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Engraving with laser diode: need some help

thieuv

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Hello,

for a school project we wan't to engrave fabric like jeans / fleece / cotton.
We would like to engrave some custom logo's on jeans or t-shirts.

Now we need some help with selecting a laser diode:
We have found the following: 2Watt laserdiode or this one.

Does someone has experience with engraving with laser diodes? Is it possible with these laser? What do you recommend?

Kindest regards,

Mathieu
 

Cyparagon

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That's a bad idea for several reasons. Here are the three I can think of at the moment.

1) You will have a difficult time getting the power right and usually end up cutting through the material since it is thin and weak.
2) Fabric can catch fire at these powers.
3) You will weaken the fabric to the point of rendering it useless for clothing.
 

thieuv

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Yes, we thought so, but that's a risk we wan't to take.

For the moment we are looking for a laser who can engrave stuff.

Mathieu
 

ZRaffleticket

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^ what cy said

Just because you see engraved fabrics for sale doesn't mean they're necessarily easy to make yourself. High precision equipment is necessary.

Plus I do believe pulsed lasers are used to engrave cloth as to not penetrate the fabric...
 
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thieuv

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Well, okay I understand, but we want to find a laserdiode who is capable of engraving many materials. Maybe jeans or other fabric... Does somebody know which laser is good for this?
 
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What type of school? I'm guessing college? I don't feel comfortable because eye safety is a top priority. You know laser safety yes? Not to be a jerk but you also spelt a couple things wrong. You spelt want, wan't. Personally I would recommend searching for other methods. With lasers you risk: blinding people, burning people, and staring a fire. Add on that the diodes required are probably a bit pricey an if you fail all the money is gone
 

thieuv

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We are studying at the university of Gent, Belgium. Sorry for my bad writing.

But however we are aware of the risks. We have already safety glasses at our departement. The only thing missing is some experience for choosing the right laser diode.

We know they are pricey, that's why we need to be sure that it is a good one for our appliance.

I hoped to find an answer on this forum...
 
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Sounds good. Z and cy are some of the best and so I'd go with their word. Sorry but my help stretches from wavelength and power to basic DPSS but no engraving cloth. Now if you need help with soldering or drivers and such I can help there. Sorry I can't offer further assistance.
 

ZRaffleticket

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I just looked up standard procedures. I've seen both pulsed solid state lasers as well as CO2 lasers. Everything is extremely fast. It engraves a meter or so width instantaneously.


That gives you a good idea about what you're up against.

Now you want to use a laser diode.

You're going to get a VERY poor beam shape with the 445nm diodes. The only way you'd want to get around that is probably by focusing the laser (also compensating for the lesser power than the system I linked)

These diodes have poor beam shape vs CO2 and YAG lasers because of the way the light is emited. The diodes will emit a line --- vs the round dots the other two will produce.

The diodes have line shaped beams because there are two axes of divergence. The one diverges faster than the other.

Because you'll need to focus the laser, you must have the diode at a fixed distance from the fabric... meaning simply rotating from a distance back and forth will NOT work. You can thank the divergence of the diode. You won't get a small focal point from a distance.

The system you plan to make using one of these diodes would require the diode assembly to rapidly move across the fabric with high precision.

I don't know how to calculate the speed you'll need to do nor the focal distance you'd want...

______________
Bottom line

I think there better options than diodes for this project. Look into Nd:YAG lasers or CO2 lasers for this application, more specifically ones with modulation. The beam shape on those is not a hindrance. You'll need to point the laser at a mirror galvanometer in order to redirect the beam... bringing back the safety goggles... and more importantly a self-contained system.
 
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thieuv

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Okay, thanks for the explanation. But the goal of this project is DIY so it must be cheap. That's why we looked into laser diodes, because they are relatively cheap in comparison with CO2 lasers or YAG lasers.

We already thought of fixing the diode at fixed distance from the material. Also it was the idea to focus the laser with a lens.
If I understand it correctly, maybe it would be possible to engrave fabrics if we find the right speed, and pulsing speed for the laser?

Other application image etching: found on this forum.

This is possible with the suggested lasers?
 
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Yes, but not on fabric. That is only good on materials such as wood or plastic. For fabric, you either
need short high power pulses or a very fast moving high quality beam with tens of watts. You want to
scorch a tiny surface layer without heating through the fabric.

It would be either DPSS, maybe q-switched, or the aforementioned CO2 laser with a galvanometer(s).
Flashlamp pumped SS would probably get it done, but it would be much slower. Out of those, the only
"cheap" options would be the CO2 or flashlamp pumping, but galvos can get quite expensive. It might
be possible with a homemade galvo, but that is fraught with difficulties of its own. You still need
computer control to position the galvo.

Be sure to have plenty of fabric to burn because it will take some experimentation before
you get it right.
 

Spooky

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This is possible with the suggested lasers?
Johns software is very good, the methodology used in the case of two non-combined diodes isn't.(it basically doesn't work for a number of reasons unless the laws of physics have changed in the last 20 minutes)
I can do all the numbers for you but "cheap" for components won't happen once you figure in the cost of a gantry system / galvo steering and the software / pc to run it all.

Better option would be a 15-20 watt glass DC powered tube from China (a 400mm tube).

Be aware you are playing with a system in the case of a CO2 tube that doesn't promote a human blink reflex, by the time you realise something is wrong it WILL be too late.

I would suggest doing a LOT of reading before getting involved with CO2 tube or high power diodes.

cheers

Dave
 
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thieuv

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Hello, I have some questions about the following laser module: Nichia NDB7875
I can buy this with a driver, but then there is a limitations in duty-cycle. Or I can buy it without, then I can choose another driver with no limitations in duty-cycle? Our machine will have a fixed 12 V. Are there drivers you recommend? For this laser diode?

The lowcost laser driver with lm317 can't deliver enough current (max 1,5A). So maybe one of you created a good driver?

Thanks for the explanation! I have learned/readed already a lot on this forum.

Mathieu
 

DTR

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If you sink the IC of the X-drive driver just like you would have to do with a LM317 but with much less heat generation you can run the driver continuously. I can also offer to put leads between the diode and driver so you can conveniently mount it to your heatsink. It is pretty easy. Also this thread has a lot of good info on engraving with the 445nm diodes although I have not seen anyone trying to do it with fabric.
CNC Laser Engraving 8bit Shades of Grey 445nm
 

Trevor

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Because you'll need to focus the laser, you must have the diode at a fixed distance from the fabric... meaning simply rotating from a distance back and forth will NOT work.
An f-theta lens will correct that. But that doesn't make this any less silly to attempt with a laser diode... :p

Trevor
 




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