The K40 Laser Engraver is a low-budget 30-Watt CNC laser, upgradeable to 40 Watts.

It is capable of engraving/cutting wood, acrylic, and other non-metals of thickness up to 1/4".  It will not cut or engrave most metals.

Image result for k40 laser cutter


Build Volume: Approximately 8"x12", currently with fixed Z-height

Modifications: Removed air suction port/slit to make more room for materials as well as better exhaust; Upgraded air suction system with two additional bilge-blower fans (1 mounted on laser rear and 1 mounted on wall exhaust port); added optional rotary tool attachment; Added air-assist nozzle with 18mm lens (air assist is critical for wood due to flare-ups); added flow indicator to coolant line for easy visual check that water pump is working

General Procedures

Laser engravers/cutters are cool tools.  They can also be extremely dangerous and highly hazardous.  There are certain things you should NEVER do with a laser engraver/cutter in a community space (and in general).  Be advised that these prohibited activities have the potential to cause physical harm to our members.  If you do these things, you will at a minimum be restricted from using our laser.  

  • Cutting hazardous/unapproved materials.
    • You MUST consult the Approved Materials List (and the Never Use List) - see below - before cutting.
  • Leaving the laser unattended.
    • You must monitor the laser at all times for the duration that you are using it.  Someone needs to be able to safely shut down the machine and mitigate a potential hazard if unexpected behavior occurs.
  • Opening the laser door while the tool is in operation.
    • This is an incredibly bad thing to do, as this laser has the potential to cause permanent blindness, amongst other things.  There is no reason to do this while the machine is in operation.


  1. Turn on the laser using the power strip it is connected to.  This will also turn on the inline blower fan, water pump and compressor.
  2. Verify that the water pump is functioning by checking the flow indicator on the coolant bucket.  It should be spinning.  If it is not functioning, do not use the laser, and report this immediately.
  3. From the CAD computer, open K40 Whisperer, and load your SVG file.
  4. If the laser axis is not homed, click "Initialize Laser", then click the home button in K40 Whisperer.
  5. Verify that the Current Dial is set to the appropriate setting for your activity on the laser.
  6. Verify that the momentary button/switch to activate the laser is enabled (should be pressed in).
  7. Specify whether you are cutting or engraving in K40 Whisperer, as well as your speed, and click the associated button to start the laser.
  9. If the laser behaves unexpectedly or a hazardous incident occurs, turn the laser off by flipping the large orange switch on the top of the laser.  Do not turn off the power strip, as this will turn off the fume extraction.  If you are unsure what happened, contact an authorized trainer.
  10. When your job is complete, wait at least 60 seconds for excess fumes to be extracted, then open the laser door and remove your piece.
  11. Shut off the laser by turning off the power strip.

Approved Laser Material List

Material Max thickness Notes WARNINGS!
Many woods 1/4" Avoid oily/resinous woods Be very careful about cutting oily woods, or very resinous woods as they also may catch fire.
Plywood/Composite woods 1/4" These contain glue, and may not laser cut as well as solid wood.
MDF/Engineered woods 1/4" These are okay to use but may experience a higher amount of charring when cut.
Paper, card stock thin Cuts very well on the laser cutter, and also very quickly.
Cardboard, carton thicker Cuts well but may catch fire. Watch for fire.
Cork 1/8" Thin cork can be cut, but the quality of the cut depends on the thickness and quality of the cork. Engineered cork has a lot of glue in it, and may not cut as well. Avoid cutting thicker cork (5mm). Engraves well, cuts poorly.
Acrylic/Lucite/Plexiglas/PMMA 1/2" Cuts extremely well leaving a beautifully polished edge.
Thin Polycarbonate Sheeting (<1mm) <1mm Very thin polycarbonate can be cut, but tends to discolor badly. Extremely thin sheets (0.5mm and less) may cut with yellowed/discolored edges. Polycarbonate absorbs IR strongly, and is a poor material to use in the laser cutter. Watch for smoking/burning
Delrin (POM) thin Delrin comes in a number of shore strengths (hardness) and the harder Delrin tends to work better. Great for gears!
Kapton tape (Polyimide) 1/16" Works well, in thin sheets and strips like tape.
Mylar 1/16" Works well if it's thin. Thick mylar has a tendency to warp, bubble, and curl Gold coated mylar will not work.
Solid Styrene 1/16" Smokes a lot when cut, but can be cut. Keep it thin.
Depron foam 1/4" Used a lot for hobby, RC aircraft, architectural models, and toys. 1/4" cuts nicely, with a smooth edge. Must be constantly monitored.
Gator foam Foam core gets burned and eaten away compared to the top and bottom hard paper shell. Not a fantastic thing to cut, but it can be cut if watched.
Cloth/felt/hemp/cotton They all cut well. Our lasers can be used in lace-making. Not plastic coated or impregnated cloth!
Leather/Suede 1/8" Leather is very hard to cut, but can be if it's thinner than a belt (call it 1/8"). Our "Advanced" laser training class covers this. Real leather only! Not 'pleather' or other imitations .. they are made of PVC.
Magnetic Sheet Cuts beautifully
NON-CHLORINE-containing rubber Fine for cutting. Beware chlorine-containing rubber!
Teflon (PTFE) thin Cuts OK in thin sheets. See https://www.ulsinc.com/materials/teflon ; the issues listed in https://en.wikipedia.org/wiki/Polymer_fume_fever should not matter because our lasers are fully vented and exhausted.
Carbon fiber mats/weave
that has not had epoxy applied
Can be cut, very slowly. You must not cut carbon fiber that has been coated!!
Coroplast ('corrugated plastic') 1/4" Difficult because of the vertical strips. Three passes at 80% power, 7% speed, and it will be slightly connected still at the bottom from the vertical strips.


Material DANGER! Cause/Consequence
PVC (Poly Vinyl Chloride)/vinyl/pleather/artificial leather Emits chlorine gas when cut! Don't ever cut this material as it will ruin the optics, causes the metal of the machine to corrode as chlorine is released and ruins the motion control system.
Thick ( >1mm ) Polycarbonate/Lexan Cuts very poorly, discolors, catches fire Polycarbonate is often found as flat, sheet material. The window of the laser cutter is made of Polycarbonate because polycarbonate strongly absorbs infrared radiation! This is the frequency of light the laser cutter uses to cut materials, so it is very ineffective at cutting polycarbonate. Polycarbonate is a poor choice for laser cutting. It creates long stringy clouds of soot that float up, ruin the optics and mess up the machine.
ABS Melts / Cyanide ABS does not cut well in a laser cutter. It tends to melt rather than vaporize, and has a higher chance of catching on fire and leaving behind melted gooey deposits on the vector cutting grid. It also does not engrave well (again, tends to melt). Cutting ABS plastic emits hydrogen cyanide, which is unsafe at any concentration.
HDPE/milk bottle plastic Catches fire and melts It melts. It gets gooey. It catches fire. Don't use it.
PolyStyrene Foam Catches fire It catches fire quickly, burns rapidly, it melts, and only thin pieces cut. This is the #1 material that causes laser fires!!!
PolyPropylene Foam Catches fire Like PolyStyrene, it melts, catches fire, and the melted drops continue to burn and turn into rock-hard drips and pebbles.
Epoxy burn / smoke Epoxy is an aliphatic resin, strongly cross-linked carbon chains. A CO2 laser can't cut it, and the resulting burned mess creates toxic fumes ( like cyanide! ). Items coated in Epoxy, or cast Epoxy resins must not be used in the laser cutter. ( see Fiberglass )
Fiberglass Emits fumes It's a mix of two materials that cant' be cut. Glass (etch, no cut) and epoxy resin (fumes)
Coated Carbon Fiber Emits noxious fumes A mix of two materials. Thin carbon fiber mat can be cut, with some fraying - but not when coated.
Any foodstuff ( such as meat, seaweed 'nori' sheets, cookie dough, bread, tortillas... ) The laser is not designed to cut food, and people cut things that create poisonous/noxious substances such as wood smoke and acrylic smoke. If you want to cut foodstuffs, consider sponsoring a food-only laser cutter for the space that is kept as clean as a commercial kitchen would require.
Material with Sticky Glue Backing Coats lens, cracks lens There are many normally laserable items such as thin wood laminates that you can purchase that become un-cuttable when the manufacturer adds a layer of peel-off glue on the bottom to attach them to surfaces. Examples include cork tiles, thin wood laminate, acrylic tiles, and paper stickers. Never cut these materials in the laser cutter if they have this backing. The glue will vaporize forming a coating on the lens that will coat it, cloud it, heat it, and then potentially crack the lens. The glue residue is worse than resin, and can't be removed without risking damage to the lens ... requiring a lens replacement.



Hazards & Safety


Moving Parts. Many of our tools have rotating parts, gears, belts, blades, pulleys, gantries, etc.  You should always make sure you have secured loose hair/clothing/accessories at all times.  Additionally, do not wear any kind of gloves when using mechanical equipment, due to snagging risks.

 Hazardous Lasers/Light in use.  Always view light through a UV barrier or with UV eye protection (such as a welding hood or UV goggles)

Roswell FireLabs
1601 Holcomb Bridge Rd

Roswell, GA 30076

Roswell FireLabs is managed by Atlanta Maker Alliance, Inc., a local 501(c)3 non-profit organization.

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