Contents:
In this post, we will describe the method of engraving this material, what glass engraving machine to use, and how.
What instruments to use?
There are two ways to engrave glass: manual and automatic.
- Manual
Well, the manual is not fully manual, as it usually is: in one of the ways the micro motor rotary machine is being utilized. Also diamond drill bits.
In that case, obviously, the human factor is sky high, and we are not talking about fast production. This is an option for hand-made art or goods. In that case the master has a big control over the depth of cutting-in the material. And digitalization may be over the top.
There is a different variant. It’s called Stripple, also hand-made. But here the main instrument is called a scriber, and the process consists of repetitive pitter-patter (tapping) on glass until the appearance of little, almost microscopic dots or hollows. That’s a very laborious and prolonged type of the true manual work.
But it’s obvious that these two methods are not suitable for serial manufacturing. For that task machines are required.
- Automatic
Here we’ll talk about two variations again. First one is sandblasting.
An abrasive compound is being blown with the compressed air in the glass, provoking the cracks to come into sight. And those parts that don’t need to be processed are covered by the masking material. So, the required image is made on the surface.
This method is used quite frequently in the commercial scale, but you need to take into consideration that it’s required to constantly keep track of the homogeneity of used abrasive materials. And they may differ, and each type gives an unique effect to the glass.
Second variant — lasers, lightsabers, Death Star.. I mean, a glass engraving machine. In that case the whole work is provided by the CO2 laser beam by virtue of evaporation of materials. In that case you need to watch closely for power and speed. In comparison with sandblasting this way of engraving is easier due to:
- laser glass engraving machine is more compact than a sandblasting one;
- no need in tracing the abrasive condition and picking the type of it;
- a pasting on of the masking material is a quite time-consuming, especially if your layout is intricate;
- the sandblasting equipment in majority can operate only flat surfaces, when the cylindrical shapes might present a problem.
So, let’s talk about the glass laser engraving and go through the details.
What glass to use
It appears to be that a chipper one is more suitable for laser glass engraving since it has less plumbum in it. Thanks to that the material has more homogeneous structure.
Other types, like crystal glass or expensive blown, can easily crack. That happens because of the thermal loads.
On a CO2 laser machine you can operate the window glass, mirrors, and dishes like… glasses for different types of drinks.
Also there is a way to engrave mirrors by erasing the reflecting layer on their backside, without touching the glass itself. That’s something the fiber lasers can do.
Which glass engraving machine to use
As we sorted out in some of our other articles, like this one about wood engraving, in that business you shouldn’t chase the most powerful superpower.
Let’s recap! The higher this parameter is, the brighter and bigger the laser dot happens to be. And the glass has one wonderful ability like reflection. In that matter, the smaller the dot is, the better.
That’s why any glass engraving machine with a tube up to 120W will be suitable.
The main part in the process is played by the minimum percentage. It’s amount is about 10% for any CO2 equipment. So, the lowest power from the 120W is 12W, from 160W — 16W, and further on. In conclusion, the percentage of power from the 60W tube is going to be 6, which is appropriate for the glass.
Wattsan has small tabletop models for hobby and a little production, like 6040, and bigger ones for big manufacturing, like 1290.
The process of glass laser engraving
Well, we covered the subject of materials and equipment. Now we should talk about the engraving itself!
- Image preparation
First thing first, you need to decide on the type of your picture: raster or vector.
- Raster engraving
To do so you have to start with transforming the image into the bit format. How to do that? We’ll show it in Photoshop.
- First. If the picture is variegated , you have to transfer it in the gray gradation mode. In bit format the amount of shades is limited, and is limited by black and white, so for everything to go smooth, the image better be discolored.
- Second. Find “Image” > “Mode” > “Bitmap”;
- Third. Find option “Output” and white down the resolution. Most of the time it’s the same as the original image.
- Forth. In the pop-up menu choose the appropriate transformation (for example, “50% Threshold” will result in the bright and high-contrast black and white image).
That’s all. You’re wonderful!
- Vector image
With that type everything is much simpler, because the vector pictures are usually already black-and-white. So you just have to prepare it for the engraving.
To the point of the preparation.
For the beginning you have to create the working area in the graphical program and make it with a 300 dpi. Next, import our image there. Check again that the picture is black and white, correct some moments and delete white edges if there are some. And then we export the image in the BMP format.
Open the file once more to ensure the result. And load the layout in the machine’s control program.
- Engraving without joints
We should separately talk about this type of engraving. It’s used for cylindrical objects. Glass engraving quite often is needed for decorating… glasses for different occasions, like weddings or anniversaries.
- Let’s figure out the circumference of the working piece. Here is where our school knowledge says, “Hello”. The length of circumference is 2πr. Π is roughly equal to 3.14. With the help of the calipers we do the measurements, multiply and receive the end number.
- Open Adobe Illustrator (or any other program of that kind). There we have to create a new file with the following sizes: width is the length of the working piece; length is the length of circumference we counted up.
- Create a frame with the same parameters.
- Make a pattern.
If the working piece has different diameter on top and bottom parts, then in the RDWorks you would need to set the bigger one. And during the file preparation you would need to additionally recount everything for the smaller one.
More difficulties will appear while working with the sphere: you would need a special system that tracks down the non metallic materials or the long focused lens.
Rotary device
That thing is required for those who decide to work with wine glasses, etc. Now, we’ll tell you how to connect it to the glass engraving machine.
- Make sure that the motors of a laser machine and rotary device match: three-step motors should be on both devices. And check sizes of the rotary device itself.
- Connect it to the laser machine instead of the axis Y.
- Turn on the equipment and open up RDWorks. In the “User” find a function Read and click it. In that case the glass engraving machine will understand that we connected the rotary device and will see it.
- Find the “rotation” option and click “yes”.
That’s it! Wait, no… now we have to set the circle pulse. We explained how to do that with all of the details in one of our videos, watch it, if you didn’t!
What to cover the glass with
The case is that we can engrave the glass by laser right the way it is, but for achieving different or more qualitative results we may try to cover the material under something: soap solution, wet napkin or paper towel, masking tape, etc. Let’s look closely.
- Soap solution. Best variant for very thin and, if I may say, delicate engraving. It’s great if lines in your layout are displaced very closely one to another. Also soap is easy to clean up after the processing.
- Wet paper towel. In that case, the engraving will be whiter and less shaggy. And it’s also simple to tidy up after.
- Masking tape. The image will be grayish.
- Blue tape. It’s preferable not to use it: the results are good, but the machine gets dirty, and the entire procedure seems filthy.
- On a dry basis. Here, you should lower the brightness of the black parts of the image from 100% to 70%, so the thermal impact would be smaller. And after, if you don’t like the roughness, you may get rid of it with the help of a scuff pad and water.
Settings
A lot of things rely on the power of the laser tube: set the percentage to 30, 65, or 80. It’s also tied to the material you’re using as a masking one. So we’ll present a few examples, but don’t be scared to experiment to get the greatest results! After all, isn’t this exciting?
The speed should be high, around 80%. However, like with any engraving. The usual dpi is set at 300. This results in the big-dotted picture. If you set the dpi to 400, the outcome will be like a morning frost on the window.
Conclusion
- There are two ways to engrave glass: manual and automatic. First one is an option for hand-made art or goods. That method is not suitable for serial manufacturing. For that task machines are required. There are two variations of the automatic processing.
- First one is sandblasting. This method is used quite frequently, but you need to take into consideration that it’s required to constantly keep track of the homogeneity of used abrasive materials. And they may differ, and each type gives an unique effect to the glass.
- Glass engraving machine is the second one, and in that case you need to watch closely for power and speed of the laser. In comparison with sandblasting this way of engraving is easier since a laser glass engraving machine is more compact, needs no tracing of the abrasive, and can operate both cylindrical and flat objects, unlike sandblasting machines.
- A chipper glass is more suitable for laser glass engraving since it has less plumbum in it. Thanks to that the material has more homogeneous structure. Other types, like crystal glass or expensive blown, can easily crack. That happens because of the thermal loads.
- You shouldn’t chase the most powerful laser tube. The higher this parameter is, the brighter and bigger the laser dot happens to be. And the glass has an ability to reflect. In that matter, the smaller the dot is, the better. That’s why any glass engraving machine with a tube up to 120W will be suitable.
- Before engraving you should prepare the image: make it black and white, raster or vector. Also you have to connect the rotary device to the glass engraving machine if you plan to use one.
- We can engrave the glass by laser right the way it is, but for achieving different or more qualitative results we can cover the material under soap solution, wet napkin or paper towel, masking tape, etc.
- Don’t be afraid to experiment with the working pieces! But there are a few helping points. The speed should be high, around 80%. The usual dpi is set at 300. This results in the big-dotted picture. If you set the dpi to 400, the outcome will be like a morning frost on the window.
