We recently had a specific job come through - a repeat of a past order - where we had 550 wooden plaques, and each one required laser engraving on them. Due to the level of detail on the plaque and the area covered, each plaque spent 20 minutes in the laser engraver.
The order in 2023 tied up our large laser cutters for several weeks while we processed this job, and caused some delays! So this year, we added on a new machine... introducing Minime!
Our other three lasers are bigger. Two of them, Pew-once and Blue-slicey, have a 1300mm x 900mm cutting area, and are fitted with 100W (watt) laser tubes. Lay-Z is a full sheet machine - it has a cutting area of 2450 x 1250mm, and is fitted with a 100W laser.
So 100W lasers work great for cutting! Lay-Z probably could do with a higher powered tube, but the 100W tube fitted is cutting through everything we need it to do. But for laser engraving - it's a different story. A little bit less power is needed for some engraving jobs.
But also, laser engraving jobs take time - basically, the laser has to scan back and forth over the piece to make up the image. To get a suitable resolution, we set ours to a 0.05mm scan interval. What does this mean? It means that it draws a line left to right, then moves up 0.05mm, and goes from right to left, and then moves up 0.05mm, and repeats the process until it's done. If your engraved image is 50mm tall, the laser head passes over the work 1,000 times to make up the image. As the image gets bigger and bigger, it needs more and more lines!
The glass tube lasers that we have are not super accurate, as compared to the RF ignited lasers commonly found on more expensive machines. It's not to say that glass tubes don't have their place, and they do an amazing job for their price point. One of the limitations with glass tube lasers is their low power modes. We program the lasers to operate at a "percentage power". The actual output power varies between tubes as they're not super calibrated. But there is a minimum power before they'll turn on. For Pew-once, this is quite high, at around 15% - so extrapolating, 15W of power. Blue-slicey's current tube is a bit lower - 11%. Lay-Z's current tube got down to about 8%. But that's still 8W of power you're applying to the material. (This actually does cover off a lot of jobs, but still, a lighter touch would be nice. Pun intended!).
Sometimes you want a little bit less power for some engraving jobs! So that's where you need a lower power tube.
And then, the other side is that some engraving jobs tie up cutting machines. Let's say you have a job where you're engraving an A5 sized plaque - 210mm x 148mm - but you're tying up a machine with a 1200mm x 900mm bed for the 22 minutes it takes to do the engraving... the bigger machines are more economical if they're kept busy cutting larger jobs.
Minime has a smaller cutting bed - 600mm x 400mm - and a much smaller 50W tube. The current tube turns on at about 8% power, which means it's lowest output is 4W. Excellent!
As it's a separate machine, and it's not as ideal for cutting, it can take on the longer engraving jobs, leaving the higher power laser cutters free for general cutting, of which they are consistently busy with. It can just sit in the corner and do it's job, until it's time to reload it!
Before we purchased this machine, we did some research. The reviews on this machine were basically that it's solid, but it does have some mechanical and electrical issues. Someone who has some experience with fixing and working machines will be able to modify or fix them - and that describes me. I've become quite experienced with maintaining and repairing our current laser cutters. So I knew there would be work to do - but at that price, it's hard to ignore.
For beginners, it actually includes a lot of useful features and components. Although we bypassed most of them to fit with our setup, but for someone without the workshop setup that we have, it makes a great starting point.
The machine shipped with a 60W laser tube. But some very quick testing showed that it was the cheapest possible tube, and didn't have the correct beam output. The below photo shows a 1 second pulse, on 50% power. It should be a complete circle, but you can see here that it's not putting all of it's power into a single combined beam.
I contacted support to see if I could arrange a replacement. Their response is that the beam output was fine for cutting. Technically, they're correct; you would be able to cut with that beam output - kinda. But I really needed the machine for laser engraving, and that needed a much finer and normal beam pattern.
Long story short - they wouldn't replace the tube. So I had to purchase another tube. They had several varieties - a "super cheap" option which is what they had supplied, and a "middle range" option that was twice the price. Or we could switch to another supplier who had top of the line tubes, but that was four times the price. So I settled for a middle range option, replacing it with a 50W tube instead. It wasn't that expensive, fortunately, and arrived 7 days later.
The second tube was perfect, and the output power was well above my expectations - and gave a perfect circle in the output. So that was sorted fairly easily!
The glass tubes in these machines require water cooling to operate correctly. There are two different types of water coolers - passive and active ones. The passive ones are basically a water tank with a radiator, and rely on cooling using the ambient temperature. As a result, the water is generally around room temperature for the lasers, and sometimes higher.
The active ones have compressor chillers in them, like your fridge, and use this to cool the water. They can be programmed to keep the water at a certain temperature (although the default is to keep it a few degrees below room temperature). We always have active chillers on our machines, and I have programmed them all to keep the water at 20°C all year round. From our experience, this is the best temperature to keep the tubes at for the longest service life and most stable output. Pew-once's tube has always been operated at 20° and it's now going on it's 8th year in service - well beyond the manufacturers suggested 2 year lifespan. The chillers that we have - CW-5000 series - don't even blink in summer and happily keep the water at 20° even when the temperature in the workshop reaches 40°C!
This little machine came with a built in passive cooler, which is neat, as for small setups, it means that you don't need an extra piece of equipment. However, for our uses, where the machine will be running for 8 hours a day, and running in the summer months, an active chiller was essential. We added a separate CW-5200 chiller to this machine, bypassing the internal chiller in doing so.
Normally, the chillers have an alarm output which is connected to the laser cutter, and triggers the "Water protect" input on the controllers. This prevents the laser from firing if there is no water running through the tube, which will instantly damage it. For all our other machines, this is connected from the chiller directly to the laser controller, which allows the controller to pause the job in case of an issue. For this machine, it actually had a water flow sensor built into it, so I saw no need to make any changes to this - I kept it inline as it was and connected to the controller. Problem solved!
The X drive belt wasn't at the correct heights for the carriage... resulting in some loss of accuracy! It's very minor, but this means it would move slightly faster at the ends of the gantry and slightly slower in the middle. For most applications, this wouldn't be an issue, but I was doing relatively high speed engraving, so I kind of needed this to be correct!
In addition, all of our other machines have a 3:1 belt stepdown on the X motor, to improve the torque on X gantry, as bigger machines have bigger laser heads. This one didn't have a stepdown and just connected the motor directly to the belt. This wasn't wrong or inappropriate, but can affect the speeds that the machine can be operated at.
However, I had a spare HBS-57 closed-loop stepper motor from another machine. As it's closed loop, it will much more accurately be at the correct position than a standard open loop stepper motor. Also, this thing runs at about 6A at peak too, so it's no slouch - it's a powerful bit of kit! It is the standard NEMA34 size, which matched what the existing X motor was, so it was easy to switch it over. I also replaced the bracket which then made everything sit at the right heights, solving all those issues!
And in practice, it's worked - we run this one at up to 400mm/s during engraving and it doesn't skip, move, or miss a beat. Normally we operate it at around 250mm/s to get the best detail with the laser tube that we have. It certainly won't do the 3000mm/s that you get on the very high end machines, but for a tenth of the price, I'll accept this machine.
As I was trying to optically align the machine, I was moving the gantry back and forth. I noticed that at the front of the machine, on the left, it was lined up fine, but on the right, only at the front, the laser beam jumped to the side. As soon as you move it back 10mm, it jumped back to the correct location.
After some head scratching and inspection of the machine, I found the fault. The manufacturer has installed two bolts on the Y rail support bars to act as a mechanical stop to prevent the gantry from coming too far forward. Most machines have end caps on the linear rails that prevent this, but they've omitted them on this machine. Also, the machine under normal operation will stop itself before the ends, unless it's had a positioning error during operation. But this is rare.
In this case, the one on the right hand side was too close, and when you brought the gantry all the way forward, it ran into that end stop, and then twisted the gantry!
Once I figured that out, and made sure there was enough linear rail left (yes, about 15mm), I removed the bolt, and that was fixed.
On the laser nozzle, the focus lens is kept in place with a circular screw on top. As part of my alignment, I replace the lens with a piece of acrylic and fire a test beam - what I'm doing is testing that the beam is travelling straight down the nozzle.
I only did this a few times, but I managed to strip out the thread inside the tube. I suspect it was machined slightly too large to begin with! However, I had a spare head from another project, and the thread of the whole nozzle assembly fit this head. The lens size was different (20mm, instead of the supplier 12mm), but I had spares anyway, so this was changed over with great success. The new nozzle had a better fit and this was the one put into production.
The machine comes with a built in air pump, that provides the air assist for the machine. It's not a bad pump, actually! However, we run all our machines off a large compressed air and air dryer system, and keep the air assist pressure at 30psi. Which is much more than the built in air pump! So we bypassed the air pump and added a connector on the back of the machine to accept air from our compressed air system.
Also, we added a solenoid to the laser cutter, so the machine can turn the air assist on and off itself, programmed by the computer. I already had spares on the shelf as I like to keep them in case one fails! This means that you're not using compressed air when you don't need to use it, and also means that you can turn it off for each layer - some engraving jobs need the air assist turned off to achieve the right results. But you definitely need it for cutting - no air means you're likely to get a fire, and also the quality of the cut is improved so much by higher air pressure.
The laser controller already has an output dedicated to do this; you just have to hook up the solenoid!
Another nice feature of this machine was a built in fan for fume extraction. It even had an activated carbon filter to remove some of the odor! It was a 200mm, 240v fan in the back of the machine. I'm impressed; it's quite useful for a machine without our workshop resources. You'll still want to vent this outside immediately though - the activated carbon filter is not enough by itself.
In our case, we have other extraction systems in the workshop, so we didn't need this one. I bypassed and removed the fan and filter. The extraction available there was a 150mm duct, so I had to cut an adapter to bolt inside the back of the machine to make the 200mm hole into a 150mm hole. Then I could connect it to the existing extraction system. Job done!
The machine was fitted with a fixed in honeycomb table. This was screwed to the table lift frame directly and couldn't be removed.
Our other machines are fitted with blade tables, and we have honeycomb tables that we take on and off as we need to. Honeycomb beds have a lot of "flashback" on the materials, where the laser reflects off the honeycomb table and onto the back of the workpiece, often damaging it. We only use the honeycomb table where we absolutely have to, for things where the back finish isn't important, or it contains small parts of a larger item that can fall through the blade table and stick up and cause issues. So this machine having a fixed honeycomb table was a bit of an issue!
In addition, the honeycomb table wasn't level. It was slightly higher (about 1.5mm) in the middle, just pushing that section out of focus. There was no way to adjust this either.
While the honeycomb table got us through our initial engraving job, as it didn't involve cutting, it needed to be replaced. So we took out the table, and using spare blades from an older machine, some laser cut brackets, and some aluminium extrusion, we made a blade table.
In addition, I used a piece of aluminum composite panel affixed to the back and underneath the blade table. This was angled down to the front. As we cut small piece, these will fall down and be directed to the front of the machine, so we can retrieve them. The collection box was a little bit rough in the end, but it will do for now and allow us to more easily collect earring studs as they're finished.
All of our machines report their status - busy or idle - to the dashboard. There are several dashboards around the workshop, and the dashboards announce when a machine has finished - so you can go and reload it! This is most useful for the printers in the front room, as you can't easily hear them from the workshop to know when they're done - so having the dashboard announce this is a great addition.
This machine was no exception! To provide this output, a small ESP32 board running Tasmota was installed inside the machine, and connected to the status output of the laser controller. This then connects via Wifi, and reports the status via MQTT to our customised instance of Node-Red. The Node-Red instance determines what to do with the status, works out timings, and passes along the machine status.
The other thing that we use this for is to automatically start the central extraction fans when a job starts. Then, when a job finishes, the system runs the fans for another 5 minutes to clear any remaining fumes, and then shuts the fans down to save power and reduce workshop noise. It's been fantastic to have this capability and not need to think about managing the fans automatically.
The online information said that it "was at a convenient working height". Maybe if you're a toddler! But for adults, it was a little low to the ground. But these machines are intended to be used on top of a desk. In our case, I built a mini platform from scrap materials I had around, to raise it up 560mm. The cavity underneath was also a convenient spot to locate the active water chiller too, and keep it out of the way.
As I said before, it was a cheap machine. But there were some really good things in it, especially compared to other cheap machines that I've seen recently.
Would we buy one again? Absolutely! For the price, and with some time spent on modifications and tuning, it's an excellent little machine. You couldn't build one for a similar price yourself and end up with the same result. However, we wouldn't recommend this for a first machine, due to the minor issues with it that would require fixing and modifications. But if you're handy, and have some time and patience, you can certainly work through it.
There are other machines available that are more expensive, that are more turn-key, and wouldn't require any modifications to get working. These machines would be better for beginners - the technology and what's included is improving all the time, and some of the home hobby machines are now quite capable for small production.
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