There are people around me who think I’m crazy. And they are probably right. Who else would buy a machine from someone he does not know. I have to pay upfront. It is not clear how things will get delivered, what gets delivered, or if it gets delivered at all. Up to the point I can lose the money I have spent. Best of all: that machine is dangerous enough to potentially kill me. And it has the potential to put my home on fire too. Well, that sounds like an exciting weekend project, or not?
We do have one of these expensive laser cutting machines in our FabLab at the Lucerne University, a 100 Watt AKJ-6090. Great and professional machine! Using it requires advance planning (the FabLab is open Tuesday, Wednesday and Thursday). I learned with using a 3D printer that faster cycles makes a huge difference, especially doing projects on weekends.
So I have followed many these ‘ultra cheap Chinese laser cutter’ stories you can buy on eBay (just search the internet for ‘k40 laser cutter’, or see this Hackaday lead article). And some of them were indeed ‘horror’ stories. The general consent seemed to be that these machines get better and better, and you get what you pay for. Fair for me.
What still was a concern for me was the software part: it seems many of these machines work with a CorelDraw (hacked?) version. Or LaserDRW, a piece of software I consider as ‘not so easy to use’. So all the software was rather disappointing to me. So I had put the idea of using a laser cutter aside.
What finally triggered again my interest was an article published on Hackaday: [Scorch] has reverse engineered that protocol to the commonly used M2 nano controller board (see “K40 Whisperer” and published his work as open source and published everything on www.scorchworks.com/K40whisperer/k40whisperer.html. With his software, it gets as simple as that:
- Create the drawings with red, black and blue color e.g. in Inkscape, and save it as .svg or .dxf file
- Open it in K40 Whisperer software and engrave and cut the work.
That was exactly what I was looking! All what I needed was now a decent laser cutter with that C6879-LASER-M2 board and hope for the best.
After doing some research, it was clear to me that I did *not* want to go for one of these ultra cheap K40 ‘blue boxes’ which one can buy for less than $500 on eBay. What I was looking for was:
- Larger cutting/engraving area than 31x22cm ==> 40x40cm
More power than the 40 Watt ==> 50 Watt
Of course it has to have the M2 nano board, otherwise I cannot use the [Scorch] software. And I wanted to have a few extras which most users of the K40 end up adding:
- Air assist (air flowing to the laser nozzle) to lower fire risks
- Bed leveling to move the bed up and down
- Laser pointer for the laser head
- Minimum safety features like an emergency stop button
- Honeycomb table
Ordering the Machine
After doing a lot of searching and weighting in pros and cons, I have found a seller on AliExpress which had what I was looking for:
The problem with these offers on AliExpress (or Ebay, etc) is that the sellers seem to copy-paste the specs and images, and it is really hard to tell how reliable a seller is. Can I trust reviews or are they fake as well?
I ended up with a seller which seemed to have sold several of these machines in the past year, and his store was specialized for CNC and laser machines. Most important he seemed to have shipped items to Europe to the destination address and offered registered shipping with DHL and others. I saw others with no clear sign that they ship to the closest sea port only and you have to pick it up there and deal with customs/etc.
It was not the cheapest offer for this kind of machine, but still at an amazing low price of $750 (!!!). There is some buyer protection as well on AliExpress, so I thought maybe the risk of loosing that money is worth what I could get?
So I placed the order and hoped for the best.
Payment got accepted, and then the first thing: the seller needed an extra $150 for shipping it by DHL to Switzerland :-(. I could have declined that and cancel the order. After some back and forth, I agreed, and things were going well and I received a tracking number.
Unboxing, Part 1
The tracking number location came closer and closer, and this Friday it finally arrived. The DHL courier rang at the door, and with high expectations I did open the door and received the package:
A silicon adhesive sealant plus one (in)famous USB dongle as the key for a laser cutter software. Yes, it came from the seller, and yes it was that tracking number I had received.
You probably have heard of all the horror stories about someone selling a mobile phone and then you receive a toy version or only the enclosure? Should I have received for that $750 only that software dongle which is sold around $50 on eBay? 😦
I immediately contacted the seller, and he responded with this:
“machine will be reach you soon friend no.worry,send separate,because usb is hard to send together with machine,patient please friend”
And indeed: a few hours later, another DHL courier was staying at the front door, and this time this was more promising 🙂 :
Unboxing, Part 2
Open up the box with removing all the nails, and it indeed had a machine in it:
Now if you remember the seller image from above, this is not the machine I have ordered: the colors are very different, and the design is somewhat different too.
But as I did not order that thing to match my living room furniture, I was ok with that and continued working to get the machine out of the box.
Apart of that foil on the top, there was nothing to protect the machine on the sides. That is somewhat questionably, but obviously the machine did not take any damage that way.
Inside the machine, a plastic container:
Which had all the other small parts in it:
Which includes a burned software CD-R, USB cable, air pump, water pump and parts for the fume extraction:
Under the plastic container, the honeycomb platform secured with zip tie:
The laser head was secured in place:
The bottom revealed some holes and is prepared to get some rollers or leveling feet:
Overall, the machine is looking really nice, and the enclosure makes a good impression:
Checked the laser tube: one of my nightmares would be a broken tube, but everything looked ok:
The laser tube is supposed to run for about 1000-1500 hours, but who knows? I have seen reports that the tube was not working after a few hours, so we have to see.
The tube was filled with water, so that tube seems to be tested. But no label or brand, so I hope this is a 50W tube and not a 40W one. We will see how much this tube is able to cut.
Below a picture of the first laser mirror. Notice the springs are hold back by two nails: simple and works :-):
The high voltage connection of the tube looked like many others I have seen: wires filled with silicone to make the connection (weird, but that seems the standard way):
The laser tube ground connection usually uses the same kind of ‘wires wrapped around and then filled with silicone), but that one did not look safe to me:
I decided to secure the ground using a pice of shrink tube so the ground wire cannot easily disconnect:
Switches and Tubes
On the backside, the pipes for cooling water and air assist.
I checked the connection/resistance between the extra GND connector and the GND of the power plug and it was OK. The wiring of the single-phase electrical connection was OK with proper grounding.
Near the main power there are two auxiliary power sockets for the water pump and air pump, both with US connectors.
💡 The two auxiliary plugs are on power when the machine is turned on. They don’t hold the plugs very well, so they can easily fall off. This is a problem as with this cooling or air assist might not be working and can damage the machine.
There is an emergency stop button on the front plus the switch to turn on the laser power supply (horizontal is ON, vertical is OFF): I think I will add a better label for it.
On the top there is a list of warnings, although I’m not sure what “water without sundries” means?
The front panel is easily understood: Main power switch, push buttons for moving the honeycomb up and down, laser power (percentage) indication and buttons to change it. A test button to fire the laser and a laser LED indicating if the laser is firing:
The electronics are behind the side door:
Things wired in a reasonable way. In my view the power supply would deserve an enclosure:
Most important, it uses the M2 Nano board which is supported by the K40 Whisperer software:
USB connection from the M2 Nano board to the PC on the outside:
The cables to the laser head:
In the middle the high voltage laser power supply with the filter in the background:
Below the high voltage connector to the laser tube and the backside wiring:
Everything looked pretty solid with proper shrink tubing. Sure a few cables could have been fixed better, but that’s something I plan to upgrade.
The first thing was to test with a multimeter the grounding and electrical connections of the machine. Everything was OK, and the power supplies and pumps were rated for the 230V I’m using. I checked this because of horror stories about K40 machines which had things wired up in a wrong way.
Mirrors and Laser Path
A closer inspection of the mirrors showed a fingerprint or similar:
I had to clean this and the other one near the tube with Ethanol and cotton swabs:
After that, the mirrors were clean:
I used the common ‘post-it burning method’ to verify the laser path. All the mirrors seemed to be properly perpendicular aligned. Only the beam hitting the last mirror was really on the edge:
So I had to adjust the laser tube itself (see http://justaddsharks.co.uk/support/laser-beam-alignment-guide) and going through a whole of ‘post-it test fire procedure’ to get the laser path perpendicular:
With the result that the beam now is hitting the center of the last mirror in a perfect way:
Inside the Machine
The machine comes with a nice internal LED light:
Detail of the laser head with air assist and laser pointer:
The machine features a leveling bed. When cleaning up the machine after removing the honeycomb from some polystyrene, I noticed that a washer. That washer (and missing bolt) came from the edge bed. Nothing serious and easy to fix with a new bolt.
This reminded me to check other parts, and I have found that the screw for one of the end switches needs to be tighten up:
On the bottom plate there is a round hole (not sure for what this one is?):
A DC motor with a chain is used to level the bed:
The motor turns forward or backward with the green (up) and red (down) push buttons on the front panel. So the leveling is manual which is what I expected.
But the red (up) button had an issue: I pressed it once, and the bed did not stop moving up: I had to power off the machine to stop it. The problem was the up push button which closed the contact, but did not release it. The problem was because when the cables have been put onto the button, the contacts got pushed too much into the button. Fixed with disassembling the button and putting the cables on it without pushing the contacts into the button. That fixed it.
I consider to replace the button with better quality ones. Otherwise leveling works very well.
The CD-R had had a 519 MByte 460M2.rar file on it. It included
Anyway, I was going to use the K40 Whisperer software, so I did not need all the extra software, but still good to have it.
The documentation is a mixture of Chinese and English, and better than I expected it (Google translate?). With my research upfront using the many YouTube videos and online tutorials for the K40 there was nothing really new, except one thing: I was wondering what that small plastic part is for. First I thought it was a kind of test prove, but it turned out it is to set the distance between the laser head and the target to 10 mm:
There is an excellent tutorial video about the importance of laser focus settings here: https://www.youtube.com/watch?v=Eg6THrEdleo
It included a folder with more pictures and a video how to adjust the laser beam and path, some information in English and some in Chinese:
That information was not really new to me, as I did some reasearch upfront. There are plenty of good tutorials available like this one on YouTube: https://www.youtube.com/watch?v=KhhOHUe_b6o
The K40 Whisperer software worked perfectly for me.
The only issue I have is that my laser machine is using the right upper corner for the zero position, while the K40 uses the left upper corner. Below the first test run with Raster engrave (10% laser power, 100mm/sec):
Fixed it to flip the graphic horizontally in Inkscape as a workaround:
As the K40 Whisperer software is open source, I will look into ways to add this as an option to the software.
One upgrade I did is to spend a metal fume extractor pipe instead of the delivered plastic one. And yes, I placed a fire extinguisher nearby too:
For the cooling system I’m using 5 liter of deionized water as used for lead batteries. The lid avoids contamination of the water, and added algicide keeps the water fresh (I hope). Otherwise I have more water so I can exchange it.
I attached the container to the machine so I can move it around.
💡 First I had the water outlet pipe outside the water to see if the pump is working. But this drained the water outside of the laser tube when the pump is not running. This creates air bubbles inside the tube which can be a problem. I have been running the pump for a long time at the beginning to remove any air bubbles from the pipe, and to avoid air to get into the system the outlet pipe under the water surface. I can feel the water container vibration to check if the pump is running or not (just to be sure). I need to think about a good automatic way to check the water pump is running.
Below some samples from the first plywood cutting tests:
With 10mm/sec, cutting 4 mm Plywood worked very well with 50% laser power. With 45% or 40% it did not always cut through. For 5 mm plywood I had good results with 80% laser power, 70-75% worked sometimes too. Overall this is what I expected. I still have to run tests with MDF and PMMA.
Here are a few things I consider as extra upgrades I could work on in the future:
- Additional LED light inside the cutter to better illuminate the cutting area. The cover has a tinted polycarbonate sheet (good!), but it would be good to be able to monitor better while it is cutting/engraving.
- Better air assist and water pump sockets: I fixed the cables, but they still could fall out.
- Ability to turn on/off air assist: the air blast makes a kind of nasty sound.
- Water temperature monitoring: to avoid that the cooling water temperature increases too much. Maybe an active cooler water chiller.
- Cover safety switch, to turn off the laser if the cover is open
- Laserhead autofocus sensor: this would help to measure the distance between laser and target.
- Magnets to hold the target in place: useful especially for small and light things, as the air assist might move it or because the plywood is not perfectly aligned.
- Corner alignment helper: that way I can position the wood/etc always the same way. That would allow to cut thicker material (see https://www.youtube.com/watch?v=DQXuzTTf2QE).
Maybe more will come up :-).
It took a weekend and some work, but so far I’m very happy with that machine. I think I got a ton of value for that money spent. Yes, such a laser engraving and cutting machine is definitely not a consumer product and not comparable with a professional one. It requires technical knowledge, and I have learned a lot of new things. The laser power of 50W and the high voltage are definitely very dangerous, and such a machine *never* shall be operated unattended. The internet is full of good tutorials and information, and it helped me to tweak the machine so I can successfully use it. It greatly extends my maker capabilities, and I have tons of great projects in mind :-).
In case you are considering to do the same thing: be aware that things are always different. Installing and using such a machine requires time and preparation, but is very rewarding. Reach out for advice and help in your local maker space. With this I hope that this article is helpful for your own adventures.
- FabLab Luzerne: http://fablab-luzern.ch/
- Tales of a cheap chinese laser cutter: http://hackaday.com/2017/02/22/tales-of-a-cheap-chinese-laser-cutter/
- Hackaday article: http://hackaday.com/2017/07/19/take-control-of-your-cheap-laser-cutter/
- K40 Whisperer: http://www.scorchworks.com/Blog/k40-whisperer-k40-cheap-chinese-laser-control-software/
- K40 Whisperer web page: www.scorchworks.com/K40whisperer/k40whisperer.html
- Good introduction about laser mirror adjustments: https://www.youtube.com/watch?v=KhhOHUe_b6o
- Tutorial about laser focus point: https://www.youtube.com/watch?v=Eg6THrEdleo
- Another useful laser mirror adjustment guide: http://justaddsharks.co.uk/support/laser-beam-alignment-guide