Equipment/K40 Laser Cutter

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K40 Laser Cutter
3020 Laser.jpg
Model K40 Laser Cutter
Sub-category CNC
Status Working
Accessories Air-assist, extractor fan and water cooling system
Owner York Hackspace
Origin Purchased
Last updated 8 May 2019 10:53:13
Last updated by Choffee

The laser cutter was purchased 2nd hand by the space in late August 2017. We are still working out the capabilities/limitations and training for this machine, so please consider the below a work in progress. :)


  • Cutting area (W × D) : 300mm x 220mm (usable cutting area TBD)
  • Supported Materials: Laser-ply, acrylic, and others TBD


  • Physical Dimensions
  • Power Supply: 220 VAC, C13

How to use the Laser Cutter

  • Step 1. Don't look at the laser!
  • Step 2. Contact someone to ask for training: please don't use the cutter without training.

It's easy to break the laser cutter, yourself or the space if you don't know what you are doing. The instructions below are for reference only, and a paper copy can be found in the vicinity of the cutter.


The control panel on the laser looks like this:

laser cutter controls
Control Panel


  • Before starting, make sure the laser switch is off (the red cover is closed), the emergency switch is off (pushed down) and the laser current is at 0 (beyond "Off")
  • Open the window and put the extraction hose outside
  • Switch on the extension cord at the socket
  • You should be able to hear the air assist pump and extract fans. You might find the air assist pump is unplugged.
  • Check for water flow in the laser (rear hatch); the new cooling pump is very quiet. It's crucial that the water cooling is running at all times: firing the laser without it will fry the laser tube!
  • Turn on the emergency switch using the key. The laser cutting head should move slightly
  • Set the laser current to the correct setting
  • Arm the laser (red missile switch) and use the test button if needed before cutting

Note: If the water temperature goes above 25C please wait till it cools down again before starting a cut. If it goes above 27C Stop your cut as more than this can damage the laser tube.

Note: if you find the water cooling is not running while the laser is on, immediately disarm the laser and do not start the cooling system - the thermal shock may crack the tube


  • Disarm the laser (red missile switch)
  • Set the laser current to 0
  • Push down on the emergency stop switch
  • Leave the water cooling running after cutting, especially if you have been cutting for a while
  • Turn off the extension lead
  • Pull the extractor inside and shut the window
  • Tidy up and sign the record sheet on top of the cutter


You can use K40 Whisperer to control the laser cutter over USB from a windows or linux computer. Most of us design using Inkscape. The laptop in the drawer already has this installed and configured (it just takes an age to boot).


running K40 Whisperer on Ubuntu (and similar linux distros)

To run k40 on a linux machine:

Note: commands shown work in bash, you may need to adjust them for your shell

  • Download the source from here (take the latest version ending in
  • unzip to a folder anywhere on your computer
  • Install the python dependencies
    • one of these is a package in apt: sudo apt install python-tk
    • the others can be installed with pip, from the directory where you extracted k40: pip install -r requirements.txt (if you want to you can do this in a venv to avoid installing these packages globally, make sure it's a python2 venv if you do this)
    • Alternatively, instead of using pip you could install the apt packages that wrap the python packages (the names of these are usually "python-" followed by the name as shown on each line of requirements.txt) but I prefer the pip approach usually.
  • You should now be able to run k40 whisperer with python but clicking "initialise laser cutter" will likely result in an error
  • To enable k40 whisperer to talk to the cutter, you need to add a udev rule...
  • Create a file called /etc/udev/rules.d/99-k40.rules (you probably need to be root to do this) which contains the following text:

SUBSYSTEM=="usb", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="5512", ENV{DEVTYPE}=="usb_device", MODE="0664", GROUP="laser"

  • then create a group on your system called "laser" sudo addgroup laser
  • add yourself to the laser group, to give yourself permission to use the laser cutter USB device sudo adduser $(whoami) laser
  • restart udev, to apply the new rule sudo systemctl restart udev.service
  • plug in the laser cutter (if it's already plugged in, unplug it first)
  • start k40_whisperer again python, and you should find that the "initialise laser cutter" button works now.

Maybe some day a better version of k40 will be packaged in debian and ubuntu, then apt-installing it would do all this for you :D

Won't switch on

  • Is the emergency switch unlocked?
  • Check the plugs
  • Check fuses in the IEC cord and the back of the cutter

Laser doesn't fire

  • Check the laser current settings: it needs to be >5 to fire.
  • check if the laser will fire at all using the test button
  • Check the lid switches and the connections on the control panel


Here are some useful starting points for different materials. Note that old settings are shown here, unless explicitly stated that they have been updated since the new tube was installed.

Kitronics has a good hints and tips for lastercutting article.

Material Settings
Type Thickness Notes Mode Passes Current (mA) Speed (mm/s)
Laser Ply 3mm This is what the space stocks ( Well Tested)

As at 2019-04-19, after the tube was replaced, and the mirrors and lenses cleaned and aligned. Note the lower current for raster engraving.

Raster engrave 1 3 150
Vector engrave 1 5 40
Vector cut 2 5 10
Paper and Card Card Thin Card

Vector cut thin 7.5 30
Acrylic 2mm Updated after 2019-04-19, after the tube was replaced. Very thin sample from Raster settings here should work for any thickness acrylic. Vector cut 1 5 7
Raster engrave 1 5 300
3mm This is the standard Hackspace stock (Well Tested) Vector cut 2 5 6

A sample from

This is probably the largest thickness that still cuts fine. (Untested but you might need more passes, or slower)

Vector cut 3 5 6

This is the really thick stuff Nat bought. The regular acrylic is 3mm.

A little too thick for our cutter. Pieces need some massaging to remove, and may not do so cleanly. ( Untested)

Vector cut 3 5 6