If you’ve searched the internet about laserable materials you might have decided that plywood is the most popular sheet material out there. And, you might be right which is no surprise given that it’s a very versatile material due to its strength and the solid-wood look of its surface. However, the glue used to bond the layers (i.e. the plys) together can give off noxious and toxic fumes when burned, and is also difficult for a laser to cut. Also, the glue and its thickness can vary around the sheet, making cutting potentially inconsistent.
That’s why using a LASER mounted on a CNC machine means we really need to make sure the plywood we use is LASER-safe. LASER-safe plywood has a special glue that reduces the fume problems and is easier and more consistent to cut. So, to see how useful it can be with my 5W diode-LASER I tested cutting a piece of 3mm thick LASER-safe Birch plywood. The results are shown in the photo above. I found that two passes, at 100 mm/min, around 100% power was successful at cutting right through.
However, probably due to variations in glue thickness, and some curving of the sheet (and maybe water content variations: my meter said 8% although it’s hard to be sure with plywood) for some cutting I find I really need three passes. Below is a photo of the back of the test sheet, which showed that cleaning up the burn marks isn’t a small job, but nonetheless isn’t so bad that it’s not worthwhile.
Sometimes it’s nice to push the boat out and work with a nice (but obviously sustainably produced) hardwood on a special project. Once the staple of work and school desks, and plenty of furniture, Mahogany is an obvious choice for that, having a lovely dense feel and beautiful grain. So I decided that I should test some 1.5mm thick Mahogany to see just how easy it would be to cut it with a 5W diode-LASER. You can see the results in the photo above.
As the photo shows, the LASER has no real chance of cutting through in one pass, but at a feed rate of 100 mm/min, at approaching 100% power, two passes did the job. According to my meter that was with a water content of 12%. However, it does leave quite a bit of charring to clean away, although, as the photo below shows, it wasn’t so bad that it could be considered a game-stopper.
So, as with many other materials, cutting a mirrored version, so that the back becomes the finished front face, could be a good option. But, to give a good idea of how well you can cut quite detailed items out of Mahogany sheet, here’s a photo of a 30mm high Santa figure I cut at 100% power, 100 mm/min feed rate and two passes. Personally I was quite happy with the results.
Basswood is one of the most versatile woods I’ve found for CNC routing and low-power LASER cutting. And, when starting out in the world of CNC Making, I think it’s one of the most exciting too. The reason I say that is that you get a ‘real wood’ feel and ease of cutting more than just thin sheet. Why bother wasting time trying to cut through a couple of millimetres of plywood, which really doesn’t want to be cut, when you can cut shapes out of 6mm Basswood instead!
So why do I praise it so highly? Well, for one thing it lets you use thick and thin wood to make whole structures quickly. Also, it allows for easy cutting out of routed designs. Mostly though it’s because it significantly extends what you can do with a low-power diode-LASER setup on a cheap CNC machine. And above there’s a photo of my cutting test to show what’s possible with this wood which, according to my meter, had a water content of 11%.
Obviously it takes quite a bit of work to cut through a whole 6mm, but as the photo shows it is possible with three passes at 100% power on my 5W LASER. Also, the quality of the cuts was much better than I’d expected, meaning it’s possible to make some nice, fairly detailed, parts from fairly thick wood. Below is a photo of the back of the cutouts and, as you’ll see if you look closely, the back should be ready to clean up without too much effort sanding, which is a nice bonus.