Air assist on the k40 laser machine

K40 laser cutter air assist

This list is work in progress, suggest changes or addons to it in the comments.

This article will help you optimize your air flow settings for your machine.

What is air assist?

Air assist is the help of a air stream keeping the cut or engraving clean from debris and smoke.
The laser beam works similar to your headlights on the car, too much fog and the visibility goes down. Same with the laser, too much smoke or other obstacles the power will go down and the quality with it.

When should i use air assist?

When you are cutting?
Cutting through materials a air assist helps you keeping the cut clean.

When you are engraving?
The air assist just push the smoke back to the material, Here is a Smoke assist better to use, preventing the fumes destroying the work.

Usual misconception about air assist

On many groups and forums the air assist is the same as a nozzle, like this one.

This is not air assist, at all.
This is a nozzle to hold your lens with built in air assist, bad air assist too.

This is why air assist nozzles literally sucks

Some chinese manufacturer thought it was a good idea to add theese nozzles to our smaller 40 watt machines, they looked at the big boys industry lasers and noticed the nozzle, without understanding why they had a nozzle.
The bad things
– You need higher airflow and pressure
– Big, noisy and often expensive compressor needed
– The air goes all over, not a nice small stream but a jet shooting all over.
– The venturi effect makes the nozzle a vacuum cleaner, pulling smoke in above and makes your lens dirtier, quicker.
– You have to spend alot of time just to change your lens, or clean it.

The nozzle is not a bad idea, but the way the chinese make them is really bad.
A good nozzle should be maximum 5mm from the surface, not 30-40mm letting the air go all over due to the cone shape.

This is why we have nozzles on the K40´s.
What theese nozzles are made for, on industry lasers, is to add gas mixes to the beam to help the cutting performance on steel and other metals.
You should under no circumstances add any type of gas to the K40.
This bad design idea has grown out of proportions and should not be used, at all.

How you hook up good working air assist

Add a 4-6mm air hose to a compressor, can be anything from a small fish tank airator to a 50L/min small pump.
If you want to cut wood or do a lot of engraving, a bit more flow is needed.
On the end of the hose, add a metal or plastic pipe you can bend. (i use 4mm brake lines).
Aim the pipe to where the cut hits.
This solution has more airflow in a single jet than the nozzles can produce with the same pump.

Picture of my air assist

Why this works

Try this, put your hand 5″ in front of your mouth – blow
Now try the same thing with a straw, blow the same you did before.
The laser beam is about 0.2mm thick, wich type of blow do you think is most effective? 😉

Using a small fish tank air pump you can get away with  $20 for pump, hose and connectors needed. And when the pump is running the sound level isn´t higher than your computer.

I hear all the time “i have a nozzle, it works, you are wrong”, yes it works, but you spent money on it, and you have a pump you spent money on, or using a big shop air compressor.
You can have the same effect with a nozzle as with a small pump, it just demands much more flow, pressure and aiming to do the same job.
With nozzle – more pressure, flow, bigger pump, more noise, less effective, more problems cleaning lens, dirtier lens more often.
The negative parts in the nozzle solution is why i tell people not do buy one, not because it “doesn´t work”, because it does work, but comes with a bag of negative features.

If you already have a nozzle, use it. But don´t buy one if you do not have one before you tried my solution 😉

The only air assist nozzle i approve
Since this article was written i have been busy testing a bunch of air assist laser head combos, and found one that actually works.

This laser head is not perfect, but can be modded to perfection. With a movable neck you can set the proper height and focus of your machine with the twist of your hand.
Easy to set proper focus, good protection for the lens and a fairly good mirror holder.
Can be found in my store here.

Using a air assist nozzle can have good results when engraving wood, i would rather suggest you optimize a smoke assist system in your machine than buying a nozzle.

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