Hacker News Reader

Comment by mft_ | Hacker News Reader

CNC would be an obvious implementation.

At the moment, there are expensive-but-affordable home CNC laser cutters, typically for a small number of thousand EUR/USD. The more powerful ones can do a very neat job cutting (up to a few mm of) plywood. There are also CNC plasma cutters, which do a good but slightly rough job of cutting sheet metal, and are relatuvely large and complex beasts. I guess a highly-powerful laser, of the type envisioned, would offer the best of all worlds: relatively neat and quick cutting of all materials on the same compact machine.

They might also replace handheld plasma cutters (and welders?) too.

View on HN

Diode based lasers have driven the cost to laser cut plywood down to affordable levels (~$200 for a creality/comgrow/chinabrand 5w laser). I just bought two of them off ebay as "customer returned" for $75 dollars a piece. they work great on the 1/8in plywood and 3/8in foam i've been cutting. Haven't tried 1/4in ply yet but I bet going slower or multi pass and it will do it.

Edit: It easily cut 1/4 ply (used 2 passes, but judging by the burn marks behind it I only need one). And that's without air assist to clear to the smoke which would help it cut deeper.

What is this genre of machine called, just a laser cutter? I would love to play with this

Yes, laser cutter/engraver.

Look for "diode laser cnc". If you search for "laser cutter" or "engraver" the results get mixed in with all kinds of larger machines.

The world of home laser apparati is kinda wild.

These are typically called "laser engraver" when you search for them but they advertise cutting features and cut well. 99% of them have a 5w laser diode, there are 10w and 20w models which just combine several 5w diodes somehow. Each one seems to double the price.

Searching for Comgrow, Creality Falcon, Atomstack, or Sculpfun laser engraver will get you pretty far.

Edit: I should add the more dishonest chinese sellers will advertise "20w or 40w laser engraver" and what they mean is the entire machine consumes 40w with a 5w optical output. Dont be fooled.

To my knowledge, you can't really use a laser cutter interchangeably on different materials. Metal cutting is done with fiber lasers, which have very small beam sizes and have a wavelength of about 1 micrometer. However, you can't use them reliably to cut wood, because they penetrate much deeper into it and can burn material below the surface before the surface has vaporized. It also is highly variable in how much gets absorbed, so engraving does not produce consistent results either.

On the other hand, wood cutting is done with CO2 lasers which have a significantly longer wavelength of around 10 micrometers. This wavelength is absorbed very well by wood and most plastics, but is mostly reflected by metals. Additionally, the longer wavelength means that it cannot be focused to as small of a point, which reduces the maximum power.

Chip lasers would still be bound to the same wavelength limitations, so you couldn't cut both materials with the same laser. What you could do, though, is have a machine with two lasers - especially if they are very compact - and select which one to use depending on what material needs to be cut.

Bit of a tangent, but you might have better luck with hardwood vs. plywood. The glue in plywood makes it more difficult for CO2 lasers to cut through. I was super surprised when someone at work mentioned they were able to blow through some hardwood in a single pass but had a struggle to get through plywood.

Does the heating from the laser cause any softening of the glue/weakening/delamination of the layers?

Some types of glue absorb a lot of the laser energy. There are dedicated plywood optimized for laser cutting https://n-e-r-v-o-u-s.com/blog/?p=6042

Yeah, my larger point is that there are already plenty of ways to cut metal in a home workshop.

I don't see how a laser would be an improvement on any of those, unless the goal is to CNC with extremely tight tolerances, but even then... it seems unlikely that you'll be CNCing blocks of metal, more likely just 2D cuts from sheets of metal, which is pretty limiting.

It would certainly be fun for some stuff, but I think the danger level of a super high power laser detracts from the fun.

More powerful cutting lasers would definitely be great for industrial use cases.

You're right that such things already exist; I think it would offer two incremental improvements:

* for wood, faster and/or thicker cutting, vs. existing CNC laser cutters

* for sheet metal, neater/cleaner cutting (i.e. cleaner cuts, higher tolerances, less subsequent prep-work needed) perhaps in a smaller neater machine, vs. existing CNC plasma cutters.

Especially within the context of a CNC machine, I wouldn't be overly concerned about safety - all of the more powerful CNC laser cutters I'm aware of already come with an exclosure - both for laser safety, and to constrain smoke (before it's vented safely).

The precision of a laser cutter would open up a lot of possibilities. Particularly making things that slot together with tabs - like fabbing my own welding squares and fixtures where a cnc plasma cutter would leave too rough an edge to have them slot together accurately.

Can't you buy a CNC mill/router that can cut metal more precisely than a CNC plasma cutter?

Completely different processes for completely different things.

Yes, and a laser cutter is also a completely different process for completely different things... yet you can still do some of the same things, and a CNC mill would be more appropriate for smooth cuts than a CNC plasma cutter.

Not cheaply, which was part of the OP's post.

Yes, for relatively cheaply. I’m not talking about a 5-axis CNC mill, and I’m not saying it’ll be fast. But a laser cutter is not fast either, and even if lasers get more powerful… a really powerful one is unlikely to be “cheap”.

Of course it depends on what you're doing, and what you're comparing to, but in my experience, laser cutting is the fastest option for hobby-level fabrication.

Tormach metal CNCs are $10K+ and take up a lot of floorspace.

A lot of people also cut sheet metal which a CNC tends to be terrible at.

We're talking hobbyist grade stuff here. People mount router bits on $400 CNCs and cut metal all the time.

Not $10k: https://youtu.be/w26DHMccicE?t=637

Even though it's cheap, the cuts still look pretty smooth and precise. I can't speak to the safety, as I would hope a $10k CNC would have more safety features.

They cut aluminum. Generally not well.

This part is actually a typical good result in spite of how bad it is: https://youtu.be/w26DHMccicE?t=731

Deflection is bad. Repeatability is poor. etc.

If you put even mild steel on that, that machine will have no hope.

Okay, but if you’re expecting a magical new diode laser to cut steel any time soon… good luck. That’s what most of this discussion is about. I think starting with a cheap CNC is more likely to work out.

o_O?

The article literally has a video of the laser actually cutting stainless steel (aka the Devil's chewing gum). The title says "melt steel". That was the practically the whole point of making these kinds of laser.

Video link: https://youtu.be/SFXmFNTviRI

Yes... but you can't buy it. It's in a research lab. And even once it goes into production, what are the odds that it's going to be affordable? They can probably sell every laser they can produce at a very high price for a long time before supply catches up to demand, even though this is supposed to be easy to manufacture.

I'm just extremely skeptical of a steel-cutting laser mill being cheaper than a $10k CNC any time soon. Hardware is hard. Semiconductors are even harder.

As far as I can see, the article provides no indication of when they even hope to bring this product to market, which is never a good sign.

https://xkcd.com/678/

I would love to be wrong.

And really, that video is unsatisfying. They show a mark on the steel, but -- as far as I saw -- they never even show any steel piece that was cut out by the laser. Maybe the steel melts at the very surface... but it may not be possible to cut through a piece of steel unless it is thinner than a piece of paper? We have so little real world information on this laser.

Actually, wow... the plot thickens. I missed this in my initial read of the article:

> We even used it to cut through steel. As the bright, beautiful beam carved a disc out of a metal plate 100 μm thick, our entire lab huddled around, watching in amazement.

So... it can cut steel! As long as the steel is 100 μm thick. I think that is literally about the thickness of a piece of paper.

This newfound information does not weaken my skepticism about the hobbyist laser mill that can cut through (useful) pieces of steel coming to a garage near you any time soon, unfortunately.

You can't cut sharp inside corners using a cnc mill (round bits), as one would want for tabbed fixtures.

Most sheet good are too large to be placed on or moved around by a cnc mill table.

CNC milling is a slow process (unless you can drop six figures on one).

CNC mills take a lot longer to setup and program, and also require more skill to have a successful result (no chatter, not breaking bits, ramping into the cut on interior features).

Good CNC mills that can handle steel are massively heavy and large machines which makes transport and setup difficult for the home machinist.

I use a 120W laser cutter for practical, precise, CNC projects all the time. I use a lot of 1/4" acrylic because it's a good material for this class of machine, but it's not the best option, structurally. If I could do the same with 1/8" or 1/16" steel, I would likely switch to that for almost every project.

I love the idea of using a mill/router instead, but IMO the more complicated process is fundamentally more dangerous. If a reflected beam can conceivably pierce the enclosure though, hmmm...

Reply on news.ycombinator.com