plastic melts. That’s is all a laser is doing to plastic. Melting it very precisely. So Tip#1: Don’t use too much heat in one place for a very long period of time. It will essentially turn to goo.

The best plastic to engrave on is acrylic. NOT POLYCARBONATE. They are NOT the same.  Oh and if you are trying to get a nice frosty look on acrylic, use CAST acrylic, not extruded. You will know if you are using extruded because it will engrave clear.  And if you REALLY want it to look cool, buy NOVUS polish 1, 2 and 3 and polish it first. It will look like glass. Engraving acrylic, especially photos on acrylic, it tricky at first. But once you get used to what to look for, it comes out great. Then, on clear acrylic, you can light it up using flexible light strips. Again, that’s another class for another time.

Another thing about acrylic. It can’t hold a really high resolution. In acrylic you want to go fast with low power, and around 300 dpi in your image. With acrylic, you can get really cool effects also when you cut it using a vector setting. It almost polishes the edge.

Glass

 

Glass, actually, doesn’t engrave. It microshatters. That’s right. It explodes, at a molecular level. Nonetheless, it is violent. What is glass made out of? Sand…….mostly. However, there are air and water molecules trapped within the glass. When the laser hits the air and water molecules, the molecules rapidly expand, causing them to break apart the bonds that hold the silicate together. Do this a couple of million times and you get a rough surface.

Engraving anything on glass takes patience. Engraving PHOTOGRAPHS on glass takes the patience of Mother Teresa, Gandhi, and Buddha put together. Its cool when it works, however it takes LOTS of practice.

Marble & Granite

 

Granite and Marble don’t really engrave either. What the laser is doing is removing the polish of the crystals therefore creating a matte finish. Pictures do well on granite and marble. I will do a course on these two substrates as well in the future. The photo prep is not bad, you just have to get some experience at it.

Coated Metals

 

Coated metals such as anodized aluminum can be tricky as well because there isn’t really any shading. Its either exposed the underlying material, or it hasn’t. What gives it the illusion of shading is how much of the coating you have removed, and how much of the underlying material you have removed. It’s an interesting medium to work with, and with the addition of other colors, you can get pretty creative.

 

Conclusion

 

This course was created to give you just a taste of what you can do with a laser engraver. In classes yet to come, I will have not only lectures, but hands on assignments of what to do and how to do it. I am going to have guest lecturers, live feeds, seminars, you name it. Thank you for enrolling in this class, and I look forward to teaching you.

 

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