Air assist

The DC-K40III is sold as a "laser engraver".

But, I want to use the machine as a laser cutter. It's more than capable of this.

Out of the box, I tried to cut paper and wood. Unless I was very lucky, the edges would begin smouldering or even catch fire.

To stop materials from burning, laser cutters need "air assist", a stream of air directed at the cut to blow out any flames and cool the material.

I rigged up a simple system using an electric car tyre pump from Halfords, some PVC tubing and cable ties.

Using this system, I get fairly good cuts without smouldering or flames. This is a small box cut from 3mm plywood.

MicroLoom

MicroLoom is a tiny loom I designed for weaving a patch of fabric.It would make a nice gift for a crafter. My kids enjoyed playing with it. There's the frame, a needle and a comb to help compact the threads after each line of weaving.

The design files are on Thingiverse http://www.thingiverse.com/thing:123412

MicroLoom can be cut from wood or acrylic (I used 3mm). I found that acrylic is much stronger, letting me put the frame under more tension.

More pictures on flickr.

Unboxing

For anyone considering buying a DC-K40III laser cutter, this is what you get in the box.

When the cutter arrived, it was well packed.

The laser tube had some padding inside the case. After removing, it was all in good condition.

 

The laser head was tied securely in place.

 

Supplied with the machine was an extractor fan and tube, US to UK mains adapters, water pump, software and dongle.

The front panel has a potentiometer to set the laser power. When it fires, the meter reflects the pot.

The controller board is for Moshidraw.

The laser power supply (the laser is enabled through an optocoupler at the bottom right of the picture)

The motors and controller board are powered from a 24V PSU.

A fool and his money

My laser cutter is a DC-K40III. It's a budget Chinese machine available on eBay.

I chose the machine for its low cost, it's half the price of any other new laser in the UK of similar spec.

Owning one of these is not for everyone:

• It is missing important safety features
• No lock on the lid to prevent opening the lid while running
• No lid switch to cutoff the laser when the protective lid is lifted
• The front panel is likely not earthed properly
• No temperature sensor/cutoff for water coolant reservoir
• Poor/non-existent seals in the casing (fire risk, smell of burning materials)
• The control hardware and PC software are locked to a USB dongle
• Both of the limit switches misfire causing the machine to grind
• X is a microswitch with a loose arm
• Y is an IR beam sensor which is poorly aligned
• The PC software is Windows XP only
• The PC software (and/or control hardware) cannot cope with complex designs and will randomly skip entire paths

However:

• It is mechanically good
• It is optically good
• It's hackable - it's just a CNC bed with a PWMable death-ray! What Could Possibly Go Wrong?
• I'm not dead/blind yet

I've owned the machine for about 9 months. Today, it works well enough for everyday use.

I have spent less money than buying a better laser cutter. But, it's still not as good and it's taken a lot time to get to this point. If you want a general purpose laser cutter for hobby or home use and have no interest in fiddling with it - do not buy a DC-K40III.

That said, I can't resist a bargain and I like a challenge.

I've run with the original control hardware, attempted (and ultimately failed) to replace it with an OSHW board. Currently, I'm using it with a "drop-in" semi-open control board - giving me a limited feature set, but good reliability.

I've added air assist (compressed air at the cutting point), joystick control and a laser crosshair for calibration.

This blog will record some my my experiences and projects with the laser.