It's here!

First thing I noticed when getting it out of the crate was the dent in the side. Although the crate itself looked fine, there was an obvious impact near the bottom on the right hand side. It wasn't too serious but did suggest that the machine had suffered a heavy hit or drop.

It arrived! Only 2 days delivery. My other half texted me to say I had an extremely large crate delivered. The cardboard crate was held together with huge staples and took a bit of work to get it open. Inside was a blue material pouch containing the software, cables, security dongle and manual and of course the machine wrapped in cellophane. The crate itself was thick walled honeycomb cardboard with a layer of polystyrene. I can see the crate protecting it from minor damage, but any heavy handing and I can see it denting or breaking the internal components.

Opening the machine revealed the extractor fan, the water pump and the extractor hose. The hose was a very cheap plastic one and it was crushed at various points. I then found bits of white plastic in the bottom of the machine. These came from the extractor fan. The fan was damaged at the point the cables went in, exposing the wiring.

I decided I could live with this damage so I installed the software an started setting up for a test. I connected the water pipes (which didn't in any way fit the pump supplied) and started pumping water around the laser tube system. I checked the laser tube had filled with water and plugged the whole thing in. I drew a simple circle in the LaserDraw software, dropped a sheet of MDF into the machine and hit "cut". The head moved in a cool little circle but with no laser cutting and a horrible shuddering noise.

I took out the wood and replaced it with paper and tried again. Same thing again. I moved the laser head into the centre of the machine and hit the laser "test" button. There was no hole. So I opened up the back of the machine and placed a piece of paper directly at the end of the laser tube, closed my eyes (I don't have goggles) and hit test for half a second. Nothing. Then for a second. Nothing. Then for 10 seconds! That's when I noticed that the laser tube didn't look right. Inside the tube there is a smaller tube running down the centre. This didn't quite look parallel with the main tube. On closer inspection I noticed a crack in the tube at one end with an obvious piece of glass missing.

I should have given in at this point, but I had the evening spare and I wanted to mess. Next I looked at the juddering. I noticed that the X gantry that holds the laser hear seemed not level. Not only that, the gantry wasn't at 90 degrees with the Y axis. Poking my camera phone in the gaps and taking photo's it was obvious that the top gantry was very un-level and the entire thing was at an angle. The top gantry was easy enough to fix. It just needed the end screws loosening and tightening back up while holding it level.

The skew on the whole thing needed one of the cogs that held the right hand belt loosening so that the right side of the gantry was able to move independently to the left. I moved it till it was parallel with the back of the machine and tightened it back up again.

To test it I taped a marker pen to the laser head and programmed in some shapes and letters. The pen was wobbling all over the place but it seemed to work well. The juddering was greatly reduced, although it still makes noises where it shouldn't.

I emailed the seller about all of the problems and requested a return. I packed it back in its crate and went to bed more than a little pissed off.

My Choice

After researching a bit I found there were several variations on the K40 that were being sold. The main variations that I cared about were

1) Analogue or Digital power setting
2) Air assist
3) Moshi-Draw / Laser-Draw / Corel-Laser
4) Location of device (UK or China)
5) Cost

1) The Analogue or Digital power setting is the method of setting the laser's power level. The laser can be adjusted from 0% (not firing at all), to 100% (40w of laser power). The Analogue version has a knob and a readout meter (misleadingly measures in milliamps). The Digital version has a set of buttons marked +/- 0.1%, 1% and 10%. The readout shows values from 00.0 to 99.9. They are essentially the same thing, but I wanted a digital readout for no real reason. I've since found out that there are real differences under the hood that some people think matter. The input to the power supply unit that delivers the high voltage that the laser needs has a power level input pin. You can vary this pin from 0 volts to 5 volts to get the intend power level. The Analogue version literally does this, it varies the power to this pin to give the required power. The Digital version however doesn't do this. Instead it uses PWM. PWM stands for Pulse Width Modulation. Simply put it means in any given time frame (in this lasers case 50 microsecond slices) the controller will put 5v on the pin for X amount of time and 0v on the pin for Y amount of time, X+Y being equal to the timeslot length of 50 microseconds. This means that having a very short 5v or "ON" length and a long 0v or "OFF" length will fire the laser for a short amount of time in the timeslot. Repeat this hundreds of times a second and you get lots of short pulses.

If you want high power the ON pulse will be long and the OFF pulse short, giving over time an average or more ON than OFF. At full power the on pulse is the full length of the timeslot, effectively giving always on. Doing it this way means the laser is never at half power for example, just at full power for half the time. The results in the actual cut are the same but some argue that running the laser at full power is bad for it and it wears out quicker, and using PWM means it is on full power, even if only in small bursts, all of the time. Others argue that the first arguments are unfounded and the laser life is rated as (time used * power level), which is essentially the same with both techniques. I've yet to find a definitive answer on this.

2) Air assist is a technique used to increase cutting depth and reduce smoke and heat damage to the material being cut. Air assist simply blows air directly at the point where the laser is cutting, cooling the material a little and blowing away smoke and debris caused by the cut. This increases the cut depth as the smoke and debris can get in the way of the laser beam and reduce its power.

3) Moshi-draw is the original software that came with the first K40 models. It is still shipped with some today. It is not nice software and barely allows you to use your laser cutter. It should be avoided at all costs. Early revisions didn't even let you cut, only engrave. Also, the versions I've seen being supplied are XP compatible only. How many people still have an XP PC? Laser-draw is the newer release which handles cutting and engraving, runs on Windows 7 and is at least usable. Preferably you want Corel-Laser. This is a copy of Corel-Draw (a half decent-ish vector art package) with a plugin for the laser cutter. Unfortunately because the machine is locked to a supplied protection dongle, you can't just use any software with it. you must use the supplied software. Many people use third party software to design their cuts / engraving and then import a save file into Corel-Laser or Laser-Draw.

4) I felt the location of the device was very important. There was very little chance that I would get away without paying import duty, which I know can fluctuate by exchange rate and service charge of the courier. And I assumed (wrongly) that if I found a UK supplier that they would have at least checked the machine for major damage before shipping it on to me. I also assumed (wrongly) that I could deal with a local seller in case of any problems.

5) I was prepared to pay between £500 and £600, but obviously I wanted it as cheap as possible with the features I needed. In the end the choice was half made for me. A batch of cutters came on eBay for £350 including delivery. They were from a UK supplier. They had a digital power setting. They had Laser-Draw and Corel-Laser but unfortunately didn't have Air Assist. However at £350 I didn't want to miss out. So I pressed buy one lunch time and began worrying.

Since this post, some sellers are as low as £320 including delivery.

It Begins

So about 4 months ago I decided I wanted a laser cutter. The reasons weren't particularly rational, but I managed to convince myself I needed one. I started trawling eBay and came across the ubiquitous K40. A 40 watt Chinese laser cutter advertised as the cheapest in the world (and for good reason). These go for around £500-£600 direct from China.

My plan was to buy a cheap second hand one for a few hundred pounds. However, their seemed no such thing. There's a high demand, not just for cheap laser cutters, but for units already in the country and in good working order. Apparently a high percentage of machines arriving from China were broken in a verity of ways. On top of this people were getting stung for import duty. I also discovered there were many variations of the same machine with additional extras and software versions. It wasn't going to be as easy as ordering a machine from the cheapest supplier and lasering away. (lasering is a word, right?)

The new plan was to buy a new machine with the specs and software I wanted and to try and reclaim the cost by doing bits of work for friends and maybe making the odd thing to sell on eBay. The purchase was signed off by my other half with the understanding that if it hadn't made its purchase price back in a year, it was to be sold.

So, cash in hand (or rather in PayPal) I started watching eBay for the right machine for the right price...