K40 Laser Cutter (depreciated)

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This version of the laser cutter has been moved away for a while. For the latest see Laser Cutter. But the article shall be left here in case of it's return (along with Tim) and any legacy information needed.


Do not leave the laser unattended when on. Do not leave material on the laser bed

Please do not cut above 85% power (18ma) as this will accelerate the deterioration of the tube.

K40 Laser Cutter

ing settings On Loan from tim_n until Nov 2018 (end of contract)

The K40 Laser Cutter


Currently online for cutting and engraving. Only use if you've been inducted.

News for 2018!

Liquid cooling coolness! No more manky buckets! 50w tube (as opposed to 20w) gives moAr power! unstable power supply whose coil is likely to blow any day now!

Coming soon!

powered z-bed circular engraving for bottles/jars/very short rolling pins etc


The K40 Laser cutter has been updated to run off a smoothieware Cohesion 3D board. Interface runs off Laserweb 4.0

Rules for use

Rule 0. Do not be on fire.

  1. If you're not sure, don't do it (even switch it on)
  2. Do not leave the laser cutter running unattended for any reason. See Hackspace Rule 0
  3. Donations accepted - £5 per hour of cutting appreciated for replacement tube. There's a lasercut ply honesty box on the shelf above the cutter.
  4. Log job settings/length of print run below (please time it) as this helps understand how much life we're getting out of the tube.
  5. Follow the procedure for use below.
  6. Only Materials approved for laser use can be used. If in doubt, don't cut it.

Laser Alignment

In the case of the K40 requiring alignment, please let Tim_n or James know and dont do it yourself. There are various safeties that need circumventing to do it now and we'd rather they weren't tampered with.

If you want to see how it's done:

Aligning a small bed laser is fairly easy, it just takes time and patience. As a laser only works in 2D, you only have the X and Y axis to align.

The most typical place for it to be out of alignment is bottom right corner of the cutting bed. If you find it cutting top left and not cutting bottom right, it's probably out of alignment. Any large knock or bash may push the laser out of alignment.

Do not attempt to align the laser with the lid open unless you've got some sort of goggles on and no-one else is in visual range. A reflected beam does not do your eyes any good. Mild charring may occur if you stick your hand in the beam before the lens (it feels holding your hand over a very hot lighter. Don't ask how I know this, it's a rule 0 violation)

There's a lot of places that talk about laser alignment:

Laser alignment by Nycon

K40 Laser Alignment by Richard

Make sure before making adjustments you loosen the nuts on the y axis mirror (and carefully tighten them after alignment and retest after you do!). Do not adjust the one inside the laser housing at the back of the laser. Make sure the laser is on low power so you don't smoke the mirrors.

Procedure for use

Note: This laser cutter used in the wrong way can cause some wonderful injuries and fires. Please don't use this unless you've had a brief from a maintainer.

Power on cycle

The main power for the laser and associated items are all powered off the 6 gang.

Check that the following is plugged in before switch on.

Both black plugs from the laser Fan Air assist

Look at the pump for the air bubble that sits just before the fluid reservoir is present.

Turn on the 6 gang at the wall, then the switch on the 6 gang. Ensure the pump is running (bubble above fluid reservoir should disappear into the tank and it'll be vaguely vibrating.

Switch on the main ventilation fan on the wall and make sure the vent diverter is set to on.

Check the main fan is running behind the laser.

Check air assist is on and attached to the laser head.

Switch on the main laser control panel.

Connect USB lead to computer and load Laserweb

Click connection tab, click connect.

The emergency off switch should be depressed. Rotate this to enable it. Laser still not working? You've probably not been trained and don't know the final secret I'm not posting on the wiki!


Power off cycle

Finished? All in reverse.

Press the emergency stop button(s) On the connection tab hit disconnect Unplug USB. Switch off the main laser pnel Turn off the air assist, main fan, main ventilation system and return the blue switch to the closed position. Turn off the 6 gang, then off at the wall.

Everything should be quiet. Unless it's noisy in the space anyway.


We're using LaserWeb 4, which is installed on the laser PC, and drives it directly via USB. LaserWeb 4 can import various file formats, including SVG for vectors and PNG/JPEG for rasters.

In SVGs, make sure you convert any text to paths (Inkscape can do this, via the menu: Object -> Object to Path). This creates a vector file. If you have an image in inkscape and you convert to path, it will go from a raster to a vector, so no fill in.

Idiots guide to Laserweb 4

  • Ensure laser is on and connected via USB
  • Load Laserweb4 using icon off the desktop
  • click on the connection tab, select "connect"
  • check you get a green "machine connected" in bottom right hand corner
  • click on control, press home button, wait till machine has homed and select the "set zero" option
  • goto "files" section
  • import your SVG/Raster. Make sure it's in the bottom right quadrant - ie the 0-300 X range and -0 to -200 (this is important)
  • select the layers or image you want to cut/raster
  • drag to the layers area beneath (into the drag and drop box) and set the settings.
  • You need to chose power range (0-100% on raster) and speed for the material and depth of cut. For a raster on ply for instance, 0-100% at 1,500m/s is probably fine...
  • Once all the relevant layers are coded, click the "generate" button. Check the g-code looks about right for what you're doing (ie it's not empty or only contains a couple of lines)
  • Go to control panel, press run. Stay with the laser until it's finished. Log your time, bung some money in the pot.

WATCH THE LASER WHILE IT GOES. Press emergency stop if anything goes bad. Co2 Fire extinguisher if it goes really, really, lifethreateningly bad. This is not good for the laser.

Cutting Settings

Here are some settings that have worked well:

Material Thickness  % of 18mA speed mm/min
Thin white card  ? 80% 2000
Acrylic / Perspex (black) 3mm 100% 200

Engraving Settings

Here are some settings that have worked well:

Material Engrave Depth  % of 18mA speed mm/min
Acrylic / Perspex (black) ~0.5mm 0-100% 1500
White Card ~0.3mm 0-15% 2500

Pre designed stuff!

Make project boxes Makercase

Thingiverse Thingiverse (yes they do laser stuff as well as 3d Printing stuff!)

Gears [1]

Timing gears [2]

Approved Materials


  • Laser rated Ply (not any old ply)
  • Laser rated MDF
  • Acrylic
  • Paper
  • Card/Cardboard
  • Laser safe rubber (stinks!)
  • Leather (stinks so do it during low useage times, think burning flesh...)
  • Felt


  • Laser safe Ply (not any old ply)
  • Laser safe MDF
  • Acrylic
  • Paper
  • Card/Cardboard
  • Laser safe rubber (stinks!)
  • Leather (stinks so do it during low useage times, think burning flesh...)
  • Some light coloured stone
  • Stainless Steel. Note, requires Dry Moly spray
  • Aluminimum. Note, requires Dry Moly spray
  • Ceramic. Note, requires Dry Moly spray

Where to get supplies/consumables/materials


Scraps box is good for small projects, it's free but donations welcomed.

3mm ply (measures under 3mm depth) is 50p a sheet. 4mm ply (measures under 4mm depth) is £1 a sheet.

The rest of the materials unless specifically marked are owned (probably by me) and I'd appreciate you not using them. We have some large sheets of acrylic you can purchase as well, I've just not cut/snapped it up yet.

Other places


An induction will cover:

  • How to turn on the laser without violating rule 0
  • Z-Bed alignment
  • What materials you can and can't cut
  • Cutting settings

Trouble shooting

Laser not firing?

  • Is everything turned on?
  • Is it on & on/off button lit?
  • Is the "arm" button pressed?
  • Is the emergency button down?
  • Did you set your layer power strength to higher than 1%

Things to do

  • fix & level z-axis leveling bed into place.
  • add cool LED lighting to inner case
  • float switch to disable use without pump being active
  • buy fire extinguisher to put nearby just in case of rule 0 violation
  • keyfob access to those who've been trained to use it.

* emergency switch to cut power to power supply * fix raster * add air assist head & by default new lens, * add z-axis driver * fix power control * replace arm/test switches as they have degraded This was a non issue fixed with sandpaper and a file. * contact switches to turn of laser if case opened * 9v supply to RAMPS board * better ventilation * new control panel with amp meter right way up * Watercooling system instead of pond pump & a bucket.

Buildlog details for those attempting their own

Circuit diagrams and how to blog by 3dprintzothar

Weistek Engineering Blog

Instructable by Downunder35

Google Groups Technical Support


On cheap RAMPS 1.4 board sets, the A4988 pololu copy hardware stepper drivers do not support 1/16 and jumper pins MS3 DO NOT WORK. Instead blank MS1 and MS2 to support 1/8 steps. Default steps per mm in the firmware then apply. Trying to set 1/16 on fake pololu drivers is impossible as it ignores MS3 - meaning you get full steps. Hope this helps someone...

Firmware - MK4Duo



Ensure you enable laser beam by uncommenting the line.

 #define LASER




 #define LASER_CONTROL 2

Pin out on our model are as follows:

 #define LASER_PWR_PIN                   5
 #define LASER_TTL_PIN                   6


Set both:

  1. define INVERT_X_DIR true
  2. define INVERT_Y_DIR true


  1. define X_MAX_POS 300
  2. define X_MIN_POS 0
  3. define Y_MAX_POS 200
  4. define Y_MIN_POS 0
  5. define Z_MAX_POS 50
  1. define DISABLE_E true (we don't have an extruder on a laser...)

5/1/17: Latest MK4Duo firmware has fixed the PWM control issue we had (no idea if it was a bug or software settings) but we're now getting full power control now that the manual PWM POT has been disconnected.

Will cut a new control panel to tidy everything up. Stepper settings still need tweaking to make it sound a little less grindy.

Additional hardware in use