Duet CNC Controller – Part 7 / LASER

Video | Posted on by spapasavva
  • 00:00 Intro
  • 00:17 Laser Head
  • 01:05 uSpot Lens
  • 01:22 Air Assist Nozzle
  • 01:55 Magnetic Docking Station
  • 02:31 CNC Adapter
  • 03:18 Wiring
  • 05:08 Programming CNC Adapter
  • 06:09 Only Complaint
  • 06:27 Wiring Diagram
  • 06:42 Duet Controller Settings
  • 08:35 Z Height Macro
  • 08:56 XY Tool Offset Macro
  • 10:34 Laser to Spindle Offset Test
  • 11:16 Conclusion

In the previous video I installed my tangential knife and laser adapter mount to the z axis of the Moot One desktop CNC machine – and in this video I will explain how I wired the laser to the Duet controller and the relevant workflow for its use.

So to start – this is the laser head which was sent to me by opt lasers (with an s) to use and review. They had previously sent me the older type back in 2017 but this is much newer version and contains a lot more functionality including safety features.

The body is the PLH3D-6W-XF+ with the optional uSpot upgrade. (£635.10)

Noticeable changes include an arming LED on the head to keep you aware of what is going on, plus upon digging around the thick user manual, the option to use 0-10v signal in with a simple pot switch.

The best-selling 6 W laser from PLH3D Series. Professional engraving laser designed for industrial applications. Features a robust design, compatibility with all types of control signals used in CNC and 3D printing market. It can be powered with a wide range of PSUs and boasts the most powerful fan for its size, providing outstanding cooling and smoke removal. It comes with a lens adjusting tool.

The µSpot Lens Upgrade allows you to reach up to 2.5 times higher laser cutting and engraving speed compared to the standard version of our new generation of PLH3D-6W-XF+ Laser Heads. Boosting laser cutting performance enables you to laser process a wider range of materials, particularly so in the case of textiles and films. It also simplifies reaching the lens for your lens cleaning routine.

The u-stop lens focuses the diode laser beam to a sharper point and is designed to increase the efficiency of the engraving/cutting process. Opt Lasers suggest up to 2.5 times higher speed compared to the standard version.

In addition to that this includes the High-Pressure Air Assist Nozzle Kit. (£109.49)

High-Pressure Air Assist Nozzle is an invaluable resource for cutting and engraving with a laser. Being able to increase the speed of laser cutting and engraving by up to 6.5 times compared to the base speed as well as substantially improve the quality of the processed objects makes it a perfect tool for anyone who wants to produce top-notch quality items with uniform and well-defined features.

I assume this is achieved by blasting any smoke away from the focal point and turning the focal spot into a mini blast furnace.

All this is installed onto the LaserDock Magnetic Docking Station. (£123.37)

This docking station is designed to allow PLH3D-6W–Series laser heads to quickly connect or disconnect from machines. Aids easy removal of the laser head when it is not in use. Protects the laser unit from oils, metal particles, and dust. Includes an Aluminium cover that shields the mechanical surfaces and electronic contacts which interface with the laser head.

Now all that is connected to the PLH3D-CNC Adapter which is inside my enclosure. (£86.87)

The PLH3D-CNC Adapter serves as a versatile interface and safety unit connected in between a CNC machine and a high-performance PLH3D laser head.

All together the total price is £954.83 which might seem like a lot, but the running costs of CO2 lasers can be several thousand pounds a year. This is visually and functionally a spectacularly made piece of kit – machined aluminium with wonderful details which make it feel like a part of the International Space Station.

Ok so to wiring this up – you will need a separate power supply from the rest of your controller and stepper electronics. This can be anything between 15 and 24v and I’m using a 24V 3.2A Mean Well PSU.

On my controller this goes to the DC power terminal on the adapter with the cable including a inline ferrite core.

The terminals on the left of the adapter are wired through the CNC trunking to the laser head – and include voltage in and ground which are at the top, followed by the signal ground, TTL and analogue 5v.

For additional safety, I’ve wired a key switch and my main e-stop to the terminals at the top left which breaks the power if opened. The key is left normally opened when the laser is not armed, while the emergency stop contact opens when pressed cutting power to the laser head.

On the right-hand side are the inputs from the controller.

There I have wired the PWM/TTL input (terminal 2) from the Duex.PWM5 header on the Duex5 board.  Below that is terminal 3, which is the Enable #1 input which has 5 volts coming in from the same Duex header however this time via a normally open relay module. I use the E5.heat terminal to switch the relay whenever I change to the laser tool within the duet web controller – in my case tool 0. Terminal 4 goes to the ground on the same Duex.PWM5 header.

This is a diagram of the duex board – and it is important to note here that the PWM/Servo channels are shared with the heater ones. As I’m using the PWM5 terminals I will not be using the E6 heater for anything else. There is also a red warning label at the bottom corner too.

Now you will have to programme your adapter for the particular enable input states – and this is done by switching the key off, pressing the red arming button, turning the key back to on and waiting a few seconds. Pressing the arming button toggles between these enable input states. I am using programme option 2 where enable 1 is high and enable 2 is any or ignored.

You may need to selected your head type as well – by doing the same start up procedure but waiting until the LED perform some kind of light run and show you these options. With options 0 if the head is armed and removed – returning the laser will allow it to power back up when returned, and option 2 will result in discontinuity and having the repress the red arming button.

Annoying and this is my only complaint – I must open my enclosure to arm the laser and the adapter should really have an extension for that button so the electronics can be kept isolated.

This is my wiring diagram for my setup which you can pause to have a look at. A clearer and more up to date version will be available to my patreons along with the relevant duet files while I’m still working on this.

Ok, I’ll now talk about the duet settings and it’s important to mention my cnc machine will have 4 tools. Tool 0 is the laser, tool 1 is the spindle router and main tool, tool 2 is a pen plotter attachment and tool 3 is a tangential knife.

This is the relevant part for the tools within the config.g file in the system folder and in case you were wondering, I am using the latest firmware version which his RRF3.3.0.

M453 sets the machine to CNC mode, while M950 defines to which pins will be used for the  spindle on and rpm. M563 P0 defines the tool name and number with laser assigned to tool 0, and you can see for P1 the spindle is assigned to that tool with R1. While P2 is the pen plotter and P3 the tang knife.

Additionally, I have also included another M950 command to define the pin which will trigger the relay module that sends the signal to the enable #1 input on the adapter and by default that is off.

No tool is selected within my config file as when I load a cutting job from my CAM software (v-carve desktop) I define the tool used by its database number. Within the system file each tool can have an associated tpre#.g file,  tfree.g file and tpost#.g. 

When I select tool 0, tpre0.g is called and I use an M452 command to select laser mode, defining the pin that will send the signal to the CNC adapter, the working range which is 255 and PWM frequency. I use the M42 command to switch enable #1 to high.

G10 L2 P2 sets the z height which is worked out from a separate setting up macro. So the tool body is 60mm away from the wasteboard. Within Tfree0.g I turn the enable #1 to low so the laser cannot be accidently turned on.

The X and Y axis offset between the fixed tool (0, 1 and 3) is worked out by yet another macro I wrote. Where I mark a cross on a sacrificial surface – the thickness of which I must manually add to the macro itself. After which I can jog tool 1 to the centre of the mark from tool 0, with a v bit in the collet saving the location to a spare work coordinate. I then remove the tool from that collet – place another v-bit into Tool 3 the tang knife collet, and jog to the same mark and save that to another work coordinate. The offsets are saved along the way to the tool number and are recalled whenever the tool is selected.

I’m now going to engrave a shape and laser into the engraving – to demonstrate the accuracy between the two tools. And as you can see it seems pretty good.

This setup might be useful for going between milling a cradle for an object to be held, and then to laser engrave onto it. And I’ve also thought about using the laser to spot solder components onto a PCB – not sure if that’s possible but again with this setup I could give it a shot quite easily.

So I think this video is over – please check out the links in the description and let me know if you have any comments or questions down below. I’m pretty much done with the controller build apart from possibly wiring up an air pump and solenoid valves, but I’m still thinking about that. As always thanks again for watching and to my patreons for their support and you’ll catch me in the next one.