A brief overview of the K40 Laser Cutter
The K40 laser cutter is a cheap, Chinese made 40 watt CO2 laser engraver and cutter. Typically, you will see them on places like ebay in a pale sky blue and light grey. They have some significant positives but a number of negatives as well:
- Low cost
- Easily upgradable
- The basic software supplied with the unit is awful
- Software requires a dongle
- Poor fume extraction
- Default work area is too small
- No air assist
And I am not going to mention safety as I have already 'laser’ed my thumb once.
I’ll will come back to the software as there is an easy fix for this one.Firstly lets address the hardware issues:
1. Default work area is too small:
This is the standard ‘out of the box’ setup for the workarea on a K40:
The large silver bordered hole in the bed is the clamp for the material you are working on. As you can see it is pretty small. The first thing I did was remove the clamp and put a piece of steel, cut to size, in the hole. This worked great and increased my bed. The next thing I did was cut the fume extractor back. This may seem mad when fume extraction is another issue but that issue is to do with the extraction fan, not the extractor tube in the unit. Finally I found a piece of clear vinyl tube on the forwards/backwards rail that limited the movement of the head at the front of the machine (no stop switches so you can over drive it). I removed about 25mm from this stop so I could get the laser cutter head as far forward as possible. This increased my available cutting area to 230mm x 340mm. Not a bad cutting area. My final modification the bed was to lower the whole bed by 12.5 mm and add some aluminium standoff. This improves the underside of the material as it is cut, a solid metal bed reflects the laser and adds burns to the underside of the material. So my cutting bed now looks like this (admittedly in need of a clean and yes the extractor was cut with my dremmel and needs cleaning up ).
2. Poor fume extraction
The poor fume extraction is due to a huge, poor quality fan that doesn’t fit:
My next upgrade will be to replace this fan with a sealed plate on the back of the unit, that actually fits and then connect this via a tube to a higher quality extractor unit.
3. No Air Assist
Air assist is when you pump compressed air over the cutting point as the laser cuts. It helps in two areas:
- It stops the smoke hanging around a getting in the way of the laser - so you get better cuts and your optics need less cleaning.
- It reduces the risk of fire. If you cut plywood you will often see flames (which is scary) but with air assist no flames and a cleaner cut.
So I added Air Assist with a 3d printed nozzle and a piston compressor from an airbrush painting rig. There are lots of variants of air assist nozzles on thingiverse but I went with this one in the end: https://www.thingiverse.com/thing:1189368 and it works very well on my setup. Just a length of silicon tube to connect it to the compressor.