MDF (a.k.a. medium density fibreboard), just like plywood, is a very popular material in LASER cutting circles, largely due to it being a stable and relatively strong sheet material. Its stability comes from the use of wood fibres set in glue and means its less likely to bow or warp compared to plywood. So it’s likely any CNC user with a diode-LASER will want to cut a piece sometime. However, it’s important to note that burning glue, and released wood fibres, can be hazardous to your health. For that reason the MDF sheet I used here, with my 5W diode-LASER, is a LASER-safe version with less hazardous glue: although care is still needed to avoid inhaling anything nasty. Below is a photo of my cutting test.
The main thing the photo shows is that cutting fully through 2mm of MDF is possible with two passes, at a feed rate of 100 mm/min, on full power. However, a second thing to notice is that the MDF burned heavily (with a small flame) especially after the first pass had blackened the surface. That’s likely due to the glue and the slow feed rate needed for a low-power LASER. So care is needed to avoid fires and multiple passes will require a lot of work to clean up. Most likely cuts will need to be offset slightly when designing, so that the edges can be filed or sanded back to clean material, although back faces were cleaner as the photo below shows. Overall then, MDF may be useful for some larger, low detail, pieces, or for faster feed rate engraving, but on the whole it’s not something I’ll risk too often.
Basswood, like Balsa, is a go-to material for many Maker projects. Unlike Balsa, Basswood is a little lighter and denser and so has many uses in structural and non-structural parts of scenery and model making. So LASER cutting 1.5mm sheet Basswood is likely a common need. For that reason the photo below shows the results of a cutting test with my 5W diode-LASER attached to my CNC machine, with the wood having a water content around 8%.
All of the cuts are for one pass, so you can see that there are various options for quick cutting. personally I prefer to cut quicker to save time and slightly reduce surface burning, so a single pass at a feed rate of 200 mm/min, at a power between 80% and 100%, seems the best option for me. Also, as the photo below shows, the back is quite cleanly cut and not in need of a lot of cleaning up and sanding.
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.
Balsa is an amazingly versatile wood widely used in hobby making. If you’ve seen it nowhere else you must have seen many model planes flying around that are made from it. So cutting Balsa with a LASER is possibly something we’re all quite likely to want to do with our CNC machines sometime. To that end I’ve tested cutting some 0.8mm thick Balsa with my 5W doide-LASER mounted on my cheap Chinese 1610 CNC, and above is a photo of the results.
I chose a feed rate of 200 mm/min as I find going faster gives better edges to cuts. However, the Balsa burns quite easily leaving thick black lines around the edges. I tested the Balsa with my moisture content meter which said 8%, so the burning doesn’t seem to be due to the wood being overly dry. However, the cuts are quite clean and it seems that a single pass at 100% power is likely to work acceptably for my purposes most of the time. Of course, what happens on the back is just as important, so here’s a photo of that too.
It seems that the back is cleanly cut and the burning at the edges is less noticable than on the front. In fact, I’d say that, where possible, it could be better to cut a mirrored piece, so that the back can be used for visible edges that can be more easily cleaned up with light sanding. But, probably the most important outcome of my test is that thin Balsa is definitely a material that’s suitable for low-power diode-LASER cutting on a CNC.