Laser Cutter

First introduction

The laser cutter is one of the main tools present in makerspaces. A wide variety of material is supported, from wood to acrylic, or leather and some can even work with metals to cite a few. All those materials in addition to its precision and speed allow for the creative mind of a maker to flourish with infinite ideas and be able to iterate and produce them in a short period of time.
That speed also allows it to iterate quickly in designs when prototyping while not giving up any precision and quality you’d want for a final piece.
It’s an indispensable tool for a makerspace.

Practical relevance

– This is what you will need the knowledge and skills for

After reading this module, you’ll understand how a laser cutter works and how to turn a computer design into a finished piece.

Overview of learning objectives and competences

In this module, you’ll learn how to set up the machine by starting it, placing your material and calibrating the laser. You’ll learn how to set up a file to send it to the machine’s software, then how to setup that software and how to start a job. Then you’ll also learn how to post process the finished pieces. You’ll also learn how to work safely around this kind of machine and be able to maintain the machine.

Required skills for this module

Basic computer skills and 2D conception skills learnt in module 4: 2D Conception (CAD)

Introduction

In this part you’ll learn what a laser cutter is, what it is used for, the different types of laser cutter and how they work. Here is what “Laser cutting” really is.

Laser cutting is a subtractive manufacturing process that uses a laser to engrave or cut different types of material.

How does it work?

A laser is generated, usually on the back of the machine, then redirected by a set of mirrors into a lens to focus it on the material. The laser is strong enough to vaporise the material by pulsating at high frequency. The head containing the lens is able to move on two axes which are controlled from a computer-generated design.
The way the laser is generated can vary, this difference can also change which material you can work with. Here’s the two main laser technologies that are used in laser cutting machines :

CO₂ Lasers; this laser technology uses a tube filled with a carbon dioxide gas mixture, by agitating the mix with electricity, this one produces a very strong laser with a wavelength of 10.6 micrometres. This wavelength allows them to work on a lot of materials like wood, acrylic, paper, textile, leather and some plastic. But not on metals. A more exhaustive list of usable materials can be found in the second module of this learning material: Craft and materials.

Fibre Lasers; this laser technology amplifies an incoming laser inside fibreglass. This amplification is done by getting energy via pump diodes. The laser produced with this technology has a wavelength of only 1.064 micrometres. This smaller wavelength allows the laser to have a much greater intensity from the same emitted average power. Because of this, they’re often used when working with metals.

Talking about the emitted power, this one can also vary depending on the machines. That power is measured in WATT (W). The more powerful the laser is in watt, the thicker the material it can handle or the faster it can finish a job.

Graphic from https://www.troteclaser.com/ showing the difference in time it would take to cut the same rectangle in different thickness of acrylic at 2 different power

Let’s now talk about what you can do with a laser cutter. Because of the great number of materials it can be used on, the applications are also very varied. From medical devices to jewellery, from industrial use in a production chain to a one man “do it yourself”, or “DIY” project.

Pictures from https://www.thingiverse.com/mutsuki/, https://www.domesticsluttery.com/ https://www.etsy.com/dk-en/listing/254138520/ https://www.deviantart.com/mtomsky https://www.protohaven.org/proto-shield/ http://maxoutput.co.za/services/

Security Measures

Picture by Lévi PONSARD

In this part you’ll learn how to engage with a laser cutter in a safe manner. Before actually using any laser cutter, some security measures need to be followed. These devices can be dangerous when handled by untrained personnel. The machine itself will have built-in security measures; most devices won’t start a job if the lid isn’t fully closed. Additionally, most laser cutters will also be equipped with an emergency stop button.

These should only be used in case of emergency, stopping and pausing a job can often be accomplished by other means. Always refer to your machine’s manual.

The room where the laser cutter is located should be secured in case of fire. No flammable materials should be near the machine, good fire doors and ventilation should be provided in case of gas leakage during cutting.

In addition to this, the room should be equipped with a dry powder or a CO2 fire extinguisher in case the device takes on fire. Do not use a water or foam based fire extinguisher as those do not work on electrical devices. A first aid kit and a fire blanket in case of injuries should also be available nearby.

Important
Never run the machine unattended!

Setting up the machine

In this part you’ll learn how to start and setup the machine and place the material to later on create your designs. Here’s a short list of the steps you need to do in order, these are explained in more detail after.

    1. Starting the machine
    2. Raising the platform
    3. Placing the material
    4. Calibrating the laser

Let’s start with 1. Starting the machine.

These explanations on how to set up the laser cutter will be based on the Trotec Speedy 400. Some steps might differ slightly depending on the specific laser cutter you’re working with. The steps are written in a more general sense that can be used across most of them. Please refer to the manual of the specific laser cutter for any differences.

Before doing anything, you should start by checking everything is plugged in; power cables for both the laser and the filtering system and the air conduit between the two. When everything is in order, you can turn on the switch.

Practical Tip
Some laser cutters will not properly start until they’re all reset to a default position. That action won’t work if the lid is still open. Make sure to close it and it should start resetting to the default position.

Picture by Lévi PONSARD

We can now move to 2. Raising the platform.

Since the platform will probably have reset all the way to the bottom, you’ll now need to move it back up. The laser cutter is supplied with a control panel. As you can see you’ll usually have four arrows to move the laser (in red) and two arrows to move the platform up and down (in green). These are the ones needed right now. You can raise the platform using those buttons until it’s at a sufficient height where you can place your material and still have room on top for the laser head. To know which material you can and should use, have a look at the second module of this learning material: Craft and material.

Practical Tip
Some laser cutters will have a way to keep raising the platform without holding down the button. Those are usually in the form of a “Shift” key (blue in the picture above) that you have to hold down then press the other key once. It’ll then repeat that action until it reaches the end.

Once done, 3. Placing the material is next.

Before placing the material in, make sure that you’re using the right grid on the platform. Refer to the maintenance part and how to change the grid if needed.

When placing the material in, it is good practice to get it “stuck” in a corner if possible. This allows you to be able to place it back again at the exact same position. You’ll have moments where you’ll need to replace the material at the exact same position again and this is a really easy way to achieve it.

Another important point about your material is going to be how straight it is.  If it’s not, you first should straighten it up if possible. If you can’t, you should try to secure it on the grid with either tape or a heavy object to keep it as straight as possible.

Important: Clear the pathway of the laser head
If you place a heavy object on top of your material to keep it flat, make sure it is not in the path of the laser head. Use something small enough so the laser can’t hit it. Remember to move the laser over it after calibration to make sure this is not a problem.
If the heavy object you are using is not small enough, make sure it will always be far away from the path. Know that the laser will move farther than the engraved part on either side, and that it may also return to an original position at a certain time – you’ll need to clear those paths as well.
If you are not sure that everything is okay, you should not try this, because you may damage the laser cutter.

Once the material is placed on the grid. You’ll still need to calibrate the height position for the laser. So let’s get to the next step, 4. Calibrating the laser.

As explained earlier, the laser is guided by the lenses to focus on a precise point. For the best and most precise results, this focus point must be exactly on the material.

Picture by Lévi PONSARD

Move the laser with the control panel, on top of your material. If the material is perfectly flat, you can use any part to do the calibration. If it’s not flat, you should move the laser to the part of the material you’ll be working on and start the calibration there.

Once the laser is positioned where it needs to be, you can start with the calibration. To help you with that task, the machine will come with a calibration piece, often a little piece of metal that allows you to set the exact distance between the laser head and the material to line up that focus point.

Place the calibration piece on the laser head, there should be a specific spot it slides on. The piece should also float a little bit over the material, if it’s already touching it, lower the platform and place the calibration piece again.

Laser head without the calibration piece (left) and Laser head with the calibration piece (right).
Pictures by Lévi PONSARD

You can now start to move the platform up, as you approach the calibration piece, slow down as much as possible and take small steps at a time to ensure that you do not overshoot the correct position. The calibration piece is built to fall off as soon as it touches the material. Remember to remove the piece from the machine before continuing!

Practical Tip

Auto calibration: Some laser cutters also have an automatic calibration of the laser height. For this, you simply need to place the laser in the correct position, as explained earlier, and then press the button provided for this purpose. On the control panel shown earlier, you can see the green coded buttons, both of which must be pressed on this model to trigger the automatic calibration. As you can see on the control panel, the letter “AF” is in the centre, which stands for “Auto Focus”.

Once the height calibration is done and the calibration piece removed, you can close the lid and move to the computer for the Software part of the setup.

Setting up the software

In this part, you’ll take a design, prepare it and send it to the machine software. In which you’ll learn how to set up the laser settings to attain the desired result. Here’s a short list of the steps you need to do in order, these are explained in more detail after.

    1. Preparing the file in Inkscape
    2. Sending the file to JobControl
    3. Setting up the laser
    4. Starting the job

We’ll use Inkscape as the design software and TROTEC’s JobControl as the machine software in this explanation.  Inkscape will be used because it’s a free and open source vector drawing surface that will be sufficient to design and prepare files very well to be sent to the laser cutter. However, other vector drawing software such as Adobe Illustrator or CorelDraw can also be used.

JobControl is the machine software that is needed to use the specific laser cutter we’ll be using in this specific course. Each laser cutter will have its own machine software. However, the information can also be transferred to other software.

Let us first open our design in the design software. For step 1. Preparing the file in Inkscape.

The first thing you should consider is which lines to cut and engrave. In other programs, such as CorelDRAW, the line width matters. This forces you to use the “Hairline” option so that JobControl recognizes it as a line. In Inkscape, however, every line is recognized as such, regardless of its width. This can lead to another problem, which will be explained later.

Let’s set the colour of the cutting line to a colour the machine software can use.

Here I’m using a perfect red, because the default settings in JobControl, and some other cutting software uses that colour as the default one to cut. Here’s some other colours you can also use, especially if you desire to have different settings while cutting or engraving a design:

Here’s all the different colours JobControl can use. While 16 colours might seem like few, these are only used if you want different cutting settings at the same time.

To make sure that the line is perfectly recognized as a line by the JobControl, the colour must be accurate, but you must also make sure that there is no transparency set on the object itself or in the colour alpha of the stroke. You also need to make sure that it is a flat colour and that there are no additional effects on the stroke. The cut line must be above everything.

In the “Stroke paint” tab, you want a flat colour of one of the colours said above ending with “ff” to make sure there’s no transparency. Then make sure the blur is at 0% and the Opacity at 100% at the bottom. In the “Stroke style” tab, make sure the dashes option is set to a straight line. While the width shouldn’t matter, I usually use 0.2 mm and have no issues with it.

Practical Tip
It is not necessary to check all these settings every time, as they should not change by themselves, but it is good to check them if you see that your line is not displayed correctly when you move your design to JobControl.

More so than the settings being “right”, you should always think critically about what the path of the laser is going to accomplish and what is going to be cut. Making sure things don’t get cut in half if you want them to be in one piece, making sure the parts don’t get too thin and break, etc.

Now that the cutting part is all setup, let’s get onto the engraved part. As mentioned earlier, Inkscape sends lines to JobControl as lines, regardless of their thickness. If you want the lines to actually be engraved and retain their thickness, you must convert them from a stroke to a path.

As shown in this example, the 4 stripes go from 4 thick strokes to 4 rectangles.

For more complex geometry and files, it might be easier to export all of the engraving part as an image, like a png, then import it back instead of converting all the strokes.

Exporting as an image will make sure the machine software views it correctly for engraving. It’ll also allow you to convert more complex effects such as blur or transparency. Those complex effects are very likely to not be understood correctly by the machine software and likely to break the file.

It’s also easier to work directly in grayscale for everything that’s going to be engraved, the darker something is, the stronger the laser will be. But it’s also possible to use the colours mentioned before to set them individually. For now, you can use any of those colours as they’ll be set up individually later on, when setting up JobControl laser’s settings.

Because of the nature of how the laser will burn the wood, it can be harder to see very small contrast and it might sometimes be better to give a lot of contrast to the images before engraving.

Pictures by Lévi PONSARD

Before sending the files make sure the dimensions of everything are correct, the size of objects as indicated in Inkscape will be what comes out of the laser cutter. Also make sure that everything that you want to send is in the workable zone, which is from the top left corner of the page, going down and to the right. Anything that is outside of that area will not appear when sending the design.

Anything in the red area around the page won’t be seen when sending the design to the machine software

Next, 2. Sending the file to JobControl. To send the design to the machine software, you need to use the “Print” option and select your particular laser cutter as the “printer”. Before continuing, make sure to view the preference of the laser cutter.

The size settings (1), is how much of the design will be sent to JobControl, these sizes won’t change the size of our objects themselves. You can either select “User-defined Size” from the drop-down menu and enter the width and height, you can select a default from the list, or you can also check “Take from application “, which will apply the page settings of the design instead. The “Minimise to Jobsize” will crop any empty space around the job itself.

Practical Tip

You can select “User-defined Size” and put in the maximum size that your laser cutter can handle. Uncheck “Take from application” and check “Minimise to Jobsize”. That way, you don’t have to change those settings between every job, It’ll always take the maximum size possible your laser cutter can handle, then reduce it to the job itself. Just be careful that by doing this, things that are under and to the right of the page itself in the document might still get sent as part of the job. As seen in the previous green and red picture.

The material settings (2), allow you to already select the laser settings for your job. These can, however , be switched in JobControl itself and will also be explained later.

The process options (3), will change how your design will be processed before it’s sent to JobControl. Most options here should be pretty self-explanatory or shouldn’t be switched from default.

The Colour options, however, need some explanation. As said earlier, for the engraving part of a design, you can either use shades of grey to have different intensities, or you can keep some colours.  If you keep the colours in the design, this is where you can select how they’ll be handled, if you choose “Color” in the drop down list, the software will assign colours from the usable colours in JobControl to your design. The other options will transform the engraving part to black and white pattern that’ll allow you to fake different shades.

The last two checkboxes (4) allow you to start the cutting and engraving process with “Quick print” and position the job automatically with “Auto position”. When everything is set correctly, click the accept button and print. This will open JobControl and send your design to the job list.

The “accept” and “cancel changes” buttons

Let’s have a quick look at JobControl’s interface:

At the top, in pink, we have all the settings, and more importantly, the laser settings.
In the middle in blue, we have a preview of our workplace.
In the left in red, we have an estimation of the time the job will take.
In the right in green, we have the list of the jobs that were sent to JobControl
And in the bottom right, in yellow, we have the machine control buttons to connect to the laser cutter, start and pause a job.

When first launching JobControl, the first thing you’ll have to do is to connect JobControl to your laser cutter, to connect it, click on the USB icon in the bottom right. If the laser cutter is turned on and the USB cable is plugged in, the laser cutter should now be connected and the USB icon should switch to a play icon.

By connecting the machine, you should also be able to see a cross somewhere in the workplace. This cross is a preview of where the laser is positioned on the machine itself.

This laser position is actually very helpful to position your job exactly where it needs to be. Instead of randomly placing the job on the computer, you’ll be able to make sure it starts where the laser is physically pointing on the material.

You can use the directional arrows on the machine’s control panel to position the laser where you’d want one of your job’s corners to be. Then back on the computer, you can see the updated position of the laser. You can now simply click and drag your job from the job list into the workplace, by getting the top left corner close to the laser position, it’ll automatically snap the corner exactly to that same position.

It is especially useful when working with an already used material and you need to avoid some areas that have already been cut.

Practical Tip

When a job is at the right position in the workplace, you can take a note of its exact position in X and Y value seen in the screenshot below. If for whatever reasons, you need to replace your job at the exact same position. You can use those two values to exactly place it back. This can be more precise than trying to reposition the laser at the exact same spot.

When selecting a job, either in the job list or on the workplace, you can see the job preview, this is a good place to double check that your cutting lines are working. You can also turn on the preview on the workplace itself by clicking the eye in at the top. If some lines do not display, it is either because they do not yet have settings for that specific line colour or there was a problem in the design that needs to be fixed before the file is sent to JobControl again.

Talking about the laser settings, let’s go to the next step, 3. Setting up the laser.

In blue you can see the settings that are currently selected and can quickly change the presets in the green dropdown menu.
You can also click on the material database, in red, to open the full laser settings window:

At the top, in green, is the currently selected material preset and in which material folder it’s stored. Those presets are stored in the left list, in red. By default, a lot of pre-sets are made for all kinds of materials, which are very helpful when starting to use a laser cutter. These default presets should give you a good indication of the kinds of settings that will work with each material.

Practical Tip

While it’s possible to just edit the default presets to match the desired result. It’s usually a better idea to create your own set of folders and presets for each of your specific uses. That way, keeping the default presets on their default settings means that anyone that uses the machine too will already be familiar with those default settings. To create new folders and pre-sets, use the two buttons under the list.

In pink, you have another setting button that allows you to export your material presets into a file or import some others. This can be very useful if you want to copy all your settings from one computer to another. These settings also allow you to change the processing order of colours or lock presets so they can’t be changed without a password.
Above the actual laser settings, some descriptive aspects of the pre-sets you have chosen are displayed in yellow. The thickness setting won’t actually impact how the laser operates and is just an indication for you to know which thickness those settings are set to cut. Any additional information you want to have about a pre-set can be written in the description. Finally, in blue, the laser settings themselves for the selected preset.

As you can see from earlier, all 16 colours are here on the left side, and for each colour, you’re allowed to change every setting of the laser. Let’s go over them one by one.

First, the “colour” column. As you can see each colour has a number attached to it, this number is actually the order of operation that the laser will go through. It’ll go through each colour, one at a time, starting with all the engraving ones then doing all of the cutting ones.

Secondly, the “Process” column. This is where you’ll set if a colour needs to be used to “Engrave”, “Cut” or if it simply needs to be ignored with “Skip

Practical Tip

As said earlier, if some part of the design were not visible on the workplace, it might be because the colour of that part of the design was set to “Skip” in these settings. If they weren’t, the problem is most likely on the design file itself and will need to be fixed before sending it to JobControl again.

Next we have the “Power” setting. This power setting will set how powerful we want the laser to be. The higher the number, the stronger it’ll be, the more material it’ll remove and the harder it’ll burn the material. The power setting in JobControl is set as a percentage of its maximum power, from 0 to 100. This means that 100 Power on the Trotec Speedy 400 will not give you the same result as on the Trotec Speedy 100 as this second one isn’t as powerful.

The “Speed” setting, as the name indicates, will be how fast the laser head moves around while engraving or cutting. This setting goes hand in hand with the power setting. The slower the speed, the longer the laser has time to remove material and the deeper it’ll get in. Both settings will usually have to be fiddled with to obtain the desired results. This setting is also set as a percentage of the particular maximum speed of the machine. As you can also see, the default set speed for the engraving is much faster than the one set for the cutting. At this much higher speed, the laser does not have enough time to cut the material, so it is only engraved. When switching between “engraving” and “cutting“, make sure that the speed and power are also changed accordingly.

The “PPI/Hz” setting is actually two settings that’ll change depending if the process of that colour is set to engrave or cut. While engraving; this setting is set to PPI, or Pulses per Inches. This is the definition of the engraved visuals. This can usually be set to “Auto”, as this will automatically set the PPI based on the definition from the exported design. While cutting; this settings change to “Hz”, which is the frequency of the laser pulse while cutting. The quantity ranges from 1000 to 60000 Hz. In the individual manuals you will find information on the appropriate frequency of use.

The “Auto” check box will simply set the PPI or Hz setting to be automatic if checked. A manual PPI can be used if you want to change the quality of the engraving manually, a lower number will also allow you to speed up the engraving process a lot. A manual frequency, with the “hz” setting, should be used when you’re switching to materials that require a different frequency to be cut.

Passes” is simply the number of times a colour will be processed. It can sometimes be better to use multiple passes to cut a thick piece or harder materials instead of lowering the speed a lot. One of the reasons being that the slower the laser is moving while cutting material, the more time it gives to the material to heat up and potentially start a fire.

Air Assist” can be turned on and off. When turned on, the machine will blow air to the material as the laser cuts it. This can help the result as it’ll blow away small particles. This should almost always be turned on.

Z-Offset” Will move the material up and down for each of the colours depending on this value. From -5mm (pushing the material up) to 25mm (pushing the material down). This can be used in case the material has different heights to be worked on while still having the laser in full focus. For example, if you have a bent piece of wood, you can have different colours assigned to different parts of the design to offset those differences on the bent parts.

Practical Tip

Defocusing the laser on purpose
This Z-Offset setting can also be used to defocus the laser on purpose to transform thin cutting lines into much wider lines for engraving purposes. Be careful that working with a defocused laser can be slightly dangerous, use a lower power and faster speed so you don’t risk starting a fire. This can also be achieved by manually lowering the platform on the laser cutter. However, this will need specific testing for each machine, as how much the laser’s radius will increase will depend on the machine.

Direction” allows you, for engraving colours, to select if it should be engraved from top to bottom or bottom to top. This does not have any impact on the finished piece but if you’d want to see a specific part engraved first so you can check if you have the right settings, you can switch here to change that order.

Path planning” sets the acceleration of the laser head, a fast acceleration like “throughput” will allow for faster job but may yield slightly worse results. On the opposite, the “Quality” option will have a slower acceleration and “standard” will be in-between those two.

Advanced” allows you to set some other advanced features. These are a bit outside of the scope of this unit. You can refer to JobControl’s information on the official web page here: https://www.troteclaser.com/en/learn-support/helpcenter/tips-laser-software-jobcontrol-vision

Now that you have a basic understanding of what every setting does, it’s time to set it up for your specific job. Again, starting from a pre-set that closely matches the material you want to work on is the easiest way to start. Past selecting a preset, there is not going to be a magic setting, to get the desired result, you’ll need to try some settings and change them around to see the different results for yourself.

If the cutting doesn’t fully go through, you’ll probably want to either turn the power up, slow down the speed, a combination of both or use multiple passes.

In the opposite situation, if the cutting goes through effortlessly, you might want to speed up the cutting process or turn down the power a bit. You generally want the cutting to be done cleanly. Turning the cutting settings too strong and slow will also result in more burnt edges. This is always going to be a balancing act. The same principles can be used for the engraving settings. Slower speed and higher power will engrave deeper and darker in case you’re using wood.

Important

While the settings here could be the cause of a problem, it’s also possible something like the height calibration was off. If that’s the case, the laser wouldn’t be well focused on the surface and create problems. Always make sure the calibration is correctly set.
Furthermore, if the result of the engraving is not up to par with the desired results even after trying different settings, it might be better to first modify the design like adding more contrast if needed, etc.

Don’t forget to save your settings as new presets for each material, thickness and desired results. You don’t want to re-do the same job as you’ve already done. When the settings are set, be sure to double check everything:

    1. The design being at the right spot. 
    2. The right colours have the right settings for cutting and engraving.
    3. The material being at the right spot in the laser cutter. 
    4. The laser is well focused on the material. 
    5. The lid being closed.
    6. And finally nothing in the path of the laser head.

When everything is good. The last step is 4. Starting the job. You can start the job by clicking on the play button. The laser cutter should now start the job, starting, as mentioned earlier, by all of the engraving parts and then finishing with the cutting. Monitor the process to make sure everything is working as intended. If something goes wrong then you can pause or stop the process to correct things. Wait for a bit after the job is completed to let any smoke inside of the machine get pulled out and filtered.

Post-Processing

In this part, you’ll learn how to remove the cut pieces, process them, combine them if needed, treat and paint them. When the job is fully finished, you can open the lid. Before starting to move things around, it’s a good idea to verify if pieces are completely cut out. To do so you can hold over the piece with one hand and then gently lift the material with the other without sliding it at all. If it hasn’t been cut, you can do another pass of the cutting lines to finish it.

This is also why it can be very important to lock the material into a corner, it makes it easy to keep it at the exact same position to redo a job. Being offset by even half of a millimetre is going to ruin the job.

When everything is in the desired result, you can remove the pieces from the laser cutter. Be wary of where you’re holding the pieces. Since the laser is cut by burning, some material like wood will be dirty on the edges and it’s really easy to smudge that all around the pieces if not careful.

Talking about this, you should always start by cleaning the pieces. A simple towel will do the job just fine, if the material is more water resistant than wood, such as acrylic, a wet towel will be even better. To clean the burned edges on wood, you can also use sand paper, this will, however, remove even more material and should be taken into consideration in the design phase if the pieces need to be assembled together.  You should also control the quality of the pieces for jagged edges. Those can usually be smoothed out with sand paper too.

Pictures by Lévi PONSARD

Important
You should work with gloves if you’re handling sharp material and the appropriate face mask if the material can emanate dangerous chemicals. For example, acrylic sheets or painted wood.

Before glueing everything together, you should try to assemble it all to see if everything fits together. Since the laser has a small radius, usually less than 0.1 mm when well calibrated, this means that the hinges will vary slightly, and this radius should be taken into account at the design stage if you want parts with a tighter or looser fit.

Don’t forget to use the right type of glue for the material you’re using and wear adequate hand and face protection. Using clamps to hold everything together while the glue is drying should help everything to stay at the right spot. Each type of glue has a different drying time indicated on the container itself. Make sure to wait a sufficient amount of time before handling the glued pieces.

Practical Tip

If your pieces tightly fit together, the amount of glue that is needed is very low. The pressure of the pieces pushed together will spread around the glue. That can usually make some of the glue spill out. Don’t forget to remove any excess before the glue settles in, as it could be much harder to do so after.

Pictures by Lévi PONSARD

Adding a coating or paint on the piece can be done before or after assembling. Each way has its advantages and is inconvenient. It can be much easier to add the coating on flat separated pieces, as when it’s assembled, it might create corners or other hard-to -reach places. The problem with doing that step before putting on the glue is that if some of that glue spills on the edges, it’ll now be visible over the coating or paint. If those layers are added after assembling, they can help hide them instead.

When working with untreated wood, you should know that it has a tendency to absorb liquids. That’s why you shouldn’t directly try to paint untreated wood, it’ll take a lot more paint to get to the right colour and it’ll damage the wood in the process. As already mentioned, there are several ways to treat wood: you can varnish it, paint it or just oil it. Regardless of which option you choose, you must first clean it. You can use a solution of TSP and warm water to do this. You can also use a TSP substitute.

Definition: TSP
TSP stands for Trisodium phosphate which is an inorganic chemical compound used as a cleaning agent, stain remover and degreaser.

When the wood is clean, you need to make sure it’s not rough, depending on the wood you cut, this might already be the case, if not, you can use 180-grit sandpaper to make sure of it. Then remove the dust with a vacuum cleaner. At that point, the wood is now ready to be treated.

If you wish to paint it, you first need to apply a primer layer of paint. This will allow the next layer of paint to stick and not get absorbed by the wood itself as said earlier. When the primer has all set, you can use sand paper again to get a smoother finish, this time use a finer grained one, like 220-grit and don’t apply a lot of force while sanding. Don’t forget to remove the dust with a clean brush and cloth. You can now paint over the primer with the final paint. For an even smoother result you can repeat the sanding process after that layer of paint and add a second one.

If you’d rather varnish it, first select the right varnish for your projects. You can choose how it looks; either glossy, mat or satin but also transparent or coloured. And more importantly, you can choose a varnish depending on its physical qualities; some are more durable than others and resistant to outdoors conditions. Some are easier to use and will dry faster. Same as with painting, you can alternate between adding a layer, letting it dry then sanding, removing the dust with a wet cloth, and repeating the process. You can use finer grit at each step until you get the desired level of finish. Three layers of varnish should be a minimum but you can get to 5-6 layers and up to 400+ grit sandpaper. Once the last layer of varnish has been added, you need to let the piece cure for one to several more days depending on the varnish used.

Maintenance

In this part, you’ll learn to maintain your laser cutter by cleaning the lens, changing the filters and also how to switch the grid. Maintaining your equipment is one of the most important tasks when using these kinds of tools. Not only it’ll allow you to avoid most incidents, but it’ll also keep you healthy and keep giving you the best results on your engraving and cutting.

The lens is a primordial part of the machine, and as such, it should be given special care. As the lens needs to be really close to the material being worked on, dust particles will land on it. As these accumulate, less light will be allowed through and the engraving or cutting results will suffer from it. This is one of the ways you should know that you need to clean it, but you should be cleaning it at regular intervals too. That interval could vary depending on the type of material you’re working with.

Example

If you’re engraving on a ceramic mug, this will create a lot of dust and will force you to clean your lens much more often. Cutting through leather will result in much less dust and of course, will take longer before the lens needs to be cleaned.

On average, after 8 to 10 hours of engraving, you should check and clean the lens.

Important: Before handling the lens
Before continuing and cleaning the lens, you have to be wary of the fact that the lens can easily be damaged if not handled with care and with the right tools.

You can start by blowing any lint or dust on the laser head with a blower or compressed air. Once the laser head is clean enough, prepare what you’ll need to clean the lens before removing it. That way you can minimise the time it’s out and limit the risk to damage it. If the laser cutter has its own lens cleaning kit, use it. Else, you can use a lens cleaning solution with some cotton swabs or some lens cleaning wipes. Do NOT use any random wipe or cloth as they could have a slightly abrasive surface that could scratch the lens. You should also equip yourself with gloves, both to protect your hands from the product you’ll use but also to protect the lens from being touched by your fingers. Also prepare a soft surface you’ll be able to put down the lens onto.

Picture from https://www.troteclaser.com/

Each laser cutter will have its own way of locking the lens in place, some might even allow cleaning it without completely removing the lens itself. In this example, on the Trotec Speedy 400, the ring under the lens first needs to be unscrewed to allow the lens to slide out.

Pictures by Lévi PONSARD

If the lens has a border, be sure to handle it by touching it and not the lens itself. If it’s on its own, only grab it by the edges. Avoid touching the lens itself. Make note of the orientation of the lens as you’ll have to insert it back on the same side. Use a little bit of the cleaning solution on the lens then gently rub it in with the cotton swab or the cleaning wipes. Both sides should be cleaned as they both can be in contact with the dust particles.   Make sure the lens is dry by going over it again with the cotton swab or cleaning wipe before inserting it back. To insert it back, just follow the previous steps you took to remove it but in reverse order.

The second most important part of a laser cutter maintenance is changing the filters. When these filters get full, the gases produced by the laser can start to leak. These gases can range from just being smelly to unhealthy. So changing the filters when needed is absolutely required when operating a laser cutter. There exist usually up to three kinds of filters that can be used with your laser cutter:

    • A pre-filter that can be used in between the laser cutter and the exhaust system. This pre-filter is there to catch the coarse particles to ensure a longer life span for the main filter which can also reduce the cost by lowering the rate of changes of the main filters.
    • The main filter, which will be responsible for catching most of the fine particles. This is the one you’ll need to change more regularly.
    • The activated carbon at the end of the filtering system will filter out most of the last hazardous fumes. This activated carbon takes a very long time to get saturated but is very important to change out once it is.

Most filtering systems will have an indication of how full each of the filters are.

Picture by Lévi PONSARD

The “Volume” is the volume of air the filtration moves per hour.
The “Filter” is how full the main filter is.
The “Activated Carbon” is how saturated the activated carbon is.

When a filter is approaching 100% of saturation, it’s time to change it.

Once again, the change will be explained for a particular filtering system; Trotec’s Atmos Mono. While some of the general explanations will apply to every system, the specifics of the process will differ. Refer to your particular system notice for the step by step guide. First step is to open the filtering system. To open the Atmos mono, you’ll need an Allen key to open the two locks.

Pictures by Lévi PONSARD
Picture by Lévi PONSARD

After opening, you can see the pre-filter mentioned previously, this one is only meant to capture quite large pieces that would have made their way through the exhaust pipes but other pre-filters can be added to further increase the lifespan of the main filter.

To be able to remove this pre-filter, you’ll first have to remove the exhaust pipes on the side. Then remove the pre-filter. As you can see, this pre-filter can get quite dirty and you can also clean it a bit before putting it back but there is no need to get it spotless, as it won’t take long for it to be dirty again.

Pictures by Lévi PONSARD

Under this pre-filter is the main filter, you can just lift it up to change it when needed. It is possible to clean it using compressed air to extend its lifespan but they’ll need to be actually changed for new ones after a while.

Pictures by Lévi PONSARD

Under this main filter is the last part of the filtering system, the activated carbon. This part only has to be replaced after a very long time of operating the machine. Usually in-between 1 and 3 years depending on how much the laser cutter is being used.

Picture by Lévi PONSARD

You might have to sometimes remove the grid of the platform. There can be several reasons to do so such as cleaning the grid, changing the type of grid for different projects or simply to access anything that would have fallen under the grid. Before touching the grid itself, make sure that the laser head is in a corner and lower the platform so the laser head won’t be an obstacle when removing the grid. When that is done, you can turn off the machine. The locking mechanism might be different for each laser cutter, for the one we’re using here, the Trotec Speedy 400, they’re located on two opposite corners. You can simply push them down and then release them to make them loose.

Pictures by Lévi PONSARD

When these screws have come loose, you can simply lift the grid and either clean underneath, clean the grid itself or change it to another one.

Picture by Lévi PONSARD, showing a bunch of smaller wood pieces that fell through the grid.

Summary

In this content unit, it was demonstrated what a laser cutter is, as well as what to use it for, how to operate it in a safe manner, how to post-process the pieces that come out of the machine and how to maintain the laser cutter.

The two main kinds of laser used were shown. CO2 lasers made by agitating electricity in a gas mix and fibre laser are amplified inside fibreglass. As well as the material that both of those can be used on, such as wood, acrylic, leather, stone and even metal for fibre lasers.

It’s always necessary to follow safety measures when working with a laser cutter. It’s important to know about the emergency stop button as well as which extinguisher you can use, dry powder or CO2 ones. You should also keep a first aid kit and a fire blanket nearby the laser cutter. 

It was illustrated how to set up the machine itself to get ready to receive a job by following these steps: 

    1. Starting the machine
    2. Raising the platform
    3. Placing the material
    4. Calibrating the laser
    5. Turning on the ventilation & Checking filters

 

How to prepare a file and send it to the laser cutter following these steps were also presented:

    1. Preparing the file in Inkscape
    2. Sending the file to JobControl
    3. Setting up the laser
    4. Starting the job

 

How to take wooden parts cut from the laser cutter and process them to a final piece by cleaning, sanding, painting, treating and glueing them together was shown as the post-processing part.

Lastly, it’s also important to know how to maintain the laser cutter by cleaning the lens, changing the air filter and the carbon filter when needed as well as changing the platform or cleaning underneath it. A well maintained laser cutter will work properly and safely for a long time.

Quizz