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FrozenGate by Avery

Laser CNC, engraving works, cutting doable?

That's cool. I'm in the automation business, more on the software side but I developed some hardware that has started selling real nicely now. I'm quite enjoying doing the hardware after about a decade of software only. I was going to use the CNC to engrave the serial numbers on the cases but these things sell too fast, it would take too much time. So now it's back to hobby purposes.

The CNC works nicely, not as fancy as some of the all metal builds out there but it can hold it's own.

I'll probably order a 445nm diode from DTR soon. :) Darn it LPF, I can see this becoming addictive.
 





altera said:
820mW that's not bad. What diode was that?

Anyway after some false starts I finally have the 405nm laser cutter up and running. I've been able to cut through some thin plastic. Thicker plastic more or less melts through. I think I might have to look into combining two beams for that.

I've made a quick video showing the laser making a (PCB/SMT) stencil in some paper.

YouTube - Laser 530 paper stencil

I also tried this on some clear packaging plastic and the laser cuts that no problem. So I have good hope I'll be able to cut my own SMT stencils from now on.
Click to expand...

Impressive DIY CNC Laser Stencil cutter....

and thanks for sharing...:gj:

Jerry
 
I've been experimenting a bit with the 445nm diode and as some of you guys have suggested the dot is certainly larger. Sadly it appears that the dot is so much larger that the power output per square inch is much lower. The 405 does much better due to it's focus no doubt.

I've ordered a 445 lens from Jayrob to see if that can help any but at this point I'm not too hopeful. Yes the 445 is powerful but it can't deliver that power into a small enough dot. I'll let you know what I find when the new lens comes in.

The 405 is also able to cut transparent plastic like overhead sheets, the 445 does nearly nothing to them. That's a bit of a disappointment.
 
The 445 needs to be closer to the material your cutting. But the issues with transparent stuff will likely still be there though.
 
The distance to the material will make all the difference. I find it hard to believe if not impossible that your 1000mA 445nm doesnt burn as good as the estimated 225mW 405nm....unless these original specs were way off. Your talking 4 times the power! and it will focus to a pin point with a regular glass lens if the distance is short.
 
The material's reactivity to the wavelength matters a lot. even at close range I can see 445 sucking at transparent stuff. Most plastics however are highly UV absorbant, so 405 will work better for any kind of plastic, unless it's black, in which case it shouldn't matter much.
 
Warning: some back of envelope stuff here. Not trying to start a flame-war just putting down some estimates.

I was unable to focus the 445nm to a pinpoint as small as the 405nm. If I had to estimate it would be 0.4 - 0.6mm 'dot' for the 445nm vs a 0.1 - 0.2mm pin for the 405nm. Let's run with that:

405nm dot has a surface area of about 0.13mm^2 (using 0.2mm diameter)
445nm dot has a surface area of about 0.79mm^2 (using 0.5mm diameter)

Assume the 405nm (200mA) puts out at 225mW
Assume the 445nm (700mA) puts out 500mW

405nm delivers 225mW/0.13mm^2 = 1730mW / mm^2
445nm delivers 500mW/0.79mm^2 = 633mW / mm^2

On top of that I think qumefox is probably right on the absorption. Looking at mylar/PET (PDF) it appears that plastic absorbs more light as the wavelength goes down. Favoring the 405nm.

The last point only being valid for transparent films of course. Black plastic will melt just great with the 445nm as long as you don't need as fine a cut as the 405nm can offer.

So unless I can get the dot size down with the better lens the 445nm will have a hard time competing with the 405nm. This is consistent with my observations on the CNC so far.
 
Well those calculations assume your dot size is correct. Any small variation in the actual dot size will change those number dramatically. I was also assuming your 445nm was set at 1000mA which usually gives about 1000mW with a good lens. Also keep in mind with a good heatsink you could run the 445nm at 1500mW and still get good life.
 
Of course, hence estimates. I'll report back when I get the new lens. I assume people are interested in hearing this.
 
Any update on this? PS, which city do you live in, altera? I'm from SoCal and building a DIY laser cutter/engraver right now as well.
 
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