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 🙂
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.
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.