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.
There are many choices for wood to use in CNC projects, and just as many ways to add a surface finish. But, whichever choices you make on materials and finishes the important thing is that we’re trying to bring out the beauty of the wood colour and grain structure. It’s perhaps one of the big joys of working with wood that it can start off looking really quite plain, even dull, but change completely with a little bit of loving care finishing it off. So, I thought I’d write a post about Danish Oil as I find it a very easy and effective way to bring out the traditional look of hardwoods.
A definition of Danish Oil is hard to pin down, as there’s no set recipe, but it’s usually around a third varnish and two thirds oil (click here to read more on Wikipedia). That means it needs to be mixed-well before use and dries hard, so can be used with or without a later clear-coat. It can also be bought with lighter and darker stains mixed in, to help give a variety of finish effects, so is very versatile. Personally I like to use the natural version, which has very little stain in it, to retain the natural beauty of individual bits of wood.
As an example, below is a photo of my routed Mahogany fish before and after finishing. After a light sanding (very important to open up the surface for a good oil finish) it had two coats of Danish Oil applied simply using a bit of cloth to rub it in. Once dry I added some gold enamel paint to the routed grooves to add detail and then the fish was very lightly sanded to remove over-paint and give a smooth finish. That’s all the finishing it had and hopefully you’ll agree that it looks a lot nicer than it did before.
Another example I can give is the photo below of my Walnut Darth Vader head routing project. The image on the left is before finishing and, even though the Walnut already looks good, it was rather plain. To get to the look shown in the right-hand image it had two coats of Danish Oil, and a light sanding when dry, to bring out the grain and the beautiful colours. The gold enamel paint was then added to the grooves, as doing it before the oil can make the gold look duller because of the small amount of stain in the oil (which sometimes can be a nice effect, but not for this project). I then gave it three coats of Plasti-Kote spray on clear-coat as I wanted a shiny finish. Then, a couple of red Swarovski crystals added a bit of sparkly bling to the eyes.
Hopefully you’ll have enjoyed seeing the hardwood projects above come to life using simple finishing techniques. If so, perhaps you’ll think Danish Oil something worth trying out on one of your projects too 🙂
If you’ve added a Bluetooth wireless module to your CNC machine, you might be thinking of using an Android tablet, or even a smartphone, to do some wireless routing or LASER cutting. If so, you may be wondering what software to choose. So I thought I’d write a short post about my favourite go-to Android app for controlling my CNC machine: G-Code2GRBL which is available on the Play Store. While I can only give my personal opinion, I find it excellent. It gives all of the functions I need in a nicely designed interface, as the screenshot below shows.
Once connected over Bluetooth to your CNC, G-Code2GRBL gives you a range of screens to choose from. The main ‘GRBL Control’ screen gives you buttons for jogging the XYZ axes (with step adjustment controls), buttons to zero XYZ positions, pause/reset buttons and a text-display of the GCode file being sent for routing/LASERing. The file to be sent can be chosen from the ‘Select files’ screen with just a few taps, which is nice. And another useful screen is the ‘Send Commands’ one. It lets you send your own one-line GCode commands for simple control, which is very handy for things like turning on a LASER (on low-power, obviously) for focussing, and turning it off again. Overall, I think it’s well worth a look if you’re after a way to control your CNC wirelessly from Android devices.
Recently I bought some 1.5mm thick Walnut sheet as I wanted to try it out with my CNC router and see how good the results would be. Walnut is quite a dark wood with a nice dense grain, so it seemed like an excellent opportunity to take my CNC intergallactic by making a small inlayed Darth Vader from Star Wars. Hopefully George Lucas will approve if he happens by, so below is my completed Darth Vader head (at around 10% water content, in case you’d like to know).
I was quite pleased with the results, the details being routed to 0.75 mm deep in two passes, and the edge being cut in three passes, using the 1.2mm diameter end-cutting bit shown above (which gave finished grooves almost 2 mm wide). As the image at the top of this page shows, the Walnut sheet cut quite well and cleanly with the spindle at 1000 rpm and a feed rate of 50 mm/min to minimise potential breakage of the bit. The above photo is then after I’d given it some sanding with a fine grit paper, which took little work. Even sanding out the recesses with folded over sandpaper was quite easy, with a little patience. So overall I’m looking forward to some more small projects using this lovely wood.
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.
CNC routers are wonderful machines for cutting and shaping wood and other materials but sometimes there’s no choice but to use a router without computer control. For example, when trimming the edges of wood to size, or for using the router as a finisher with sanding drums. When that kind of work is needed I don’t want another machine: rather I want to use my CNC router for occasional manual feeding. To do that a fence is very useful, as it allows pieces of feedstock to be pushed past the tool/sander in a straight line. Not only can that help ensure edges are kept parallel, but it also allows creation of small mouldings with edge-shaping bits.
This 3D printing project is my attempt at creating a very simple fence system for my cheap Chinese CNC. The fence part simply slides into the groove along the top of the CNC bed, after light sanding to get a good fit that doesn’t wobble. However, for manual feeding we don’t want the fence to be able to move along the bed groove, so a part is included for a simple stop that can be used to prevent that happening. The stop connects to the side of the bed using a winged hold-down nut as shown in the photo below. You can download the 3D printing files by clicking here, including the OpenSCAD file for any adjustments you’d like to make.
Hopefully you won’t mind if I finish with a word of caution. But, using a CNC router for manual feeding of materials brings risks you may not be experienced with. Probably two of the main ones are the dangers of having hands near your tool/cutter (which can be avoided using a proper push/feed stick) and extra dangers of pieces of tools and feedstock breaking and flying away (which can be largely avoided by feeding slowly and wearing sensible clothes and eye protection).
Another rookie error is to feed material with the rotation of the tool, which means it could unexpectedly get pulled through and shoot out like a javelin (I did that on a router table years ago and it’s amazing how fast the expelled material can be). Not only is that dangerous: it can even ruin your work. You may also want to wear ear protection as the sound level will be higher working close to the motor and tool. Basically, please be very careful and don’t take chances using the 3D models provided here 🙂
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.
