Rapid Prototyping machine laser

I'm an electrical engineer currently trying to design a DIY rapid prototyping machine. It will be my own version of a Laminated Object Manufacturing(LOM) machine. Basically it's an xy laser plotter that has a table moving on the z axis. It cuts profiles out of paper and builds objects by gluing the paper together layer by layer. I'm looking to build my own laser assembly that will be able to cut kraft paper at a decent speed. An example of kraft paper can be seen here uline.com/BL_1951/Kraft-Paper-Rolls it's the stuff that paper bags and package stuffing material is made out of. I don't really want to spend hundreds on/build a CO2 laser so I'm really hoping i can just use a diode. Possibly more than 1 I guess going through a collimating lens and setting my cut point at the optimal convergence point.

So, after lurking this site, I've come to the conclusion that I'll need to build a "lab" laser, but I have a few questions. The laser doesn't need to be super precise or have a small beam width because I won't be cutting anything really small or detailed, nothing like some of the xy plotters I've seen on youtube.

1. Is the noisy DC voltage coming out of a "wall wart" power supply going to affect the LD driver or laser?
2. What wavelength/color would you recommend for my application and where do I get it?
3. I'm thinking the zbolt heatsink/housing is gonna be my best choice, but what about collimating lens?
4. I'm an electrical engineer so building my own driver is no problem, what current range should I be looking at?

Thanks

Chaston

I would think that it will require a few watts to get things moving at a decent speed.  The cheapest solution would most likely be a 3-4W cmount diode. There were some on ebay a while back costing anywhere between 100-200$.

They are 980nm, I have one mounted on a aluminum heatsink, all it requires is a 4amp+ power supply at 10-12vdc.

If you wold like to buy the one I have, it is brand spanking new with zero minuts on the diode as I still havent bought the proper goggles for the wavelength. Its been a backburner project sitting in a box on a shelf.

The driver is partially finished, just needs the proper resistor to set the current of an LM 350 to 3-4amps. These diodes have been run at 4W but will have a better life at 3W maybe a tad higher.

PM me if interested

I'll keep that in mind, but would it be cheaper to run 2 or 3 16x dvd burner diodes through a collimating lens? Would anybody be willing to use their collection of lasers to see how much power is required to cut a paper bag? I would really appreciate it.

thanks
Chaston

It might be possible to merge multiple laser diode outputs into a single beam but i would think you'll need to collomate each one to a beam, merge them using some fancy optics (see the thread on white lasers for an example) then another lens to focus the output to a point.

This is just guess work on my part but i think the theory is sound.

*edit* Thinking about it some more, unless you have some really fancy equipment the 2 or more beams won't be properly aligned and may cancel each other out resulting in a dimmer beam? Hopefully someone with more knowledge can clarify this.

You should also consider the fact that most visible light lasers do not cut paper well... I recommend a CO2 laser since they lase in the far infrared spectrum and are absorbed by most materials better. "Heurrsciences" is selling a few RF excited CO2 lasers in the B/S/T section at a very modest price...

Get somebody with a 6x violet on the forum to test it for your purpose: have them try and cut a paper grocery bag (or whatever kind of paper peopl are likely to have at home that will match what you have), it may do it. Not fast, but it may handle it ok for what you want. And a 5.6mm can diode will be MUCH easier to mount on an xy. Very small, nice and modular without having to worry about the big RF CO2 or bigger high-powered IR c-mount diodes that are harder to deal with. Not certain how well it will work, but it should be easy to get someone who owns such a laser to try it for you.

I tried to cut paper with red diodes but it doesn't really work. You can cut black paper (100 grams) but it cuts very slow and leaves burnt edges. Thinner paper will be easier. But I think it has to be black. I tried white paper, but it only burns when the spot hits a print on it. Just white paper won't burn. I used a dilda laser with an extra focusing lens. I want to do 1 final experiment with a DVD diode laser and a pulsed current source. I hope that I can get a bit more power into the spot by pulsing. But to be honest, I don't think it will work with a (cheap) 200mW laser. More power means more money. I'll go for a CO2 laser, this will make burning so much easier. But mechanics will be more complicated.
I found a laser setup, but unfortunately I am not allowed to post links yet. It has a 1W laser, but this is expensive. You can buy a small CO2 laser which will burn a lot easier.

If you are set on 5.6mm diodes, a 6x 405nm from the GGW sled, or a 500mW 808 is probably your best bet. If that doesnt work and you want to keep it simple, c-mount is the way to go in my opinion.

I have played with c-mounts and at 1 watt  they eat through thin brown cardboard. At 4 watts, you should have no problem, in fact it may be overkill, as would the idea of glass tubes and fiber op.



@pullbangdead, what exactly is difficult about a c-mount setup?

It's not that difficult, it's just all relative.  If a 6x violet would do the job, then a 6x in an Aixiz is cheaper and easier to handle and work with.  Neither is particularly difficult, but a 5.6mm can in an Aixiz is extremely easy to mount anywhere, in basically any set-up because it's just so nice/small/modular and such.  That little tube is just so convenient and easy to work with, and very readily available (seems like everybody has 10 of the things laying around already).

And, you'd have a violet laser to play with when not using it for the cutting tool.

Just curious, how much power does a 6x violet puts out?

A 6x will not cut fast enough. I tried one on my cnc and it had to move a little slower then a snail could crawl in order to etch light colored wood. I tried black construction paper and although I could speed it up, it was still way slower then a practical application called for. I would be looking at 1 watt and above to get any speeds.

You need to realize that what qualifies as a "powerful" diode laser here can barely light (black-colored) matches or cut through black electrical tape, let alone cut through paper with great ease. These diode lasers you see mentioned on this site are generally < 500mW--good for seeing a pretty beam, poor for much else. Real cutting lasers, on the other hand, are on the order of tens to hundreds of watts, and though without the pretty beam.

It's a nice idea you have, but you're not going to go anywhere with it unless you're willing to invest in the proper equipment--and no, it doesn't come cheap. Perhaps invest the time into designing a DIY pick-and-place machine or a DIY CNC mill. It has about the same requirements as the laser-prototyper. You can also try using a heated wire instead of a laser for cutting.

Bionic-Badger said:

It's a nice idea you have, but you're not going to go anywhere with it unless you're willing to invest in the proper equipment--and no, it doesn't come cheap.  Perhaps invest the time into designing a DIY pick-and-place machine or a DIY CNC mill.  It has about the same requirements as the laser-prototyper.  You can also try using a heated wire instead of a laser for cutting.

Click to expand...

The reprap might be interesting as a rapid prototyper.
I have retrofitted a millingmachine and this works pretty good. But, it is a cheap low quality hobby machine. So, accuracy and power are limited. I guess it will be exactly the same with whatever lasersystem you built. You just get what you pay for.

If your plotter xy stage is capable of moving a fold mirror and a lens around, CO2 is a good choice for cutting stuff. 10.6 micron radiation is totally absorbed by most stuff including paper. The DVD lasers are way too wimpy to cut anything fast. Paper absorbs 405nm bluray much better than the reds, but still very slow going. I tried one running at around 100 mw on white paper. It cuts, but at a slug's pace, and the reflected energy is dangerous. A 650nm red running 250 mw won't touch white paper unless there is a dark spot to get it going.  

I used to design flowing gas CO2 lasers back in the early 80's, multiple kilowatts of major burning mayhem. We used 125 watts to scribe ceramic and such. A 50 watt CO2 tube properly focused will cut paper and thin cardboard really fast, several 10's of inches per second easily. I am sure 10 watts would work, only a bit more slowly. Of couse you will need a zinc selenide or germanium lens to transmit and focus the deep IR. You also need to be careful not to catch your paper on fire - maybe an argon cover gas or something. You will probably want a pressurized cover gas cone over your lens to keep smoke from depositing on it anyway.

Another benefit of CO2 is that 10.6 micron radiation cannot be focused on your retina - it doesn't penetrate the eye at all and is completely absorbed by simple glasses. You can get surface burning, but it is almost impossible to be blinded by the scattered radiation - just stay out of the beam and back up if it get too hot.

A higher power C-mount IR diode or a yag would work too, but be careful with the reflected IR, it focuses perfectly on your retina. Because you can't see it they are much more dangerous than visible lasers. It will instantly blind you permanently.

I am working on an XY plotter build at the moment, I was originally going for a CO2 laser but am now going to try some IR options...thanks to Wannaburn.
I have attached below my first idea on beam steering, which is similar to what Achro describes only I want to turn the beam upwards for various reasons.... In fact I have 2 jobs to do with this, one is to engrave on wood (beam directected upward) and cutting out plastic templates (beam directed downwards) so I am looking at a rotatable final lens assembly.


@ GemaRastem and Bigengineer I will watch your projects with interest and pick your brains on software to drive this as it will be taking me places I have never been

Regards rog8811

Hey rog is that not a job for fibre? I dont have seen a original laser plotter.
I think its difficult with mirrors. Because the laser have to aim at the first lens in the picture, it require alot more moving parts to build with.


daniel