Question about DIY engraving laser.

[Daid]

First, let me say, I love my eyesight, so whatever I will do I will get safety glasses before I start toying with lasers.

That out of the way. I'm a hacker, a builder. Someone who makes stuff. I'm not afraid to get my hands dirty. I'm also capable with electronics and computers.
Adding to that, I have a 3D printer. (this one to be exact). And my experience with lasers is limited to laser pointers to amuse cats.

Now, we (as 3D printer owners) are always looking to expand the capabilities of our machines. Some people are printing chocolate for example. But I want to see if adding an laser engraving capability is an option.

Now, I did research, but I'm still confused. Some results say I need at least 1000mW for any burn capabilities, but I've also seen sources say you need 200mW. And some sources just say "A DVD burner laser diode" with the right hacks.

Now, I have about 100 euro that I wanted to spend on this project, max. But if I go and look for lasers I quickly go over that price. But then I look at my local hardware shop, and a DVD burner is only 19 euro. I still would need a driver circuit, but that would only set me back ~5 euros or so. And an enclosure to hold the laser and lens... guess what, I can print those myself

So I have a few questions:

1. What rating should I be looking at for engraving (burning) wood? And I guess cutting paper would also work then? To make it clear, I have no intention to cut wood. That would need a 40W CO2 laser.
2. What would be cost effective? Getting good lasers, or to destroying a DVD burner? It feels silly that destroying a product can be cheaper then parts. But it has happened to me before with certain types of connectors.
3. What are good sources in Europe for laser (parts) and accessories? Glasses. Glasses. Glasses. And did I mention I want to buy safety glasses before I start to thinker? (Sorry, not ordering overseas, due to getting burned by shipping costs and taxes)

 

[Daid]

Not a lot of responses...

Anyhow, I did a whole lot of more reading. And the amount of scary stories is frighting. But first to answer my own questions:
1) 200mW can be enough for some burning, with the right focus and material. And if you take it slow.
2) Both o-like and lazerer seem to sell lasers that meet my price range and power requirement. In module form (not in pointer form). The 250mW red laser is 30 euro, which is only 10 euro more then a DVR writer. Add a driver and housing, and it's just as cost effective to buy an a full module. So no DVD salvaging.
3) See 2.


Now I'm wondering if the red blocking goggles from Lazerer are any good. They claim OD5, however, goggles with OD4 from survivallaser are twice as expensive. I wouldn't be needing goggles per say, because this laser will be mounted to point down, always. But reflections from a 250mW laser could damage eyes, and I rather not take chances.

(I'm also wondering why lasers come in round enclosures, a common fault seems to be a laser rolling away and shining at something it shouldn't have shined at)

 

[Sigurthr]

Glad to see you did some more reading!

I have the T-REX 650nm goggles as well as the Suvival Laser Eagle Pair OD4 High Frequency (190-540nm) goggles. The Eagle Pair ones are VASTLY superior.

The Eagle Pair will completely block a direct beam (of 405nm, 450nm, and 532nm), and it has been tested at over one watt.

The T-Rex still transmit a fairly decent amount of power from a direct hit (of 650nm), I would estimate 3-7mW of my 200mW gets through them. No LPM here though so all just estimate, but still, it does NOT completely block the beam. That being said I can burn / cut with 200mW comfortably with them on without getting after images or headache. The flash from my camera is much worse. I wouldn't trust them to protect from a direct hit though, not at all.

Keep in mind -what- you want to engrave. Plastic is one thing but wood absorbs 405nm better than any other wavelength from diodes. You can get a top-of-the-line 500mW+ 405nm module from DTR for $125. I know it is more expensive than that 250mW 650nm module you were looking at, but this will vastly out perform it.

Engraving takes a long time as well, so also invest in a very good heatsink and some thermal paste.

 

[Daid]

Glad to see you did some more reading!

Unlike some people I tend to do a LOT of research before I do something which might be a hazard. I also have near perfect eye sight, and I want to keep it that way

I have the T-REX 650nm goggles as well as the Suvival Laser Eagle Pair OD4 High Frequency (190-540nm) goggles. The Eagle Pair ones are VASTLY superior.

The Eagle Pair will completely block a direct beam (of 405nm, 450nm, and 532nm), and it has been tested at over one watt.

The T-Rex still transmit a fairly decent amount of power from a direct hit (of 650nm), I would estimate 3-7mW of my 200mW gets through them. No LPM here though so all just estimate, but still, it does NOT completely block the beam. That being said I can burn / cut with 200mW comfortably with them on without getting after images or headache. The flash from my camera is much worse. I wouldn't trust them to protect from a direct hit though, not at all.

That's a 96.5% reduction, no where near OD5. But somewhere between OD1 and OD2. Thanks, getting a product with false specs just supports giving off false specs. So I'm not getting those.

I'm not expecting to shine into my eyes. And reflections should all be diffuse, but you're never sure. For example, black plastic looks very dark, but usually has a shine to it. Which is a specular reflection, it might be less powerful then the beam itself, but I'm not taking chances.

Keep in mind -what- you want to engrave. Plastic is one thing but wood absorbs 405nm better than any other wavelength from diodes. You can get a top-of-the-line 500mW+ 405nm module from DTR for $125. I know it is more expensive than that 250mW 650nm module you were looking at, but this will vastly out perform it.

Interresting, I figured I use red because it had the most power for money. (Well, maybe IR has more, but I rather see the laser, then have an invisible blinding beam)
I'm not that comfortable to pay 125$ for a diode which I still have to assemble myself. But O-Type has a 90 euro 500mW laser which would do very well: Industrial 405nm 500mW laser module /Focusable/TTL [OL-405-500] - $119.99 : Zen Cart!, The Art of E-commerce which also seems to solve your next point with it's big ass heatsink+fan.
It's also in my 100euro budget, but not when I add glasses. Which is not a huge deal, because I would get double the power, and more power transfered to the wood. Not to mention TTL control which would be great, as I no longer have to hack the supply then.

Engraving takes a long time as well, so also invest in a very good heatsink and some thermal paste.

With heat being a real problem for the laser diodes (permanent damage) I'm surprised not to see more "Thermal resistance" specifications. Which is quite common in electronics to calculate heat sink requirements. I see the specs on some sites like survival lasers, but I was kinda expecting datasheets, as you get with electronic parts.

And the above mentioned red laser from lazerer specified a 45sec on, 30sec off cycle. So I figured I needed quite a bit of extra cooling for continues operation on that one. Another problem solved with the 405nm 500mW from o-type.

Now to hope the shipping costs won't kill me, and I get it trough customs. I'm in the Netherlands, which seems I am allowed to own a laser like this, but you cannot sell/buy them. But I'm unsure how the law goes about buying one abroad and having it shipped to you.

 

[Sigurthr]

There ya go, that works too. Keep in mind it is Chinese holiday right now (and for a few weeks, I think) so you can't place any orders yet.

The DTR modules are complete packages only requiring a host/heatsink to put it in and a power supply/battery, and while they are more expensive than Chinese lasers, they are of much higher quality. I've heard no problems from OL though, so to each their own. =)