Laser engraving, how to get started?

Hello !
I'd like to get into the laser engraving crew! But I am not sure where to start and since we are "playing" with laser I need to have everything squared before jumping on board.

I'd like to engrave PCB, wood and aluminium. PCB is my priority, so I think 445nm laser should be good, and a second laser for aluminium.
Attached you'll find a chart found in Reprap magazine issue 2; the laser section is a good read.

First safety, I'll need glasses. Are the ones found on eBay any good? how much should they cost?

Second, software. Seems straight forward to modify Marlin/Sprinter. Since we are not pulsing the laser it is either ON/OFF.

Third, the hardware. There is where I lack knowledge. Say I want a diode laser 1W 445nm. I'll need:

• 445nm Diode
• Optics
• Focusing optics
• Fiber optics?
• Power controller
• Fan
• Heat sink

I don't know on which website to get all my supplies. I don't even know if they'll all fit together.
I've found this:
[www.ebay.fr]
Would it be any good for PCB etching? Do you think it'll be plug and play?

What kind of budget should I expect? Is it the same thing with a 975nm diode? just swap it?

Any help is welcome.Hopefully this can become a guide for future users .

Cheers!
tleneel

Hi tleneel,

the linked 445nm-module should be already complete enough for engraving - you can go away with a singleneed a focussing lens or you can move the normal collimator optic in slightly greater distance to the diode, so it will start focussing the beam ... with too big distance you'l loose a big part of the beam, as the output is highly divergent.

One difference between the 445nm and a stronger IR laserdiode is the bigger needed current with the IR-diode (9 to 11 Amps with common 9W-IR-diodes, 1 to 1.6Amps with common 1W- to 2W-445nm-diodes) - beside the current driving/controlling is similar with constant-current-drivers.

The main difference with the different wavelengths is the material selection - IR 'works' only with dark or IR-absorbing materials, while 445nm is absorbed by most bright plastics or organics too.

But for engraving Aluminium the laserdiodes aren't sufficient - here you'll need Q-switched NdYAG- or fiberlasers with powers greater 30 Watts CW ...

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Viktor
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Call for the project "garbage-free seas" - [reprap.org]

I've been trying to get up to speed on using lasers - there is a lot of great information here.

I'm interested in using lasers for PCB etching (for example, using the method of burning away black paint before etching) and for cutting heavy paper (cover stock or card stock). And of course I want to do it as cheaply as possible, so I've been looking at the diode lasers from China and building my own pulsed power supply.

It sounds like for general use 445nm may be better for me. I've been thinking about getting the M140 2W 445nm diode with glass optics which DTR lasers is selling here in the US for around USD $100. WIth that an an inert gas source like argon or CO2 I should be able to cut heavy paper as well as etching PCBs.

Hi papergeek,

The M140 2W 445nm diode laser that DTR sells with the G-2 lens is good. You will not need a pulsed power supply as these diodes operate CW (constant wave) mode (i.e., either on or off). You will need a constant current laser driver for it. He sells one for another $40 US, but it is intended to be put into a "host" for a laser pointer. If you want to turn the laser on and off, it is better to buy a current source with a "TTL" input which can cylce the output of the driver to be able to turn it on and off. It is also good to buy an "adjustable" driver so you can turn down the laser if you are cutting paper and other things that don't require the full amount of power.

As far as cutting with the 445nm laser, it will cut a lot of things. Certainly paper and card stock. It will blast through it easy. I cut up to 1/8" thick balsa wood for hobbies. It can cut plastic as well. It is a bit color dependent (black absorbs best) and the thickness is about 1/16" maximum at about 100mm/m with three or four passes. I have not tried the etching thing, but we use it to cut solder stencils out of mylar for smd circuit boards.

I sell a kit with a driver for $224USD at: 1.7W 445nm laser driver kit. Or you can just buy the driver here if you want to buy the laser from DTR: 2.0 amp adjustable laser driver with TTL

You can check out the videos as well of it cutting stuff at the website in the blog. Remember to also include safety goggles in your estimate for price. Never use these lasers without them.

I'm also interested in getting some parts together to build a small engraver toolhead. Would the following parts be everything I need for the toolhead to work properly?

Diode with Aixiz lens and host
Aluminum heatsink
Driver circuit

I know I can get kits that have all the parts necessary, but I like sourcing individual components so I learn about how they work, and how they all go together.

Thanks!

... should be enough - but I'll be carefully with the "2W" or "up to 1.8A" - this is probably more than the diode will suffer for long time ... better stay below 1.4Amps, even with good cooling!

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

TopherMan-

This list looks good. It should also include a pair of safety goggles as well. These are very high power lasers and a single slip up can make you blind. You can find them on ebay from china as well, but make sure it has specs similar to the one in my shop: 445nm Laser Goggles

DTR sells very good lasers, so you are good there. However I agree with Viktor on this particular one. I would not expect to see this one go to 2W without the G-2 lens option. And you would be overdriving it a bit..

Not sure if the driver is constant current and it might be lacking some of the other safety features (soft start, transient voltage protection, etc...), but it is cheap. You might regret not spending a bit more on a driver if it blows up your laser.

The heat-sink is a bit hard to mount, but you should be fine with it.

Good luck and remember to get some goggles.

Jay

... instead of using goggles (that would change the visibility of the display content too) I've simply fixed an 'orange shielding plate' to the toolhead, that blocks all emission below 500nm in my direction ... see attached images ...

For the modified laser-equipped CNC-mills on my workplace and in the demo-centre I've ordered complete window sets to replace the clear windows in the housing with the orange shields, but at home I have more options as goggles and cameras (mostly for the IR-lasers, but for 445nm and other wavelengths too) and this 'partial' shielding is enough for occasional jobs with fast switching heads ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

@jtechphotonics couldnt a soft start be achieved with a small cap (say 1μF) before the diode in parallel? I think thats what most datasheets propose.

@VDX I had a similar idea for shielding as googles are not always convenient . What kind of shielding material did you use? PC ?

@waste: Yes, it is always good to have a cap in parallel with the diode to provide a clean source of current from whatever solution you are driving you diode from (i.e, LM317, FET, NPN...). If you put a relatively big one in parallel at the diode, then make sure it is discharged before you connect your laser.

In addition to these caps, the soft start that is on my driver board is a cap in series with a diode at the beginning of the circuit on the input power source. This will protect the entire circuit from transient high voltage spikes that can happen if you leave the power switch turned on and insert the power adapter as well as limit the in rush current on the regulator. A small cap with a diode (1N4148W for example) cathode to the positive rail will do the trick. The size of the cap will shape the input waveform and give it a small delay. In my case, you don't even notice it because it is under a second. It is also good to put a reverse protection diode on the input as well in case you accidently cross the positive and negative inputs from your DC power source.

a whole paper on the subject can be found here (but it is way overcomplicated):
http://www.ti.com/lit/an/slyt096/slyt096.pdf
and here: http://www.ti.com/lit/an/slva139/slva139.pdf

Sorry for the long winded response, I get energized when talking about electronics...

@VDX I am interested in what your shielding material is and where you got it as well. I want to put a sheet in front of my printer/laser with a couple of hinges to make a nice door.

... this special orange shielding was PVC, but I have samples from PMMA and PC too.

My samples were from Eslon - [www.eslon-plant.jp]

But there are other sources for shielding materials too ...

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Viktor
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Call for the project "garbage-free seas" - [reprap.org]

@jtechphotonics its a shame to ask for forgiveness when you share your interesting thoughts

If I have FETs around I prefer them for reverse polarity protection, as they have minimal power loss (only the RDSon which typically is way lower than the Vf of diodes)

but for the inrash current protection, you mean something like this??

ceramic cap diode cahode
+ ------ / \------------------------|------
|
1n418
|
- ---------------------------------|-----



@VDX thanks for the info

@waste- I think you got it. If you connect the top end to the input power and the bottom to ground. I have also seen it with the cap at the bottom like:

Vin -------------------------------------
|
cathode
---
/\
1N418
anode
|
___
___ Ceramic cap
|
Ground------------------------------

I'm seriously considering a diode laser for my CNC machine as well.
I have NO idea where to start, but an all in package for starters would be great.

Googling lead me to this link. I'm excited

JTech offers three laser combo kits, 1.7w, 2.2w, 2.8w kits.

I'd like some examples of what each power rating would offer to
help me make an informed choice as to which kit to purchase.

The 2.2 seems to be the happy medium as the 2.8 kit can
not be run at that power for extended periods.

So, what kind of jobs could each power rating do?
thanks!

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Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

... I'm driving my 2W-diode mostly with <1W average power ... so better buy the strongest and don't drive it too hard

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Would you mind posting some pics/examples of what you have done?
I'm leaning towards the 2.8w version...?
I already have Mach3 and would set it up to have the power controlled through gcode.

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--------------------------------------------------------
Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

... attached is a pic with some samples (the 'sharp' parts) I've done for an exhibition last year ... but most of the marking in this post can be done with the blue 2W-diodes and some 'tweaking' too ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Using a RAMPS board, which would be the best way to control this laser module?
[www.ebay.com.au]

I am building a complete laser cutter/engraver separate from my 3D printer, but using the 3D printer to make many of the parts.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

... look into the data-sheet, there should be a 5V input for activating the laser ... maybe even a 0-5V analogue input.

I'm driving my lasers mostly with PWM to adjust the average power in respect to moving speed ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Quote
VDX
... look into the data-sheet, there should be a 5V input for activating the laser ... maybe even a 0-5V analogue input.

I'm driving my lasers mostly with PWM to adjust the average power in respect to moving speed ...

Do you think a servo pin out could be used?

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

... any programmable output pin can be used ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Forgive me for butting in here but it seems like a good time and place to ask this question. I fully understand that engraving aluminum takes more power, but what about engraving colored anodized aluminum? In Viktor's video here - [vimeo.com] - it shows it being done. Was this done with more or less "off the shelf" laser diode or is the laser module tweaked and tricked up to get the capability. I am interested in a 1.5 - 2 watt 445 diode for doing this and PCB with the paint and etch method. Really interested in the colored anodized aluminum engraving. Is it doable with off the shelf hardware like a M140 diode driven to ~1.5W? If so, which lens, 3 element or G2?

Thanks, Mark

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I have a CO2 laser that I often use to engrave anodised aluminium. The power is turned down very low as not much power is needed. The engraving actually is done by bleaching the coloured dye that is used in the anodising process., exposing the raw aluminium that is underneath.
Aluminium is one of the hardest materials to cut, because it is a very good conductor of heat and there needs to be very much laser power to cut into it.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

... the sample in the video was done with a standard 2W-diode and a common lens too, I'm buying them "off the shelf" and use them without any change or tweaking.

Marking black anodized aluminium starts at around 1W and a focus diameter of roughly 0.05mm ... but there are some types of black (or more dark brown) coating, that will need more than 5Watts @445nm!

I'm using 975nm@9W-diodes too, that are equipped with a 0.1mm-fiber - here the best focus diameter is around 0.1mm -- and for removing the black coating I'll need up to 8Watts!

So it's depending on wavelength and focus diameter (or energy-density) too, what's possible and what not - e.g. colors or translucency not aplicable for specific wavelengths because of transmission or reflection rates ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks for the replies!

@Reg, yea, I'd love to have a CO2 setup, but I'm afraid it wouldn't get used enough to be worth the care and feeding of the tube. Maybe some day if I get my self into needing one on a daily basis, 80 watt, here I come!

@Viktor, thanks for the clarification. From what I have read so far, the G-2 lens would be better for this application than a 3 element due to the G-2 having less loss. Am I correct in this, or would a 3 element lens be better due to having a better, more round focus of the beam?

Again, thanks guys.

Mark

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From FreeCAD To The Real World- Demo video using FreeCAD and featuring the Smartrap 3D Printer

Quote
markstephen
Thanks for the replies!

@Reg, yea, I'd love to have a CO2 setup, but I'm afraid it wouldn't get used enough to be worth the care and feeding of the tube. Maybe some day if I get my self into needing one on a daily basis, 80 watt, here I come!

@Viktor, thanks for the clarification. From what I have read so far, the G-2 lens would be better for this application than a 3 element due to the G-2 having less loss. Am I correct in this, or would a 3 element lens be better due to having a better, more round focus of the beam?

Again, thanks guys.

Mark

When I bought mine about 10 years ago I thought that I would use it for just acrylic letter cutting (I was in sign work at the time) but after getting the machine I used it for so many things and still am, in fact I use it nearly everyday for something.
It is amazing the uses you find for these machines once you have one.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Quote
markstephen
@Viktor, thanks for the clarification. From what I have read so far, the G-2 lens would be better for this application than a 3 element due to the G-2 having less loss. Am I correct in this, or would a 3 element lens be better due to having a better, more round focus of the beam?

... lesser lenses count is better, as every phase change will reduce energy ... but good AR coating will help a lot too.

The focus is not round - it's more a bar with a bright center, what's good visible in the far-field ... but if the focus distance is short enough (max. some centimeters), then it's "small enough", so the averaged burning/engraving zone is a merely round area of maybe 0.05 to 0.1mm diameter ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks Viktor. I might just have enough info to move froward with this. I've caught your posts on venting the fumes and EVERYONE'S posts on the use of proper safety glasses so I'm good to go there. Haven't gotten any hardware yet, still in the planing stages.

Reg, yea, it could turn out that way for me, but I've gotten the oats on the wrong side of the horse a few too many times to jump right in. Maybe I'm getting old...

Mark

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