Adding a shield to a CNC-mounted LASER module

My LASER is an attachment for my cheap Chinese 1610 CNC router so it isn’t tucked away inside a metal case with a tinted window. That means I have to wear LASER-safety glasses whenever it’s running, which can be annoying if I’ve got other things to do. So I designed this simple 3D printed shield with dark red windows (as the LASER is blue). It comprises a small frame that slips onto the LASER module (with a hole for a screw if needed to stop it sliding down) and a three-sided shield that slides onto the edge of the frame, as shown below.

3D view of the laser shield assembly

After 3D printing the front and two sides need to have dark red plastic glued in: I cut mine from a plastic square photography filter I picked up cheap on eBay. Then those three pieces need gluing together at the front corners to make the shield. If you want to add some rigidity then there’s also a bottom component you can stick below the three sides. The shield is then easily removed for when you want to focus the LASER or for removing cut materials. You can download the 3D printing files from Thingiverse by clicking here, and in case you need to make adjustments that includes the OpenSCAD file. The shield also works well with my LASER extractor project, localising the area it extracts air from, which is one reason why the bottom plate is included in the design.

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Mounting a GoPro camera on a CNC machine

Sometimes it’s nice to make a video, even a timelapse one, of a project coming to fruition on a CNC machine. Maybe just as a keepsake, or to share, or even to make some educational Maker instructions. So being able to add a GoPro camera, or other camera that uses GoPro mounts, is something you may want. I did anyway, so the project shown above is a simple 3D printed mount that clips onto a 20mm-extrusion on the front frame of my CNC, which can be positioned right in-line with the work-bed centre.

It’s a very simple 3D printing project that doesn’t even need any support material, so shouldn’t be a challenge if you have access to a 3D printer. The files you can download from Thingiverse by clicking here, which include the OpenSCAD file in case you need to customise or adjust it. Once made you use it to fix on a sticky mount base like in the photo, for your camera arm to fit onto. And below is a photo of my GoPro session mounted on my CNC so you can get a better idea of how it works.

A GoPro camera mounted to a CNC frame

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Add Bluetooth to make your CNC wireless

Most cheap CNC machines come with a GRBL controller board that communicates with a computer using a wired USB connection. There’s no problem with that if you want a computer near your CNC, but a much more convenient way to communicate with it is over a wireless connection. That way you can keep your valuable PC well away from potential hazards or even use an Android tablet or smartphone instead. And the easiest way to do that is add a Bluetooth module to the GRBL board if it has serial connections available.

So a bit of manual reading, and looking at the boards’ circuit diagram, are necessary. You’ll be looking for connections for connecting wires to its positive (e.g. 3.3V or 5V) and negative (a.k.a. ground or earth), transmit (Tx) and receive (Rx) headers. Normally they’ll be on pins soldered into the board. Then you need a Bluetooth-serial module which are a few pounds/dollars on eBay or Amazon: I used a HC-05 which is commonly available. The module will need its name and communications speed set up first and I’ve put some tips on that at the bottom of this post.

Then the Bluetooth module needs a connection from positive to Vcc and from ground to GND, to power it. The Tx on the GRBL board goes to Rx on the Bluetooth module and, similarly, Rx goes to Tx. I’ve put a diagram below that shows how I wired my HC-05 to my Woodpecker 3.1 GRBL controller board, which is quite common on cheap Chinese CNC machines. Sometimes Tx and Rx connections are reversed on the Bluetooth modules, so if you have problems you can try swapping them over. And to make it easy to get started consider using female-female jumper wires (i.e. sockets both ends) for the connections, like I used in the photo above, before committing yourself.

Circuit diagram for an example Bluetooth wireless connection
Hopefully now your Bluetooth module will flash an LED when the CNC is powered, to tell you it’s waiting for a connection. If not, check everything carefully, especially your positive and ground wiring. If that’s OK you should be ready to pair with your PC or Android device and have fun doing wireless CNC’ing.

Setting up a HC-05 Bluetooth module with an Arduino

If you know nothing about microcontrollers then now is probably a good time to find a friend who does, or even try to talk an online supplier into doing the setup when you buy. However, it isn’t really very difficult if you have an Arduino as you just need to wire the HC-05 to it as described for the GRBL board above (see www.arduino.cc for help on your particular board). The code below can then be used to set the Bluetooth module to be called ‘CNC’ (which you can change) with a speed of 115200 bits/second. Most modern GRBL boards communicate at that speed but if yours is quite old, and uses 9600 bits/second, you can change ‘BAUD8’ to ‘BAUD4’ or simply remove that line. And then, hopefully, your HC-05 module is good to go.

void setup()
{
  Serial.begin(9600);
  delay(1000);
  Serial.print("AT+NAMECNC");
  delay(1000);
  Serial.print("AT+BAUD8");
}

void loop(){}

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Improving lead-screw binding with a flexible coupler

CNC machines have plenty of moving parts and if we want our routing and LASER cutting to be as good as possible the movements need to be as smooth and unrestricted as possible. When I built my cheap Chinese CNC it came with rigid shaft couplers for connecting the threaded lead screws to the stepper motors. That meant that the motor spindle and lead screw couldn’t be adjusted to be perfectly in-line, just because of tolerances in parts and mountings. So, for part of a full rotation the lead-screw was binding (i.e. becoming hard to turn) and the rest of the turn was fine.

If you find you get the same problem, you could just do what I did: change the rigid couplers for slightly flexible ones. In the photo below I’ve shown the difference between the two. The bottom one is the original rigid one and changing to the new one involved no more than loosening the grub-screws, moving the lead-screw to the side, then inserting the new coupler, pushing in the end of the lead-screw, and tightening the grub-screws. For just a few minutes work it made X and Y axis motions so much smoother. And, for only a few pounds/dollars per coupler it was a cheap job too.

A flexible and rigid coupler

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