School project: Homebrew laser etcher. *UPDATE* November 15

So for my Embedded Systems Design class(always throws me off. ESD is ELECTROSTATIC DISCHARGE! HIDE YOUR ELECTRONICS!), we're supposed to choose and build a final project. I'd figured on a CNC machine of some sort, which would involve motor control, positional feedback, and serial bus communication(the demo boards can't do USB, and none of the labs thus far has involved bidirectional communication, so I'll learn quite a bit here). Trying to decide on whether to make a drawing machine or a 3D printer, I stumbled upon what I imagine is a rather ingenious idea.

Why not affix a burning-type laser to the head and use signals to turn the beam on and off? Drops off a lot of the mechanical aspects of print heads, marker actuators, or extrusion tips.

So I imagine I'll be running through one of Jayrob's tutorials and building my etch head using an old DVD burner. Since lasers are not my strong point, but they are the strong point of pretty much everyone else here(which is why I joined in the first place, even though the pointer for my dad isn't happening this year), I thought I'd ask for some advice.

I'm after a solution that's cheap, works, and can be built reasonably in a week or three. Project's due in about a month.

In exchange, I'll be sure to post build pics. No progress yet.

Brains: Atmel ATMega16L on an STK500 demo board
Motors: to be scavenged from scanners and printers in the broken pile at the local pawn shop.
Wiring: mostly from a supply of old Cat5 that the company I work for threw out back in March.(Dumpster diving is so profitable!)

Thanks in advance!


UPDATE 1: November 15, 2009
Purchased the first part of my build yesterday: an HP Scanjet 2200c, from the broken section of a local pawn shop.
$5 gets me one white cold-cathode light with self-contained starter board(only two pins lead from the bulb's igniter board to the scanner board. Looks like a +VCC and a Ground wire.), some sort of image capture component with lens and mirrors, a linear actuator mount, and what looks like one of these.
The label says Mototech S42T6-3001/11B0EB 301-0009, that datasheet looks like the closest match I'll find. Nice stepper motor. 5-pin control.

Never used a stepper motor before...

Re: School project: Homebrew laser etcher.

Laser etchers/markers use a CO2 laser coupled with a set of high precision galvos. Your "CNC approach" may work but it's going to be slow...

Re: School project: Homebrew laser etcher.

if you want a good microcontroller with usb communication, that runs off of a 9v battery with the uploaded code, i recommend arduino.($33 from makezine.com, at the makershed.)
you can get all the parts for a purple laser (i.e. a PHR-803t in a focusing module, and a micro-drive) for $40 from modwerx.com. all you would need is a little electronics experience.

Re: School project: Homebrew laser etcher.

What kind of etching/cutting do you want to accomplish with this?

If you want to etch dark, soft, or thin materials quickly, you can use either a high power infrared diode. They are pretty cheap for high powers.
If you want to burn a wider variety of surfaces more precisely and quickly, you can look into a high power violet diode (8x or 12x @ >300mW).

For cutting or faster etching of thin materials, you will need more than 1W output power. For this, a high power IR laser would be the most cost effective option.

I don't have experience with CNC machines or building them so others will be able to provide more help.

Sounds like a good project.

Re: School project: Homebrew laser etcher.

SOooooo --- what do you want to do? You can slowly burn a line into paper , wood or soft stuff with minimal power but demonstrate control.
Soooooo - put a BluRay into the head and move it over black paper and cut out stuff. Explain that you are using low power for safety reasons.
It's all in the show you know.

HMike

Re: School project: Homebrew laser etcher.

There is a thread here.. search CNC machine diy.. it shows another members cnc machine that he built, this could be adapted very easily with a laser pointer to etch and cut things. I'm actually doing the same thing atm! If you need any help, please pm me!

Also the software is free and easy to use. Try out mach3, mastercam... etc, they are what you are looking for! -Adrian

Re: School project: Homebrew laser etcher.

Hemlock_Mike said:

SOooooo --- what do you want to do? You can slowly burn a line into paper , wood or soft stuff with minimal power but demonstrate control.
Soooooo - put a BluRay into the head and move it over black paper and cut out stuff. Explain that you are using low power for safety reasons.
It's all in the show you know.

HMike

Click to expand...

I'm thinkin' roughly this, but clearly, I've come to the right place.

How effective it is isn't so important. It's a project for a microcontroller class. The controller itself isn't horribly important, I've got three to choose from already. I'll have to turn the STK500 back in after I finish the class, but if I want to continue with it, I can probably refit it to work with one of the other two that I get to keep.

Re: School project: Homebrew laser etcher.

Then for the laser, some IR module, labby style, can be ok, for you ?

O-like have some, and also in ebay, occasionally, can be found something similar.

The only problem can be the focusing, those "brick style" modules are not good for focusing at short distance (at least, if you don't find a lens for change the original one).

An alternative, can be the use of a "fiber coupled" 1 or 2 W, 808nm ..... focusing and assembly of the fiber can be more easy, in this way.

Anyway, i suggest you to not use wavelenghts longer than 808nm, for a simple reason ..... 808nm is still visible, also if very dim / dark red, so you can know immediately if the system is on and focused ..... where, instead, also if more far IR can be more efficent, is totally invisible, so you need a visible guide beam, and this involve a beam combiner, and so on.

Re: School project: Homebrew laser etcher.

You should try getting a blu-ray 6X diode. It will etch better. (www.0-like.com--Ê×Ò³)

But you will need some safety goggles. (Green Laser,Laser Beam Optics,Laser Safety Glasses : Dragon Lasers)
And since the lasers is gonna be running for a long time you will need a big heatsink, but it will probably be a bit heavy so I suggest to get a TEC and read Jayrob's tutorial in the tutorial's section.

Re: School project: Homebrew laser etcher.

Consulted my dad. He suggests I go for something that'll burn reasonably well, so I'm going to tear apart a DVD burner we have and if that's not good enough, I'll go ahead and spring for a Blue-Ray burner.

I was planning on enclosing the thing in dark glass for eye protection so I don't have to buy goggles for the whole class, but a pair of protective goggles for myself is probably just a good idea anyway.

Thanks for the heads-up on cooling. I'll be sure to give it a big heatsink and maybe a fan.

I'll probably buy the first scanner today.

Re: School project: Homebrew laser etcher.

The DVD burners will be a lot more powerful than the blu-ray ones, depending on what you're planning on burning (i.e. the absorption).

I've been meaning to try it myself, but another thing to try is to use the sled carriage inside the DVD burner to control the positioning of the laser. They're already mounted, very stable, well-built, and are controlled by a screw drive attached to a stepper motor so they have pretty decent control.

For showing a class, make sure you really do have enough protection for them. Smoked glass or something of that nature is not enough, especially since you'll be focusing the beam on a single point. Thicker transparent colored plastics in a color absorbing the laser wavelength you're using will be good. I remember seeing some nice dark blue or green transparent clipboards at office max for like $6 or something. Try bringing a laser pointer to the store and see if you can see any light through them, or very very little. They may be suitable.

Re: School project: Homebrew laser etcher.

i would suggest to stick to 405nm lasers. it absorbs so much better on almost any surface! my 100mW phr violet laser burns better than my 300mW long-open-can (LOC) diode. both focussed and unfocussed.
with lower outputpower, you have less problems with heat, and its somewhat less eye-dangerous.

its easier to protect against violet too.
for enclosing your setup:
lee theatralical gel-filters would be an option. "lee 010 medium yellow" blocks more than 99% of 405nm. still quite clear, you will easily see whats going on inside. maybe put that foil into frames, and clip these (with strong magnets?) to your setup when needed.
Lee Gel Sheet #010 Medium Yellow
(a random shop, look for a cheaper one, if you choose this way)

sure, this foil is in no way serious protection against worst-case-disasters. with a direct hit of 100mW of 405nm, the foil starts to deform after a second already. it wouldnt immediately melt, but wouldnt hold up against it too long. its more than enough to protect against reflections (from the melting target).
even a direct hit from the beam would be ok if you notice it. and you wouldnt operate this setup without watching it, right?

eyeprotection:
this is important when doing this kind of aligning/tuning/testing!
fortunately, 405nm is easy to protect against. there are several threads about those yellow sportsglasses, or bicycling-glasses, or glasses for seeing better at night when driving. i tested several of those. they all protect against a direct hit. they all hold up against more than a minute of direct radiation. the better of the tested ones block 405nm entirely. i only see the faint yellow glow. the "worst" still blocks so much, i only see a hint of violet. you would want to still see a bit of violet to be able to adjust stuff. when adjusting, you should operate the laser (whichever it will be!) barely over lasing-threshold. you could use a fluorescing target (big word for plain paper!) too.
your best bet for known-good googles (blu-ray only!) are these:
http://laserpointerforums.com/f64/yellow-goggles-blu-ray-blocking-43262.html

you could try to couple the laser (whichever) into a single fiber. at the busy end of the fiber, you only need a single lens. your focussed dot cant be smaller than the diameter of the fiber (-core) though, and you will lose power with coupling. could still be worth it, for a super-light head, instead of much more weight for the whole module. an aixiz module (maybe with a tiny fan) would be enough though. if you dont have to move the head too fast it should be sufficient.

okay, i totally lost track of what i wanted to say..

manuel

Re: School project: Homebrew laser etcher.

I bought the scanner, but I didn't buy the deputy.

Which is probably a good thing. Slavery's been outlawed here for ages.

Right, so diode selection...

Etch speed isn't important, so long as I don't occupy the entire class and/or blind anybody. I have currently a Memorex DVD/CD R/+RW drive, so I've got one IR and one Red diode I can test with.

Label says 2.4 X 8AA. Probably a 2.4x DVD burner, 20X CD burner or something like that.

Test and demonstration material will probably be the ream of construction paper I bought a decade ago and never used.(I had a reason! No, really!) What diode would likely give the best results: the CD writer, the DVD writer, or a Blu-Ray?

Project is due in about a month, so I can't spare more than two weeks for parts shipping. I'll probably build one of the home-made drivers I've seen elsewhere on the board using parts available in-lab(I'm a cheap bugger, I am!), but if it turns out well, I'll probably spring for a professionally-made one.

Re: School project: Homebrew laser etcher.

Bionic-Badger said:

I've been meaning to try it myself, but another thing to try is to use the sled carriage inside the DVD burner to control the positioning of the laser. They're already mounted, very stable, well-built, and are controlled by a screw drive attached to a stepper motor so they have pretty decent control.

Click to expand...

Sorry to say this, but this reduce your available power, and burnin capacity too.

Sleds are not built for power, they're built for precision and focusing spot diameter ..... this means that all the elements inside contribute to this, but also take away lot of power ..... just as example, the diaphragm alone (the little plate wit the hole in front of the diode) take away half of the light, in the purpose to obtain a round beam shape ..... the cube, lenses and so on, made another good part ..... if you use the sled as is, you're probably lucky if you get 1/3 of the total power produced from the diode ..... and this being optimists


BTW, a 2,4X DVD burner looks as a very low powered red diode .....

Re: School project: Homebrew laser etcher.

Correct me if I'm wrong, but don't laser etching machines utilize a pulsed laser ? I know they do for epidermis treatments, like tattoo removal, acne scar removal, etc. Anyone know the answer to this one ????? rob

Re: School project: Homebrew laser etcher.

Industrial etching machines usually uses CO2 lasers ..... and, as far as i know, most of them pulse the beam only cause they do the etching in scans, so they turn it on and off for make the figure / letters / whatever, like a printer do with ink and paper, not following the contour of the figure like with CNC machines.

There is some solutions that uses pulsed units, but for specific uses, not for common use.

Except for tattoo removal and aesthetical use, but this is due to the fact that you need to act "on surface" on the skin, and not in deep, and using continuous beams, you transfer too much heath and burn the skin.