It’s Easter season in CNC-land, so I thought I’d have a go at designing an egg themed project. Of course, the most famous egg is probably Humpty Dumpty, and he’s also a nursery rhyme character so a fun project even if you don’t do Easter celebrations. So I came up with a simple design that can be LASER-cut from thin wood sheet on a CNC machine even with a low-power diode-LASER. I also decided to make the design symmetrical, and add a small registration mark in the lower-left corner, so it can be cut and engraved one side, flipped over without removing the sheet, and just engraved on the back. The finished project is shown in the photo below.
As you can see in the photo, I cut two versions from 6mm thick Basswood around 80mm high (using my GCoderCNC 2.5D web app – click here to launch this project there). That turned out to be a good size as I’d cut them at 90% power and 100 mm/min feed rate with 4 passes, so small areas of burning next to lines didn’t spoil anything and were easily sanded away. If you look closely you’ll notice that the engraved lines in the right-hand version are slightly mis-aligned. That’s because I made them two-sided: so I was quite happy that they turned out looking OK on the rear.
The smaller version was cut from 1.5mm Cherry wood, at the same LASER settings but just two passes. It’s smaller but turned out quite well, with just some charring around the eyebrows that was hard to remove. The Cherry was a little thin as the legs and arms were narrower than the larger Basswood versions, so I cut two and stuck them together with wood glue for added strength. Overall though, for a quick design I was quite pleased with the results, and I hope you enjoy making one too 🙂
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.
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.I 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 🙂
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.
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 🙂
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.
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.
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.
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.
Finally, a couple of construction notes in case they help:
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.
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.
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.
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.
1500mW LASER diode modules are a very inexpensive accessory for cheap CNC machines, and are ideal for things like burning images and text onto wood. However, with a little care they can also be used for cutting thin materials. One of those materials that is likely to be widely used, especially when crafting or carding, is white paper. So I decided to see if I could cut some white paper, which was around 80 gsm (grams per square-meter) and came from a notebook.
Being white and fairly smooth it’s actually quite difficult to cut as it reflects a lot of the LASER energy. But with some care focussing the laser dot to be as small as possible, and adjusting the height of the LASER (as they often have short focal lengths so shouldn’t be too high), I was able to do quite a nice cut as shown in the picture above (100% power and 100 mm/min). Fortunately, the dot on the 1500mW LASER is quite small so I thought it could be fun to see how small I could cut out my dragon and the result is in the photo below: at less than 20mm wide the cut quality was still quite good.