CNC lasers for cutting and engraving
jacquesmattheij.com
jacquesmattheij.com
https://github.com/tlalexander/large_format_laser_cutter
I never finished making the youtube video for it, but I have a partially completed video that lacks a voiceover or proper edits for the second half. However it shows the operation of the system and offers some additional detail:
https://github.com/tlalexander/large_format_laser_cutter/iss...
Notably the design includes a built in raspberry-pi based pattern scanner which can be used to scan in clothes to make copies (with some manual work in inkscape) and can be used to scan in paper sewing patterns.
Done. How is the farming robot coming along? I have not kept up the last couple of months.
The robot is coming along! We completed a ground up redesign of the robot and it is waking up every day in the field and running test cycles on solar power. I have been refining the electronics. I got back new revs of the motherboard and motor controllers and both work well, though I already see additional changes I want to make. I designed a new steering angle sensor that dramatically simplifies the corner assembly. We are working on moving the shop closer to my house so I can go in to low volume production on prototypes. This will allow us to get long term reliability testing done! Then we would start looking at kit sales and publishing official recommended designs for those that want to make their own.
It has been a hell of a slog, so I have not produced a video in a while. Hope to get one out in 1H 2024.
I did have lunch with a laser safety engineer about 20 years ago who scared the shit out of me talking about problems with blue lasers. That deterred me from ever playing with for example those big handheld laser pointers you can buy. But this module is about 30mm square and sits 5mm from the fabric, so not much light really escapes anyway. One important consideration is that there are no metal screws underneath the lasing area, so I'm not going to get dangerous reflections.
Anyway I lived alone and had no pets and I was always present while it operated. For my use I felt the safety was adequate, but obviously for something like university use it would need a full enclosure. This version is a prototype slash proof of concept.
If anyone things OSHA has a handle on this issue, they are delusional. Without a major accident happening, most of these small shops can play by their own rules simply because the body enforcing them is stretched ridiculously thin.
So, thank you for asking this. It's insane to me how many do not bother to ask.
Amazing project!
The burned edge for synthetics is itchy. You can either design the garment to hide that edge from skin contact, or design your cuts to be a bit large and then snip off the edge that would be in skin contact (beats manually tracing out the entire pattern). The burned edge for cotton is nicer.
I disagree with this. Both diode and tube lasers can instantly blind you. But diode lasers can be a pain to block - because they’re in the visible spectrum you need specialized blocking materials that are opaque in that very specific part of the visible spectrum. Worse still, many have leakage into other frequencies, making them even more difficult to block. On the flip side, a co2 tube is much simpler - some common and readily available plastics transparent to visible light are opaque to the IR wavelengths emitted by co2 tubes, dramatically simplifying blocking material selection.
You should never operate any sort of cutting laser without an enclosure and safety goggles, and it’s MUCH easier to do this for co2 lasers.
These weren't small errors, > 2 mm in either axis across the 61 cm x 61 cm work area of the machine. But now that it has been set up properly it is quite usable.
A 'real' machine has a calibration procedure that will allow you to correct for such errors as well as a large variety of others but these cheap machines just output stepper pulses in fire-and-forget mode without any feedback at all besides the ability to re-home in case they get lost (and the homing switches are so crummy that I'm amazed they work at all). But that usually implies a ruined work piece.
The situation for visible diode lasers is much worse. Sure, the power tends to be lower, but they're still powerful enough that looking at a diffuse reflection will result in dangerous power densities on your retina. Unfortunately, the brain is really good at hiding this sort of damage, so it's possible to not notice until it's too late.
1.064um fiber lasers are the worst of both worlds. Very high powers, invisible so you have no idea how much stray light is getting out or if you're staring at a reflection, and expensive + hard to verify safety glasses.
I like doing things with high power lasers (next up for the collection is probably a 355nm ns system?), but am glad that I had to take a lot of laser safety training before I bough my first big laser source.
The worst you'll get is 100% illumination on all pixels on the LCD inside the headset.
You can't stare at the Sun, but you can stare at a video of the Sun.
Edit: I've updated the article with a hopefully better text and a reference to your comment, if you could review it and indicate if I should make further modifications I'd be very grateful.
That being said, it's also great to see the beam's location, so one possible solution is to mix in low-power red/green laser into your cutting beam. It can be as simple as gluing a strand from a fiber optic cable next to the main cutting head.
Not relevant to laser cutting at those powers.
Think of it as (this is not perfectly right but good enough for this explanation):
unidirectional accuracy - I command a position from 0. Where am I?
bidirectional accuracy - I command a position from 0. Where am I? I command a position in the opposite direction. Where am I?
repeatability - I command a position from 0. Where am I? I command us back to zero. Where am I? Repeat. Compare results.
It is true that, given a single directional commanded position from 0, the accuracy is likely to be 0.1mm or better.
But one missing factor in whether that will be true repeatedly is not just how it is driven, but what is being driven. Is it lead screws? ball screws? gears on rack + pinion? Nothing?
If it's nothing, you will have repeatability issues, because both stepper motors alone, and stepper motors + belts, accumulate error through backlash.
It is possible to get a lot of the backlash out using the right types of belts or gearboxes or what have you.
But even at this price point, you probably want some mechanism (helical rack + pinion, ballscrew, etc) that ensures repeatability, to ensure your accuracy will be worthless.
BTW I would have expected accuracy would be quoted from a fixed reference point, that would coalesce all the repeatability scenarios you laid out into a single 'worst case', error-does-not-exceed value. (Are you implying with low accuracy but high repeatability you could get good results that are, conceptually, simply offset by whatever margin? Or that you'll get jagged edges / artifacts / incomplete or overdone cuts at scales below the stated accuracy threshold eg. if you have a corner approached by cuts from different ends?)
I've designed CNC gear for a living and I'm aware of the way things are done in industry. I think this low cost approach opens up an entirely now domain and if you're making boxes, wooden toys and decorative pieces the accuracy requirements are much less critical than they would be if you were to make parts for aerospace or such, but nobody is going to attempt to do that using a rig like this.
I even put out ads trying to hire someone that’s worked as an (electro)mechanical engineer at an inkjet company to hire on a contract basis but got no responses. It’s possible those are mainly outsourced - or that the know how turned into domain knowledge that can’t be reproduced these days!
backlash, variable friction, motor power variation due to voltage, belt stretch, most flexions of the frame — all of that should just be 'external disturbances' that the negative feedback system automatically corrects. only the position feedback itself (and the time of actuation of the inkjets) has to be precise, that's the magic of negative feedback
as for the optical strips and encoders, i figured that a 600dpi laser printer printing on laser printer transparency film should be able to print a light/dark transition every 42μm, though it might take some fiddling to get that to actually work. supposedly 1200×1200 dpi laser printers also exist on the market for US$300. the standard way inkjet printers do this seems to be with a slit that's only slightly wider than the size of a single stripe, but a second transparency with the same 50% black pattern would also work, producing a moiré pattern (though with a viewing angle of only 25° or so due to the thicknesses of the transparent films). let me know if this is unclear, i'll make an animation or something
with a quadrature cycle (as the inkjet printer sensors seem to use, according to the datasheets i've managed to find) every 84μm you get a full cycle, so you get a transition every 21μm and you know your position ±10.5μm. that's half a thou, good enough for machining a piston
if you don't truncate the brightness to one bit, though, you can measure the phase within the cycle to probably within a tenth of a cycle, so you get ±4μm
as for who did the mechanical engineering, i suspect that it's something like ten people in the world, half of them retired. dissecting printers from different decades i see an astounding degree of similarity from one decade to the next
Apropos machining pistons: the bigger issue with anything that needs a reliable 'Z' dimension on any kind of cutter like this (essentially a two-dimensional device) is that that third dimension is really only well specified at the point of focus. Outside of that it is more or less conical depending on the kind of cutter and the optics in case of a laser. Waterjet, plasma and laser all have different characteristics depending on what you cut with and in case of a laser the construction of the head and the kind of optics installed. Plasma also has work hardening effects that can not be ignored.
The only economical way to accurately cut large pieces of thick material is by using a heavy gantry mill or an EDM machine. Both will still be very costly and this sort of use is probably outside of the hobby arena anyway. If you need that kind of work piece I would suggest outsourcing it.
but i didn't mean to say that cheap inkjets contain no tight tolerances; they contain lots of tight tolerances. (the ones on the nozzles and on the traces on the integrated circuits are a lot smaller than the ones on the screws.) i meant to say that the in-operation movements of most of the parts of the printer don't have to be precise because negative feedback compensates for any errors they introduce
the printer doesn't make any screws or any holes in anything or screw in any screws, it just squirts ink onto paper, so there isn't a question of how precise the holes it makes are
> The only economical way to accurately cut large pieces of thick material [..]
Fortunately for most real-world applications the old maxim about size and required precision being inversely correlated tends to hold.
I was a die-hard subtractive machining zealot but I've slowly come around to appreciating 3D printers and they've made incredible strides in terms of capabilities and accuracy over the past decade. The hobbyist stuff still has some ways to go, but the exponential improvements are hard to ignore and I think it's become a viable suggestion for a lot of things were 2D machining used to reign king, at least where the end goal is to make something and not specifically to machine something.
But I still miss my machine shop :)
EDM is as slow as it was in the past, there have been incremental improvements but nothing that would make you go 'oh' and of course the waste in the wire is still as much a factor (and one that makes me dislike EDM but the capabilities are off the scale in terms of precision, cut depth and consistency, in machining everything has its price).
One thing that I've noticed the last couple of months is that you need to change your way of thinking about this stuff. If you 'can't make it' you need to think of what you can make and then adapt your design to that. This is far more productive than to stick to the 'proper' way of doing things. Suddenly two - admittedly - fairly crappy machines outperform my old shop in many ways. I really miss the ability that my 12 KW plasmacutter gave me in terms of cutting metal with accuracy and speed. But material hardening was a drawback as was the metal vapor and the conical kerf. By re-working some of the designs to use wood instead of metal and 3D printed parts where the 2D process isn't enough I find I can make almost anything that I could make before as long as it is for indoors use and strength isn't the main factor. Nothing beats metal and welding in that department.
Before getting a 3D printer and the laser cutter I would still cut metal, grind and weld pretty much regularly. But now it's a rarity, and I suspect that once I get the hang of high tech plastics that it will become even more so.
The operating principles of my original prototype [0] needed at least some degree of precision in the mechanical components because I had actual mechanically interfacing/interlocking parts, unlike a CNC/laser/inkjet where the head is effectively traveling "unobstructed" in free air (in the case of a CNC, creating its own void to "float" in as it goes along). There were two separate positions that needed to be tracked, the linear position (this discussion) and rotary position (for which a basic rotary optical encoder or a servo could be used).
The design of the prototype itself (machining issues aside) was sufficient for its time (late '00s) where it would have taken the place of a (then) $10-25k braille reader PC attachment, offering more characters while being available for orders of magnitude less but the world has changed so drastically in such a short time that I've had to rethink the design to be less of a PC attachment and more of a standalone "braille eReader" sort of thing, significantly complicating the mechanics and increasing the precision machining requirements. It would be a "page" composed of multiple such braille reader rows, belt-driven and either (somehow) individually drivable so one motor could drive all the rows or (preferably, if the optical encoder BOM costs could be driven down cheap enough) with a separate motor per row allowing for faster "page refreshes" (esp. important because it takes ~no time at all for a user to finish a line of text).
Here the complication becomes switching from internally actuated to externally actuated "braille discs" in a way that allows manipulating each "cell" sequentially with a drive head that moves from the start of line to the end — but also leaves the cells in an immobile position so they're not free floating and don't change when a user glides his or her finger over them to any degree in the y-axis (instead of purely in the x-axis). Additionally the size of the optical encoder element becomes an issue because there is simply not much room to cram things between each row of braille text.
My first thought to allow me to solve all these in one go was to mount each braille disc on an "electromagnetic clutch" of sorts, but I was left aghast at the price of those -- and none were miniature enough for my needs. I then tried to go old-school and use an arrangement of actual miniature magnets embedded into each braille disc so they would maintain their position until externally actuated with enough torque to overcome the magnetic inertia, but failed to prototype that with sufficient precision and couldn't find magnets that would hold strongly enough while being small enough to embed in a braille disc (and forget obtaining them within budget, at least at retail values).
Had (and still have) other ideas but the time/cost difficulties in prototyping and the limitations on mechanical tolerances of the available prototyping methods really put a damper on things.
It's funny, I used to post about this on HN deliberately off and on for years and that never went anywhere at all but this chance response has led to the most fruitful conversation I've had on it here!
The description of your machine has already made me wonder if it isn't feasible after all.
That is the middle ground that won't lose steps but isn't as powerful.
I agree linear motors are well overkill for this. They are mainly useful when you need very high acceleration, which isn't true here
In practice you'll cut at speeds low enough that these things aren't an immediate issue, though when you start to cut cardboard or paper at near maximum speeds there likely will be some artifacts.
I will try to find the limits of the machine to see at what speeds these issues become apparent. Given the flimsy construction I'm amazed at how well it does, to be honest I had not expected it to be as immediately usable as it is.
Cutting 18 mm plywood with a < 0.5 mm kerf and < 0.1 mm repeat accuracy - especially compared to all of the other tools I have access to - is incredibly precise. In metal it wouldn't be all that impressive, but that's not what this thing is intended to do.
Anyway, the article wasn't intended as a treatment on CNC accuracy issues, there are many more that the GP hasn't touched on (such as: positioning errors due to temperature variation, which with aluminum frames can be considerable, and frames being out-of-true).
It's a dancing pig: it dances, that's the amazing thing, how it holds up compared to industrial machines that cost 400x as much isn't all that relevant.
The rest i mostly agree with except maybe the 400x number. Seems high to get to a better level.
I'm actually quite surprised at this, I did not expect that to be the case. But: this is my first laser (previous CNC tooling: Lathe, Mill, plasmacutter, the latter a homebrew affair at 8x4') and the main advantage that it seems to have over the other tools that I worked with is that the gantry and the head are fairly light in comparison to what you would normally expect. Even a plasmacutter requires a movable Z in order to compensate for warp (or you will definitely have material strikes).
So the head is probably < 1 Kg all together and the gantry < 10. This most likely is the biggest factor in how with such a light and - bluntly - flimsy drive mechanism it works as well as it does. It's got less backpressure than a pen plotter would have, basically just the rolling resistance of the rollers and the drag from the airhose and a thin electrical cable. I did add a segmented chain for the main gantry to ensure the cables and hose can never get tangled.
As for the 400x, an industrial laser from a brand with a good rep runs between 20 and 40K, these open frame lasers sell from anywhere between 500 and a thousand $US, I mistakenly added a zero too much so you are right about that! I spent a whole day on writing that up and was super tired, I slept a bit since and it's much better now.
I think, these are sort of problems after you "level up". Lasers and 3d printers both have pretty light toolheads and no resistance. So you can get away with being pretty half assed with your stepper control, and still get results.
You're not wrong. But there's a big mountain of stuff to learn when starting with CNC stuff. Getting a cheap machine, figuring it out, tinkering with it, improving repeatability, these things are all part of how you get better. This is sort of a hobbyist diy mindset. Even if it's not a very good machine, you can still get results out of fusion360, or scad or whatever toolchain you work through.
Now, you're absolutely right, if you've got some cash burning a hole in your pocket, you can skip a lot of that machine tinkering hassle. pro level gear is absolutely magical. I'm more of a dabbler kinda guy, try it out, learn about it, if it seems cool 10x my investment in the hobby.
Anybody who wants to turn a laser cutter into a business is going to know all the stuff you've addressed. A hobbyist, they're going to need to not die from toxic gas from tanned leather. they're going to need to work out if they want to make stuff or if they want to tinker with the machine (both are totally valid).
To be super clear, I agree with all of your points. And it would be good to indicate the suffering you'll go through with a cheap machine. But, I'd argue a cheap machine can still be really fun. It all depends on what you're after.
Woodwork to within 0.1 mm is insanely precise. You won't be making watches with this, but a mechanical clock with wooden gears is well within the realm of the possible and your accuracy will be much better than that of the best woodworker using non-CNC tooling.
Drag racing has a super stock category, which is pretty much a normal car you buy and then mess with. Some folks are sponsored, but generally sponsorships are in the thousands of dollars range, not the millions, like pro funny car or top fuel would have. Most of the budget comes from folk's wallets and maybe winnings.
There are race car drivers, there are race car mechanics, and sometimes they're both the same person. Any _good_ driver is going to have some idea about how to turn a wrench. Any _good_ mechanic is going to have taken a few runs, and the fear of death rules out that particular career choice.
I think your point about the material is a good one. I think, that might also be a "level 2" skill. I think there is a huge amount of stuff to do to get a real sense of what CNC can do, and what a given person is able to do with a given setup. super beginner stuff like, what do I click to make the run go? is it connected right? What's a spline? Why is the enclosure orange? Just the safety stuff alone is pretty intense. And like, engaging the safety squint isn't going to help at all.
I'm very much an advocate for getting the shitty version to learn on. Maybe I learn bad practices, but I find I REALLY appreciate good tools. I have the tools I have because I finally understood what I needed and why it needed to be that way. Some of the tools in the box rarely get touched, but they're good enough when I need them.
Sorry to ramble at you, I guess I just needed to get that out.
_edit_
and of course, you're the author of the article. Ahh, it's been a rough week. I think it's a good intro.
As for the shitty version: it actually isn't all that shitty! Of course I'd like a larger bed and of course I'd like a more powerful laser. I'd like to be able to cut through two inches of steel with zero kerf. But in practice this is what I have and the easy solution is not to pine for the tool that you can imagine but to get the most out of the tool that you can afford and that you have.
for example in https://youtu.be/PAFBkgawH3w?t=2m10s he says he cut through a razor blade in 600 passes
EDM can do it too but it will be super slow.
i think it's common for tsmc to make hundreds of billions of small parts in one run with etching
The belts are usually quite good in quality, contrary to your assertion belt drives do not accumulate backlash (though they will have some it is more or less constant as long as you don't lose steps, which normally should not happen), have a Kevlar component in them to remove a lot of the stretch issues that you'd have with cheaper belts and either the gantry is moved with two steppers or there is a cross gantry shaft which operates a passive gear (without a motor) on the other side. Obviously this isn't perfect, the shaft is long enough that it will see some torsion so when moving fast one side will lag a bit and when you come to a sudden stop you'll see some overshoot. But even at very high speeds and long series of repetitions (100's) I've yet to see any backlash or 'slop' that is visible or measurable with the tools that I currently have at my disposal. This is funny because I totally expected to find a measurable positioning error but given a nice micrometer I find the positioning error when the machine comes to a stop after many 100's of meters of travel to be < 0.1 mm and positioning error from the origin to any point on the machine to be well within the acceptable.
The thing that you will notice is that because of the open construction of the frames that the machines aren't going to be square 'out of the box', and you'll spend quite a bit of time getting them to be just so.
I don't have access to an interferometer but if I can get my hands on one for bit by borrowing one somewhere I'll do some measurements on it but for now my simple tests suffice to show that the machine is quite usable and produces output that is dimensionally accurate to the point that it makes zero sense to farm out jobs to professional laser cutting services.
If I were cutting metal (which you won't be doing with a diode laser for obvious reasons) it would be a different matter, but even there in sheet cutting the tolerances on larger work are different than they are with for instance a mill or a lathe. You won't be making any press-fit shafts with a machine like this, nor will you be cutting gears with 1 mm teeth. For that kind of work it just isn't the right tool, and lasercutting isn't the right process. If you want that kind of precision in sheetmetal you would probably either use a mill (but then your workpieces will likely be small) or you'd etch your workpiece after a photographic process to create a mask.
When working in wood, cardboard or textile the precision that these cheap machines offer is ample.
Get laser safety goggles that are appropriate for the wavelength of your laser, and get them from a reputable source. Always wear them whenever the machine is powered.
Make sure to have a way to easily and quickly de-energize the laser for when stuff catches on fire, be it an e-stop button or using an outlet with a switch.
And don't ever cut PVC. It'll generate chlorine gas, which will either injure/kill you or corrode your machine.
Edit: update the article.
Something else I might add is don't try to cut plywood with phenolic resin. I'm not entirely sure how hazardous the fumes and residue are (probably the main risk is formaldehyde), but phenolic resin also just doesn't cut very well at all. At least, not with a CO2 laser. I'm not sure if diode lasers do better.
What seems to work well for me is to check the edge of the plywood -- if it looks like there's a thin black line between the plys, that means it's probably phenolic and it'll make a sooty mess if I try to cut it.
I found an old scrap of the plywood I had been using before and without those thin black lines and it cut fine. So, that's what I've been using ever since.
edit: link added.
https://www.theregister.com/2017/01/30/berkeley_maker_couple...
Edit: I thought that was familiar:
https://news.ycombinator.com/item?id=13507734
Edit2: it turned out to be CO2 poisoning after all.
Anyone have any good tricks to avoid that?
To remedy you can oversize the part a bit and then sand off the burned edge, you can lacquer or paint it to stop the carbonized wood from escaping (though adherence of lacquer and paint is poor on the burned edge) and you can (lightly) sandblast the pieces.
Edit: I've added this to the article in the 'wood' section.
I also upgraded my exhaust fan to make sure nothing got into the room. I got a variable speed DC fan so that I can leave it on a low speed after cutting something smelly to help the smell go outside until it dissipates.
I had the most issues with smell when I was using cheap wood from home Depot. When I switched to real Baltic birch the smell wasn't as bad so I think the other stuff had chemicals in it.
Acrylic still smells bad but it dissipates quickly.
Unfortunately, what I see lacking in high end laser CNC machine market is software and no separation between CAM programming and execution that exists for milling machines. There is no equivalent to G-code that can be generated on w/e software and then run on different machine. There are cases where this is impossible as due to the way it's done, it would quickly overload even large RAM memory capacities.
I'm old school enough that I can program G-codes by hand (and by heart), compared to normal programming it is super simple, you can pick it up in an afternoon. But for complex graphical work the automatic conversion to G-code from a drawing tool is a real time saver. CAD/CAM software tends to export in some 2D format for laser cutting, usually either a 2D DXF file or SVG. You then convert on the fly to G-code in the laser driver software.
Why can't you just refill the gas? Because the precise gas combination that makes for a stable, reliable laser tube was monopolized ages ago.
Because of that one trade secret, countless tubes end up in the trash and way more than necessary are manufactured. Classic case where monopolization of scientific knowledge can end in significant unnecessary waste.
I'me using observable notebooks to design some things https://observablehq.com/d/1117987aeab1be0d
IMHO if you are a beginner you should be very careful about cutting any material that hasn't been explicitly designed to be laser safe.
Edit: amped up the warning on leather, also added a more general version of that warning to the heading on materials.
https://www.tumblertrick.com/how-to-make-the-tumbler-trick-d...
This tool helps level the cup edges the best we can. My wife makes between 25 and 100 of these cups a month and this tool really helped her. We were using a digital level and having to create a design of the cup edge and figure out the angle for each brand and size. This gets rid of that complexity.
The laser is out of focus for the majority of the burn but it's in a range that allows it to work well on powder coated tumblers.
Specifically, we use a Creality Falcon 2 Diode 22W laser for tumblers. It's not, however, the machine I would recommend to others, for a number of reasons.
Some CAM software orient the trajectories so that the part is always on the same side of the trajectory (i.e. only G41 or G42 is used in a given NC file). This is what we do at https://nestandcut.com/.
A simple trick to check the shape of the spot is to set the beam to low power and to purposefully increase the Z as far as it will go and project the beam on a piece of black anodized aluminum. You'll very clearly see the alignment of the individual diodes and as you lower the Z you see them converge on what eventually will become the focal point. This gives you very useful hints about the shape of the cone, on my machine the cone is definitely oval (if not outright linear!) in cross section, far longer in X than in Y. This results in an ~ 30% penalty in cutting speed depending on the direction of travel. To ensure full penetration I have to set the machine 30% slower, whereas if the software compensated I'd be able to run the same speed with much more consistent kerf width as a result and less time wasted.
Ventilation is a must, I really think the manufacturers of this gear are doing their customers a disservice by suggesting that you can just use them in a dwelling.
edit: holy guacamole, that stuff is expensive!! I've found some but it is so expensive that I'll look around a bit longer to see if I can find a coupon for a test somewhere.
https://perlaplast-kunststofshop.nl/catalogsearch/result/?q=...
another local source:
Acrylic can be laser-cut, but polycarbonate in air, no.
https://majid.info/images/reddit/laser_dog_tag.jpg
https://majid.info/images/reddit/laser_pliers.jpg
https://majid.info/images/reddit/flash_drives.jpg
This is the specific model (EM-SMart Nova 18W):
https://www.em-smart.com/EM-Smart-Nova.html
I don't have a depth gauge but I would guess 0.1 to 0.2mm. It's with 10 passes, which takes about 8 minutes with a complicated pattern like the crest on the coin (stainless steel, about 20mm in diameter).
It doesn't work on brass or raw (not anodized) aluminum, not because of reflectivity but because they are thermally very conductive and don't heat up locally like steel or titanium would. The dog tags are mirror-polished and very reflective, but they engrave beautifully. On anodized aluminum, the laser just strips the anodizing, revealing the raw almunum underneath.
Repeatability is excellent on the galvo, otherwise it would not yield good results with multiple passes. I can't give a dpi rating because it is intrincally a vector machine, but here is a pic with a calibrated microscope showing a 1mm square grid superimposed:
https://majid.info/images/reddit/laser_engraving.jpg
Their rating is 0.01mm, which is probably optimistic. In any case, you can see the sparks the metal makes as it is ablated by the laser, that process is inherently a bit messy, just like you can't compare a laser printer's dpi with an inkjet's because the ink drops splatter:
https://majid.info/images/print_quality.jpeg
The working area is fairly small, about 20cm x 20cm x 10cm, pretty common for galvo heads. The limiting factor is the optics since the laser head itself is stationary and the lens needs to focus on the engraving plane. You focus by raising or lowering the head on a vertical rail using a knob. Some fancier models have motorized Z axes and autofocus cameras.
I've never tried on razor blades, I would assume it would punch through. It's likely thermal warping would yield unusable results, however.
No idea what the cost to run is, I doubt it's more than a couple hundred watts. The main cost is the laser, I paid $2000 for it on Black Friday special plus about $500 for the enclosure.
The brand of the engraver doesn't really matter, they are all assembled using the same lasers, galvos and lenses, just like most PCs are made from the same few components no matter whose brand sits on the faceplate, but getting support will be important. I had to fix mine because the red preview laser burned out. It's not too hard if you have any experience with computers and electronics (no soldering needed) but still a bit disconcerting.
The EZCAD 1.x software (Windows-only) is abysmal. I would strongly recommend getting the Mac-only Lightburn software instead if your laser is compatible (mine claimed to be but didn't in practice, and I had no interest in debugging this).
100μm deep is amazing! by cutting steel (and even stainless!) this machine is dramatically overdelivering on its process of marking metals. 100μm to 200μm is plenty thick enough to use it to cut holes in things, and if that only takes 10 passes, you're getting 10μm or 20μm per pass, which is also amazing
that suggests you might be able to manage aluminum foil, which is typically 10μm thick, and doesn't have all that extra aluminum behind the surface to heatsink it. and that would avoid the usual problems with making things from aluminum foil, which is that you can't do anything with it without wrinkling and/or tearing it
an alternative way to engrave or cut aluminum or brass might be to anodize or paint it first, use the laser to selectively strip off that surface layer, and then etch it with acids, bases, or electrolysis where the metal has been left unprotected
the markings in the micrograph seem to be perfectly sharp, straight, and smooth down to the resolution of the microscope, though the finest lines I see are on the order of 150μm across according to the grid (15px on a 104px grid). this suggests that the positioning repeatability is in the range of the specified 10μm, even if (as you say) the messy crater the laser creates is about 150μm across. 10μm out of a 200mm range is astounding resolution, that's 20k × 20k reliably distinguishable positions
the w&m levsha video i linked elsethread https://youtu.be/PAFBkgawH3w?t=2m10s did manage to cut parts out of razor blades (600 passes to get through 100μm) without any noticeable thermal warping, but i think his laser is weaker than yours; he can only ablate the metal oxide, not the metal itself. given that, it's surprising that his can mark brass and yours can't; possibly he's using a grade of brass with less copper and therefore lower conductivity, or maybe there's a relevant reflectivity difference which in effect makes his laser more powerful on brass than it is on steel
i'm guessing the cost to run is probably dominated by either the depreciation of the machine (say, a dollar a day whether you use it or not) or, with heavy use, the lifetime of the laser (say, 20k hours would give 10¢/hour) except that if i recall correctly you're in california where retail electricity is supposedly nearly 50¢ a kilowatt hour, which would be 10¢ an hour for a couple hundred watts. but with solar panels the energy cost would be about 20× less
has anybody reverse-engineered the protocol, i wonder?
Seen through the protective enclosure (hence the green color cast):
https://www.youtube.com/shorts/GVXb5z0TR7w
Taking it out and weeding it:
That said, I don't think it's that practical, getting the right focus took trial and error, and it's not all that repeatable.
how efficient is this? heat of vaporization of iron is 354 kilojoules per mole, which works out to 6.3 kilojoules per gram, plus another 3 kilojoules per gram or so to reach the boiling point. if i estimate your cut width as 100μm and the cut length as 60mm (600ms at 100mm/s, 18 frames at 30fps), that's about 1.3 mm³ of iron, about 10 mg, which should require about 90 joules to vaporize it. this is about 500 milliwatts over 3 minutes, which is a lot less than 14.4 watts, so probably most of the heat is being lost to things like reflection and conduction; maybe most of the focus spot isn't getting hot enough and only the center is actually boiling (though the sparks suggest that some of the iron is being ejected in liquid form)
i suspect it could become a lot more practical with automatic focus
The choices are either DIY ones off aliexpress or the more expensive ones like Shapeoko.
There are quite a few of these:
https://www.aliexpress.com/w/wholesale-cnc-router.html
Quality is all over the place and given the fact that they have a tool that creates backpressure (and that sometimes wants to 'climb' the workpiece depending on the direction of the cut) any kind of imperfection in the mechanism will immediately show up on the work product.
I posted a DIY one the other day that I think is pretty neat https://www.instructables.com/LOW-COST-DIY-500-CNC-MILL/ .
I don't think anything you buy of Ali or Amazon in this price range will ever be in 'it just works' territory, neither laser nor mill. They're barely functional and usually need quite a bit of tweaking to get them to work properly. And tbh I don't think the Shapeoko is that much better.
CNC milling is messy, you'll spend quite a bit of money in tooling and the work area is usually quite limited. If you want a larger machine and it still has to be affordable I'd shop around for an older industrial machine. It will be large and heavy but construction wise there isn't going to be anything small and lightweight that can begin to compete. If you're lucky you might even get a bunch of tooling with it.
I see all the caveats about the lasers and also the nasty fumes they make me deal with - hence the desire to go with a mill - a known devil to me.
Also, I work most of the time with Hardwoods and CNC mill is more appropriate for the task than the laser regardless of power.
I’ll keep a look out in marktplaats for any used CNC mills. I hadn’t thought of that.
If you want a CNC router that truly "just works", you're looking at spending five figures on something that's delivered by a semi truck. You can't escape the laws of physics, so a reliable and stable machine necessarily requires a big steel or cast iron frame.
I've had mine for years and love it.
Could you still test it wit EVA (ethylene-vinyl acetate) foam? I use it for prop-making. While it's easy to cut with knife, CNC laser would make that stage much faster.
A pain to get that DYI keyboard plate (no, I don't want to use a PCB).
It seems plasma/high energy laser cutters are a must.
Hydrogen production for one (you can imagine where that's going :) ), and you'll need some shield gas to make it work reliably. Cutting speed is going to be pretty impressive, edge quality not so much compared to a laser.
You'll want a beefy fiber laser and an industrial setup with regards to fume extraction, metal vapor isn't exactly healthy to breathe. Operating a machine of that power level in or near a residence is probably not the best idea unless you live remote. For work like that I'd probably outsource it, I do not have enough metal cutting projects that I need that capability in house and in an extreme case I can always break out the jigsaw (or even the grinder...) for a one-off. Not quite as precise but for most stuff I do that would be good enough.
I've been thinking about using them for Christmas lights.
My first response is: wrong process, I'd use a water cutter with an abrasive added to the water for this particular application. But my second response is: you can't be sure without trying, but I predict it will either not work at all or it will take an insane number of passes.
At Vancouver Hack Space we recently upgraded from LaserCAD (terrible software that came with our 80W CO2 laser cutter ~10 years ago) to LightBurn. It's been a joy.
RB
I'm not usually one to advocate buying things on Amazon, much less using filters, but in this particular case your eyesight is on the line. Unless you know a dealer of the following products that you personally trust, buy on Amazon and sort by "Avg Customer Review". And for the love of God, do your due diligence and take everything you hear about these things with a grain of salt.
First of all, the fireproof fibreglass enclosures generally work fine, but don't trust their tinted plastic windows to protect your eyes. The best practice with these things is to cultivate a habit of always, ALWAYS putting on your goggles before you ever enter the laser room.
If other adults have access to the room it's in, hang a couple pairs on the door with a warning sign to never enter without goggles. Make sure they know the rules.
Children should never, under any circumstance, enter a room containing a diode laser.
If your diode laser came with green goggles, those are almost certainly not good enough. Even if it was an expensive kit you bought. They're still the wrong ones. Look for ones with orange lenses that have video showing their lenses smoking/burning when the laser is pointed at them. And even then, make sure you have an enclosure with orange/brown tinted windows. Consider both proper goggles and the tinted window to be the absolute bare minimum in terms of eye safety.
If you bought a fibreglass enclosure and it came with a fan, it's probably too weak to do the job it needs to do. Get an inline fan that's marketed for growing weed. The diameter of the inlet and outlet ports should be smaller than that of the area within which the fan spins. The ones shaped like a can of beans almost certainly aren't going to be up to the job.
If your enclosure's design / instructions "require" the installation of a computer fan between the enclosure and the ducting adapter, you should ignore them and bolt the adapter right onto the the enclosure.
The general idea for exhausting your fumes is Enclosure->Ducting->Fan->Ducting->Exhaust Port. The exhaust port should vent outside of the building. If you own, drill baby drill and attach a permanent pest-proof vent out of which you will vent the exhaust. Otherwise buy one of the window ones.
On the subject of fans, because these enclosures are so small, make sure you buy a fan speed controller specifically designed for inline fans unless you spec out the CFM properly. You need a proper one because running large inline fans below a certain speed threshold will damage them, but on the other side of the coin, an overpowered fan is a waste of electricity at best and a safety hazard at worst. And an underpowered fan is effectively useless.
My final note for now is that there is, in fact, a method to the madness of the design of the enclosures with no bottom. Any fan worth its salt will be airtight enough to use suction to hold your enclosure down on the tabletop even with its intake window(s) open. This is a good thing - a fully enclosed fibreglass box would not allow sufficient air movement to vent fumes.
There is so, so much more to it, but in terms of safety logistics, I think that's most of the important points.
As for the enclosure, I'm going to do a whole separate section on enclosures this is more or less a placeholder, I'm still waiting on a sheet of 2C04 Acrylic to use as the window (the transparent piece in there right now is temporary). Good point about the glasses, the ones that come with the cutters usually royally suck.
You will have to hack some old mouse driver code to interface and determine which USB mouse input(s) are of interest.
It's a kludge that saved me time over a long three day weekend with no shops open years back when I was putting together a laser scanner project.
Eventually we had a proper stepper moter, for proof of concept it was an "uncontrolled" motor with a mouse scroll wheel counting clicks for rough "good enough" position feedback.
It was an Aha! moment for me when I looked a crate with old mice - they have rolling wheels and click buttons with plenty of sample drivers for counting wheel turns, <onclick> <clickrelease> events, etc.
Ain't pretty - but it works until a better version comes along.
...For everything?
>Unless you know a dealer of the following products that you personally trust, buy on Amazon and sort by "Avg Customer Review"
The 'following products" were inline fans and goggles and enclosures. And I stand by that.
In terms of primary hardware I agree if you have a reliable manufacturer. I avoided saying "Buy a Falcon2 (22w minimum) from Creality because almost everything else is overpriced or shit" because I didn't want to ruffle feathers even though it's true.