But I may have been a little overachieving.

I've got one of these which I picked up off ebay about three years ago for only 200 pounds, in a non-working state. It was working perfectly about an hour after being unboxed (a freaking HUGE box,as well, it was absolutely enormous), as the fault was merely a cheap and underspecced 12v transformer in the power supply.

All I had to do to make it actually useful was take it completely to pieces, remachine all the mechanical parts in the XY mechanism so they fitted correctly and ran smoothly, rewire it to make it safe, rebuild it, remove all the drive electronics other than the EHT power supply and replace them with something useful, rewrite the firmware to drive the mechanism, and align it correctly. Oh yes, and machine up a new lens holder with an air feed, add said air feed, add an adjustable bed, and align that. Easy.

It was about four days solid, but it was well worth it, as the thing works amazingly well and gets used several times a week. While it will only cut non-metallic things, there are a surprisingly large number of projects where either wood or acrylic are the right material for the job. It's an absolute godsend for model aircraft work, for example, and all my electronic prototypes end up in nice custom acrylic cases

But, after a while, of course, the old problem sets in.

It's not big enough.

It's not fast enough.

It won't cut thick enough material.

The usual complaints

So I designed and began building a bigger, faster, more powerful one. I may have become slightly carried away...



Now that it's nearly finished, I'm looking at it and thinking, "Ummm..."

I'm rather pleased, overall. It was designed in such a way that the grid bed can be removed so a standard 8 x 4 plywood sheet can be slid in and cut up in just under 600mm tall pieces. The cutting area is 1245x595mm which is pretty large, while it has a 100W CO2 laser tube in it, which is absolutely huge. The tube is 1.7 metres long!

I designed the entire thing in CAD, then had all the aluminium extrusion parts cut to order. Everything just bolted together in a very pleasingly accurate manner. Most of the fiddly bits are made out of 5mm acrylic, which is a surprisingly structural material as long as it's not bent too much. It doesn't like that.

Amusingly, laser cutters self-replicate. I made very extensive use of the small one to make the large one. Especially for things like very nice control panels.




The laser is designed as a completely independent intelligent peripheral, the idea being I could fit a smaller one if necessary. In fact, I designed it around a 50W tube but the 100W one came up at a silly price during the later assembly stages and I couldn't avoid buying it It did increase the cost of the project, as I then had to design a new housing for it, and get new mirrors and a power supply as well, but I think it was worth it. I can always sell the 50W one again.

It's entirely my own design, to meet a specific requirement, but I will admit that seeing it fully assembled it's slightly larger than I pictured...

On the other hand, it works, it's cost less than 20% of how much a really cheap commercial one that size would, and I've added a lot of things I wanted that I haven't seen on other ones. Plus it was a lot of fun building it. Now I have to figure out where it will live, I need my living room back!

pca

I'm particularly pleased with the self focussing head I designed. It's still slightly unreliable, but it's easy to make major upgrades just by cutting new pieces and bolting them on.

You just need to add a small segment of G-Code to the beginning of the job file and it finds the surface, then backs off to the rght focus distance, ensuring a perfect cut every time. In theory.





pca

Speechless.

I can only think of about a thousand projects that Thing would be useful for here.

Any chance of seeing it in person, next time we're over (which might not be for another couple of years)?

Of course. When you're next around, just let me know.

Patrick --

You are beyond amazing. The time I got to spend with you at the Amersfoort empeg meet in 2006 was the highlight of my trip, indeed one of the highlights of my whole life.

I still tell people of the 20-liter bottle filled with magnesium shavings...

Did your solar-powered refrigerator idea you discussed with me ever come about?

tanstaafl.

Now that you've got a shiny new laser cutter, what do you do with the old one? Convert it to a water cutter? That would deal with metal, glass, and all the other things that lasers can't cut.

It looks like you may have some problems with your fume extraction... And with it being a completely open construction, it's not very safe, but I guess you know that already.

Amazing, as always.

Wow. Impressive.

Unbelievable! I love it!

Slightly more then a "thing"...

Love this board!

-jk

And I was proud of myself for learning the word "tocino" today.

Thanks for the self-esteem boost ya steenkin' overachiever.

Thanks. A little overstated, but thanks

I've reisited the idea a few times over the years but haven't so far done much about it. I should, really.

pca

I'd love a water jet cutter, but they're non-trivial to build. The pump is the main issue, to make 30000+ psi, which is about the minimum needed to cut useful thicknesses of metal at a sensible speed, is both very complex and takes a remarkably large amount of energy. Some commercial ones using 60000 psi consume more than fifty horsepower!

A plasma cutter would be much easier, and in fact a friend is interested in me building a CNC plasma table for him based on my laser cutter design all embiggened, like.

The small cutter will, when redundant, go to another friend, who's looking forward to rehoming it.

pca

It does slightly fill the room with smoke...

There's a fume hood next on the design, with added cat-bisection-prevention skills, but I haven't made it yet. You have to remember to keep body parts you value out of the beam at the moment.

Mind you, it makes remembering this very easy, once you've been bitten the first time Pavlovian conditioning to extreme pain and the smell of burning flesh is very fast-acting...

pca

Bah, just double down on the laser.
http://www.coherent.com/Applications/index.cfm?fuseaction=Forms.page&PageID=292

I was also thinking about the danger of reflections of the laser beam, especially with 100W tube and the beam being IR. You have probably heard the "famous" warning from laser operators: "Don't look into laser beam with remaining eye"...
I built a buildlog.net 2.x laser cutter just after the empeg meet in 2011. Mine's only "40W", though. I had the Misumi extrusions sent to the hotel. Saved me from the VAT and some shipping charges...

Oddly enough, I'm not too worried about eye safety, from the normal laser viewpoint at least. At 10.6 microns the beam is an eye hazard more along the lines of a sharp stick rather than a visible laser. By the time it gets to your retina, it's boiled everything else in the way... Organic matter, water, things like that, are completely opaque at CO2 wavelengths.

It won't reflect off anything other than metallic surfaces and if that happens after the lens, the divergence is so large that a metre away you just get a warm face. 100W is a lot focussed to a few microns across but not very significant when it's a few centimetres across instead.

If you managed to get a good reflection without the lens in the way, at close range it could be nasty, but goggles would have no real use, it would go through them instantly, as would be the effect with the normal transparent acrylic lids even the commercial ones have. Those are tinted acrylic more to reduce the light from some materials being cut (glass reinforced plastic is amazing, it's like a tiny carbon arc torch and lights up the whole room) than to prevent the beam getting out and running around the place.

It's nothing to be disrespectful of, very true, but it's dangerous in a way that's quite unlike visible light or near IR lasers. Those are a definite eye hazard at significant ranges with any real power behind them. A CO2 laser is more likely to either electrocute you, or badly burn you along the lines of a gas torch, than cause eye damage in the way you might think when you hear 'laser'.

Some of the little DIY laser engravers I've seen that use high powered bluray violet lasers, a couple of watts at 445nm, on the other hand, terrify me from that aspect It may not sound like much, but that wavelength is a particularly bad one. Not only is it very close to the wavelength that the lens in the eye can focus to the smallest possible spot, it's also one that the human blink reflex doesn't really respond to AND almost the exact right frequency for maximum absorbance by haemoglobin, so it focusses down to a tiny spot, boils the blood, and blows holes in your retina far larger than seems reasonable... Yuck.

I have a couple of laser diodes at that wavelength and power. I ALWAYS wear the relevant safety goggles when using them even at very low power. At 2W just the diffuse reflection off the wall can be be more than enough to cause permanent eye damage. I've seen some pretty dangerous looking applications for them from people who don't seem to quite understand how hazardous they really are.

In the longer term, though, yes, there will be a cover.

A 40W laser is more than enough to be very useful, my little benchtop one is that class, although measuring the actual power shows it's more like 32W at maximum current, and even there the beam quality goes down the toilet if you run more than about 25W or so. You get a much cleaner cut at lower power rather than winding it all the way up to 11. The critical thing for the best results is to keep the tube cool. Ideally it wants to be around 10 degrees C or so, which needs an actual refrigerated chiller rather than the fan cooled heat exchanger that a lot of applications use. By the time it hits 25 degress the beam is getting ropy, certainly on the small ones.

They're damn useful and good fun, laser cutters

pca

I love the water jet here at work. I've used it to cut transparent armor into something a little more mobile than the test specimen was. Impressive what that thing can do.