Making a fun Humpty Dumpty Egg LASER-cut decoration

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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 🙂

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Make a GRBL CNC pendant with a Bluetooth data link

If, like me, you like to spend time surfing the internet looking at photos of CNC accessories, you’ve probably thought how nice it would be to have a pendant (i.e. a controller on a cable) for cheap Chinese CNC machines using GRBL controller boards. In fact, I wanted one so much I decided to build one to allow me to jog and zero axes, as well as to let me turn the LASER on for focusing and accurate jogging. I decided to do it using an ESP32 microcontroller as it allows the pendant to act as a Bluetooth link for G-Code sending/receiving as well. I thought my finished design might be useful for others to base their pendant designs on too, so I made it open source, and you can see what it looks like in the photo below.

A photo showing the finished pendant as well as the inside and a view of the circuit board.

It’s important to note that this could probably be described as an advanced maker project, as it requires skills with 3D printing, circuit making, soldering and Arduino coding. But if you’re up for the challenge you can get all of the files and details needed on Github and Thingiverse. The links are below and good luck making one as they can be an invaluable CNC accessory 🙂

3D files on Thingiverse:

https://www.thingiverse.com/thing:3521653

All files, including code, on Github:

https://github.com/drandrewthomas/ESP32_GRBL_CNC_Wireless_Pendant

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3D printing an 80x80mm extractor fan housing for LASER cutting

LASER cutting on a cheap and cheerful CNC machine is lots of fun, but I can’t say the same about the smoke and fumes. That’s why I posted before about a simple extraction system. But since then I decided to try to do better using a larger fan mounted on the CNC’s 2020-extrusion frame. So I used OpenSCAD to make a design based around an Arctic Air 80x80x25mm PC fan, as it’s designed for higher airflow than cheaper fans. You can see the result in the photo below.

A photo of the extractor fan housing mounted on the CNC frame during LASER cutting
The extractor fan housing mounted on the CNC’s 2020-extrusion frame

The design did quite a good job and the air flow-rate was quite impressive in my opinion. However, it has the disadvantage of covering a large area so the suction around the LASER-cutting area turned out less than for my previous design. So I decided to adapt the design to allow the fan housing to be mounted to a simple enclosure I’m prototyping for my machine. That led to me adding side supports that stick to the housing and have flanges with holes for bolts.

Using the fan with the enclosure works really well, with hardly any smell of smoke or fumes coming out while LASER-ing, as it’s all blown through a flexible 60mm hose out through a nearby window. You can see the side supports in the 3D assembly picture below. And, if you’d like to have a go at making your own extractor fan from this design, click here to go the Thingiverse page which includes all the STL files and the OpenSCAD design file too.

A 3D image of the assembly of the parts used to build the extractor fan housing and mountings
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Get started LASER cutting with GCoderCNC 2.5D

Banner for open this project in GCoderCNC 2.5D

If you’ve read the introduction to our GCoderCNC 2.5D web app you may be wondering how you can get started using it for some LASER cutting. If so, here’s a quick tutorial that should have you engraving a happy face onto some wood with only a few simple steps and a little time at your CNC machine.

Firstly, opening GCoderCNC 2.5D really is as easy as going to its’ secure website at Github.io. It should launch with the happy face design already loaded as shown in the screenshot below. To make life easy for you, just click here, or on the screenshot, to open the web-app in a new web-browser tab.

A screenshot showing how the web app looks when it launches

The app will have started up in router mode, whereas we’re doing some LASER cutting. That’s easily sorted, just go to the ‘CNC mode’ menu at the top of the app window and select ‘LASER mode’. There’s a screen-grab below showing the menu options. In case you’re wondering, the difference between the router and LASER modes is simply that router mode allows cutting tools to go up and down, and LASER mode keeps the LASER at the same height all the time. For advanced use you can actually use router mode for LASER cutting, using the depth to vary the laser height when cutting thick material. But for now, using LASER mode keeps things nice and simple.

A screenshot showing the CNC mode menu for changing between router and LASER mode

Next we need to tell the web-app what settings are relevant for our own LASER. That really comes down to your CNC machine and LASER module. For example, a 50W CO2 LASER will need much lower power to etch the surface of wood than a 2W diode-LASER. So, if you’re unsure, it’s best to read your manual or ask the manufacturer. I use a cheap Chinese 1610 CNC machine with a 5W diode-LASER, so I find a feed rate of 200 mm/min and 20% LASER-power works well for etching plywood. When you’ve decided, simply move the two sliders at the top of the ‘Default settings’ box, at the left side of the app, to the right values, as in the screen-grab below, keeping the other options unchanged.

A screenshot showing the default feed rate and spindle speed settings area

Now that the design is all set up we just need a g-code file for our CNC machine to follow. That’s really easy to get: just go to the ‘Export’ menu and select ‘Export G-Code…’ and the dialog box shown below will appear. You’ll notice that the width and height of the finished piece are already set to a default size. If you want the happy face to be bigger or smaller, just change one of those values (the other will change to keep the design proportional automatically).

A screenshot showing the export g-code dialog

Now you need to set the ‘GRBL version’ dropdown in the dialog. Older versions of GRBL (say v0.9-ish) used values of 0 to 1000 to represent 0% to 100% spindle motor speed, but more recent versions (say v1-ish) use values of 0 to 255. Don’t worry if that confuses you, as you should be able to find out from your CNC manual or manufacturer. If not, you can try selecting ‘Speed 0 to 255’ and, if your LASER seems to be etching too lightly (spindle speed values are used for LASER power too), you’ll know to use ‘Speed 0 to 1000’ instead. Having done all that you can click the ‘Download the G-Code’ button. Your browser should tell you that it’s downloading ‘happyface.nc’ which should end up in your downloads folder.

If you’ve done all the above then it’s now down to you to make your own happy face. Obviously the first thing you need to do is put some wood on your CNC machine: I used some 2mm thick plywood blanks I bought in Hobbycraft, but most woods should work. Once that’s done and you’ve focused your LASER (and still using LASER-safe glasses and ventilation) you need to move the LASER-dot to the lower left corner of the area you want to burn the happy face into: that’s the default origin and you can see what I mean in the image below.

A photo showing the position of the LASER moved to the origin of the design

Now, once you’ve turned off the LASER in your CNC control software, you need to zero your CNC axes in that software. That makes all of the g-code commands relative to that position, or the origin as we call it. If you’re not sure how to do that you need to read your CNC manual as it’s a really important thing to know how to do. And then it’s the exciting bit, where we tell the CNC software to burn/etch our design onto the wood. If all went well, you should end up with something like the one shown below 🙂

A photo of the smiley face design burnt into the surface of a small piece of plywood
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Create G-Code online with the GCoderCNC 2.5D Web-App

Creating g-code files for CNC machines is an essential task for our computer-controlled routing and LASER cutting projects. However, most CNC software packages are either overly complicated or limited to a single platform and operating system. So, to help avoid those issues CNC Maker Zone UK has published its’ own free-to-use and open-source web-app designed for ease-of-use on all PCs and tablets (but not smartphones) including on Windows, Linux, Mac, Chromebook and Android in a HTML5 web-browser.

Below is a screen-grab showing what the web-app, which is called GCoderCNC 2.5D, looks like running in the Chrome web-browser on Windows, with our Darth Vader Head project open (click the image to go straight to the web-app in a new tab). It’s designed as a web-capable app so if you add it to your home screen, in the web-browser menu, you should be able to run it in its’ own window, which is especially exciting when using it on a tablet. And, it’s been designed to create g-code for routing and LASER-ing, and even has some advanced features like variable routing depth for v-carving.

An example screenshot of the web-app running in Chrome with the Darth Vader Head open for editing

GCoderCNC 2.5D allows you to import an SVG file and export it as a g-code file, all without cookies or uploading your files to the internet: it’s all done on your computer in your web-browser. It’s intended to be usable and useful for anyone interested in CNC making, so hopefully you’ll find it works well for you once you’ve played with it and learnt the basics of its’ use. So, finally, here’s a couple of links to help get you started using GCoderCNC 2.5D:

The project on Github.com: https://github.com/drandrewthomas/gcodercnc2d5

The Web-App on Github.io: https://drandrewthomas.github.io/gcodercnc2d5

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Making miniature 1/12th scale fruit crates

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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.

A photo of the miniature fruit crates with a one pound coin for scale

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.The SVG file of the fruit crates for cutting or editing in InkscapeI 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 🙂

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Choosing a wood finish to enhance colour and grain

After all the love and care we put into our CNC projects their success often hinges on how well we finish the exposed wood surfaces. Sometimes we may just want to leave them plain, even unsanded, but usually we’ll be wanting to bring out the colour and grain structure to show off the beauty of the wood we’ve chosen. So what is the best way to do that? Should we just cheat and use clear-coat, or should we use traditional techniques like Danish Oil or Shellac sanding sealer? How much work is involved varies a lot depending on which we choose, so is the best way the one that involves the most perspiration, or can simple ways provide more inspiration?

To try to answer some of those questions I decided to do some tests with six of my favourite woods: Basswood, Oak, Cherry, Walnut, Mahogany and Birch plywood, as shown in the photo below. I then decided on four finishes: plain unsanded wood (A), Plasti-Kote aerosol clear-coat (B), Danish Oil (C) and Shellac sanding sealer (D). The last three were all done in two coats and after light sanding with 400 and 1000 grit sanding paper/pads. I think one of the most interesting things the photo shows is that all three surface finishes, even the simple spray-on clear-coat, enhanced colour and grain significantly.

Comparison images of the six woods before and after applying surface finishes

The unsanded woods (A) were obviously a little plain and dull, but still nice for many uses. The simple clear-coat (B), however, was much more interesting as it’s a very simple finishing process yet brought out the colour and grain structure very well. The main comment in comparison to the other finishes is that it gave a slightly darker look to the wood, although not in an unpleasant way. In comparison, I think the Danish Oil (C) gave a slightly nicer look to the grain, as well as bringing out the colour of the wood beautifully. Probably that’s due to it being mostly oil (see my post here) and so likely soaked deeper into the wood surface before hardening.

The sanding sealer (D) also gave a nice finish, although it was slightly duller. That’s not surprising though as its’ purpose is mostly to provide a sealed surface that can be lightly sanded smooth before applying other coatings. In the past I’ve used it with a finish of wax polish for a traditional look, and I think that would work well with the results here. The only other thing to note is, for me anyway, that the finishes improved the plain colours and grains of the Basswood and Birch plywood, even giving them some of the look of pine which could be useful for many projects. However, for a more exciting look they may benefit from a little wood stain/dye: in the case of the Danish Oil that can include darker oils that are commonly available.

Overall, I think the main conclusion from my tests is that simply applying a synthetic clear-coat to a carefully sanded wood surface is just as effective as more traditional techniques. Certainly it enhanced the colour and grain of all of the woods as well as giving an extra level of darkness if that’s what you want. Of course, using the other, more traditional, techniques gives subtly different effects so they still have a role to play and can be used with a final clear-coat too for some nice effects. Really it’s all down to our judgement, but without any need to feel guilty that using a cheap and simple clear-coat is cheating: in fact it’s a useful technique that compliments traditional finishes very nicely.

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Cutting gaskets from EVA foam with a diode-LASER

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.

A photo of the laser cut EVA foam gasket together with a photo of the limited damage to the underlying MDF sheet

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 🙂

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Spring loaded detail/finger sanders for finishing CNC projects

Sandpaper, as well as sanding blocks and detailing sponges, are essential for all CNC projects. They let us remove flaws, smooth surfaces and prepare materials for finishing with a variety of coatings. For many projects though, especially the small ones, they can be too big and bulky and can indiscriminately remove small, often fragile, details, as well as changing shaped edges away from what we so carefully designed.

So, for newcomers to CNC work, I thought I’d add this short post to quickly mention my experiences with spring-loaded detail/finger sanders. Mine is shown in the photo above and it’s simply a plastic finger with a continuous band of replaceable sandpaper around the outside. They come in many sizes, the one here being 20mm wide, although 10mm and 30mm ones are common. They also cost just a few pounds: try searching for something like ‘finger sander spring loaded’ on eBay or Amazon to see what I mean.

One of the most exciting things about finger sanders is the variety of sanding points. To start with there’s a long flat zone at the bottom, allowing sanding of large areas and straightening of cut edges. There’s also a narrow area at the front which allows for getting the sandpaper into tight places and around curves. Plus the rest of it has compound curves that can be very useful too. And when the paper starts to get worn where you need it, just push the pointy front end inward to slacken the sandpaper so you can rotate it around the edge. Personally I find them very useful as you can see in my photo of a Darth Vader routing project below.

A detail finger sander with a walnut routed Darth Vader

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