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LASER – CNC Maker Zone

Get started LASER cutting with GCoderCNC 2.5D

Banner for open this project in GCoderCNC 2.5D

If you’ve read the introduction to our GCoderCNC 2.5D web app you may be wondering how you can get started using it for some LASER cutting. If so, here’s a quick tutorial that should have you engraving a happy face onto some wood with only a few simple steps and a little time at your CNC machine.

Firstly, opening GCoderCNC 2.5D really is as easy as going to its’ secure website at Github.io. It should launch with the happy face design already loaded as shown in the screenshot below. To make life easy for you, just click here, or on the screenshot, to open the web-app in a new web-browser tab.

A screenshot showing how the web app looks when it launches

The app will have started up in router mode, whereas we’re doing some LASER cutting. That’s easily sorted, just go to the ‘CNC mode’ menu at the top of the app window and select ‘LASER mode’. There’s a screen-grab below showing the menu options. In case you’re wondering, the difference between the router and LASER modes is simply that router mode allows cutting tools to go up and down, and LASER mode keeps the LASER at the same height all the time. For advanced use you can actually use router mode for LASER cutting, using the depth to vary the laser height when cutting thick material. But for now, using LASER mode keeps things nice and simple.

A screenshot showing the CNC mode menu for changing between router and LASER mode

Next we need to tell the web-app what settings are relevant for our own LASER. That really comes down to your CNC machine and LASER module. For example, a 50W CO2 LASER will need much lower power to etch the surface of wood than a 2W diode-LASER. So, if you’re unsure, it’s best to read your manual or ask the manufacturer. I use a cheap Chinese 1610 CNC machine with a 5W diode-LASER, so I find a feed rate of 200 mm/min and 20% LASER-power works well for etching plywood. When you’ve decided, simply move the two sliders at the top of the ‘Default settings’ box, at the left side of the app, to the right values, as in the screen-grab below, keeping the other options unchanged.

A screenshot showing the default feed rate and spindle speed settings area

Now that the design is all set up we just need a g-code file for our CNC machine to follow. That’s really easy to get: just go to the ‘Export’ menu and select ‘Export G-Code…’ and the dialog box shown below will appear. You’ll notice that the width and height of the finished piece are already set to a default size. If you want the happy face to be bigger or smaller, just change one of those values (the other will change to keep the design proportional automatically).

A screenshot showing the export g-code dialog

Now you need to set the ‘GRBL version’ dropdown in the dialog. Older versions of GRBL (say v0.9-ish) used values of 0 to 1000 to represent 0% to 100% spindle motor speed, but more recent versions (say v1-ish) use values of 0 to 255. Don’t worry if that confuses you, as you should be able to find out from your CNC manual or manufacturer. If not, you can try selecting ‘Speed 0 to 255’ and, if your LASER seems to be etching too lightly (spindle speed values are used for LASER power too), you’ll know to use ‘Speed 0 to 1000’ instead. Having done all that you can click the ‘Download the G-Code’ button. Your browser should tell you that it’s downloading ‘happyface.nc’ which should end up in your downloads folder.

If you’ve done all the above then it’s now down to you to make your own happy face. Obviously the first thing you need to do is put some wood on your CNC machine: I used some 2mm thick plywood blanks I bought in Hobbycraft, but most woods should work. Once that’s done and you’ve focused your LASER (and still using LASER-safe glasses and ventilation) you need to move the LASER-dot to the lower left corner of the area you want to burn the happy face into: that’s the default origin and you can see what I mean in the image below.

A photo showing the position of the LASER moved to the origin of the design

Now, once you’ve turned off the LASER in your CNC control software, you need to zero your CNC axes in that software. That makes all of the g-code commands relative to that position, or the origin as we call it. If you’re not sure how to do that you need to read your CNC manual as it’s a really important thing to know how to do. And then it’s the exciting bit, where we tell the CNC software to burn/etch our design onto the wood. If all went well, you should end up with something like the one shown below 🙂

A photo of the smiley face design burnt into the surface of a small piece of plywood
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Making miniature 1/12th scale fruit crates

GCoderCNC 2.5D banner

Sometimes it seems like there’s no end to the range of projects we can make with a CNC machine. And it’s quite amazing that even cheap versions are accurate enough to make miniature projects for model scenery and even dolls houses. So I thought it might be fun to try making some miniature fruit crates, as the photo above shows, and post the design here for anyone to have a go at making some too. At full size they would be around 450mm long, 300mm wide and about 200mm high but at 1/12th scale, commonly used for dolls houses, they’re much smaller: I’ve included a photo below with a one pound coin for comparison.

A photo of the miniature fruit crates with a one pound coin for scale

I’ve put an SVG file below for you to download, or you can click here to launch it in the GCoderCNC web-app. If you need to edit it, or make a DXF file for your CNC software, you can do that with Inkscape quite easily. The red box is there in case you need to get scale in your software, but doesn’t need to be cut: it should be 70mm wide by 65mm high for 1.5mm thick wood (or other materials such as plastic, or even cardboard, if you prefer). If you use thicker material you can scale it proportionately, such as 2x scale for 3mm thickness. The design works for LASER cutting but can be adjusted easily for routing by offsetting the lines through half the cutting width.The SVG file of the fruit crates for cutting or editing in InkscapeI LASER-cut a prototype in Oak (the one on top in the photo above) and the rest in Basswood, both from 1.5mm sheets. Once cut they are quite simple to put together. I started by putting the sides onto the bottom of the crate, then slipped the ends on one at a time. I also used glue at all the push-in joints: the base could be left floating but the glue helps prevent the thin pieces of wood at the joints breaking away when sanding. To finish the crates off I used 400 and 1000 grit sandpaper, including using a finger sander, followed by a couple of coats of Danish Oil to give the wood a nice look without too much of a shine. Personally I’m quite happy with the results and hopefully you’ll enjoy making some on your CNC machine too 🙂

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Cutting gaskets from EVA foam with a diode-LASER

One of the great things about having a CNC machine is that we can make very professional looking projects whenever we want to. So sometimes we’ll want to add those nice details that make a project stand out. Things like, for example, gaskets between parts. Recently I had a need to cut a couple of 50 mm square gaskets for a 3D printed extractor project, for which I chose to use commonly available EVA foam sheet. So I thought I’d write a quick post to let you know how that went with my diode-LASER and whether EVA foam is useful for low-power LASER-cutting on a CNC router.

As you can see from the photo above, my 5W diode-LASER module cut right through the sheet easily with the power set to 25% and a feed rate of 200 mm/min. I’ve cut EVA in the past with a 1500 mW LASER module too, so those settings sound quite comparable and show that low-power LASER’s cut EVA well. At those settings I didn’t find any burning of the foam, and the shape came out pretty much as planned with just a little shrinkage at the edges. Plus, as the photo below shows of the MDF sheet I cut the EVA foam on, the LASER energy left after it had passed through the sheet was small: although probably I could have used a lower LASER-power just as well.

A photo of the laser cut EVA foam gasket together with a photo of the limited damage to the underlying MDF sheet

If you decide to LASER-cut some EVA too, please remember to use lots of ventilation as the fumes are unpleasant: given the small amounts of fumes you’re likely to create you may be tempted to skip the ventilation, but be warned that there have been reports of some EVA foam containing chlorine, which could make the fumes quite hazardous. So please make sure the foam you use is safe for LASER-cutting and use plenty of ventilation just in case 🙂

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Cutting 1.5mm Cherry wood with a 5W diode-LASER

Cherry is one of those woods we all recognise, mostly by the distinctive colour and beautiful grain. We’re likely to find many uses for it in CNC projects, so I decided I wanted to try cutting some 1.5 mm Cherry sheet with my 5W diode-LASER to see how easy it would be. As you can see from the photo above, the Cherry sheet (with a water content around 9%) was actually quite easy to cut through with a LASER, on a par with similar tests I’ve done with Basswood, Walnut and Oak. The photo below shows the back of the cuts and it’s obvious that too much power, either from a high LASER-power or multiple passes, leads to considerable charring. However, for my use one pass at 75% power, and a feed rate of 100 mm/min, seem to give quite acceptable LASER-cutting results.

The back of the cherry sheet after laser cutting

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Cutting 1.5mm Oak with a 5W diode-LASER

Oak is a widely used wood that crops up time and again in things like furniture and traditional building techniques. It has a distinctive look and feel, making it something that we’re likely to want to use in a CNC machine sometime. So I decided to try cutting a 1.5mm sheet of it with my 5W diode-LASER mounted on my CNC. The results are in the photo above and you’ll notice that it was relatively easy to cut (much easier than, say, Mahogany), with one pass at 75% LASER-power and a feed rate of 100 mm/min being useful settings for future cutting work. As you can see in the photo below, using a higher power, or multiple passes, can result in more charring around the edges. The Oak had a water content around 11%, after being kept indoors for a few weeks, so wasn’t overly dry or damp.

The back of the laser cut oak sheet

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Cutting 1.5mm Walnut with a 5W diode-LASER

Walnut is a beautiful and widely used wood that should enhance any CNC project. For that reason I was quite keen to see how well my 5W diode-LASER can cut through a 1.5mm sheet of it. Obviously thicker sheets are available but for small projects I find thin sheets are very useful. Besides, cutting thin sheets gives a good idea of how well we can cut thicker ones too. The sheet I used here had a water content of around 10%, according to my small meter, so the results were likely not too affected by the wood being overly dry.

So, above is a photo of my cutting test at a feed rate of 100 mm/min, which I find a sensible speed for a low-power LASER on a small CNC machine. I was quite surprised as it was much easier to cut through 1.5mm of Walnut than for the same thickness of Mahogany. In fact, it was cut cleanly through at 80% power in just a single pass. It also didn’t burn excessively or flame, which was a bonus making it easy to work with. And, as the photo below of the back shows, it cut with fairly minor cleanup work required.

The back of the walnut laser cutting test

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Holder for 12mm diameter LASER-diode module

I have a couple of 12mm diameter 1500mW laser modules and heatsinks, plus a cheap Chinese CNC router. However, fitting the lasers is difficult as the heatsinks don’t fit properly into the spindle motor holder. Also, the laser modules are 5V, whereas my CNC only provides a 12V PWM laser output. So, I designed this 3D printing project to hold the laser module and a small power step-down circuit that would fit properly in place of the spindle motor.

You can download the 3D printing files by clicking here, including the OpenSCAD file for customisation as modules, heatsinks and mounting holes may differ for your laser. Also, it can be modified to add a small fan if necessary, to cool the laser when used continuously for a long time. For anyone interested: the step-down circuit is just a 7805 voltage regulator with a 10uF electrolytic capacitor on the 5V side, because the laser module has its own driver circuitry. You can see it in the photo below. Surprisingly for a simple circuit, it seems to work very well so far with GRBL control, but please use that circuit at your own risk.

Inside the LASER holder

Finally, a couple of construction notes in case they help:

  1. I tied a knot in the cable under the lid for strain relief. As the knot is bigger than the hole in the lid, if the cable is accidentally pulled the knot stops it breaking off the circuit board.
  2. The disc part with cutouts is a spacer that sits on the rim above the laser module. It allowed me to keep the circuit, which I glued onto it, away from the module.
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A simple LASER extractor project

This is a simple 3D printed design I came up with to extract smoke and fumes on my cheap Chinese CNC machine when LASER cutting. Basically it consists of a small collector to fit under the z-carriage (with a holder to glue onto the collector) and a couple of parts to adapt a PC fan to fit standard plastic hoses. The collector, once glued onto the holder, should fit the bottom of the z-carriage as shown in the photo above. It’s designed to be removable for when the CNC is used for routing. The z-carriage on my CNC seems a common design, so hopefully this should work on many CNC machines. The inlet and outlet parts need to be glued onto a 12V PC cooling-fan like in the photo below.

From the outlet I attached a 32mm plastic aquarium hose, the end of which goes out of a nearby window. Between the inlet and the collector I used a bit of 20mm rubbery plastic plumbing hose. Despite the design not being optimised for aerodynamic properties, it does remove most of the smell of smoke away through the window. It’s not perfect though as draughts can result in smoke not getting sucked away. I got around that by making a shield to go around the front and sides of the laser to help make sure smoke and fumes get into the collector. If you want to print your own you can get the 3D printing files by clicking here, including the OpenSCAD file in case you need to make any changes.

The extractor fan pump with 3D printed parts and hoses

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Adding a shield to a CNC-mounted LASER module

My LASER is an attachment for my cheap Chinese 1610 CNC router so it isn’t tucked away inside a metal case with a tinted window. That means I have to wear LASER-safety glasses whenever it’s running, which can be annoying if I’ve got other things to do. So I designed this simple 3D printed shield with dark red windows (as the LASER is blue). It comprises a small frame that slips onto the LASER module (with a hole for a screw if needed to stop it sliding down) and a three-sided shield that slides onto the edge of the frame, as shown below.

3D view of the laser shield assembly

After 3D printing the front and two sides need to have dark red plastic glued in: I cut mine from a plastic square photography filter I picked up cheap on eBay. Then those three pieces need gluing together at the front corners to make the shield. If you want to add some rigidity then there’s also a bottom component you can stick below the three sides. The shield is then easily removed for when you want to focus the LASER or for removing cut materials. You can download the 3D printing files from Thingiverse by clicking here, and in case you need to make adjustments that includes the OpenSCAD file. The shield also works well with my LASER extractor project, localising the area it extracts air from, which is one reason why the bottom plate is included in the design.

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