Hello together, I need to build a laser engraver with 6 lasers (to engrave

Hello together,

I need to build a laser engraver with 6 lasers (to engrave 6 identical pieces at the same time).

Can anyone help me out with how to connect the lasers?

I’m pretty familiar with 3d printing and I have all the movements covered. The only thing missing is how to control the lasers (they all engrave the same image).

Thanks alot,
Richard

@Richard_Rohan ​ very interesting project.

I assume this would have to be using solid state diode laser modules. Most are just turned on/off with a 5v TTL signal. A single I/O pin from a micro controller probably cant drive that many devices due to current limitation. You can use a line driver for that purpose. 74ls244 is a octal line driver. Just tie all all input pins to the same micro controller output pin. You now have 8 separate outputs. Use one for each laser diode.

If this is a laser diode with analog input, that would be more difficult. I have to think of a cheap way to do that. A non inverting unity gain op-amp maybe.

Hi Jim,

This sounds not promising.

Yes I’ll be using 2500 mW modules which have only 2 wires - I think those are pwm or?

I was planning on using just the fan output (pwm) to drive the laser.
Could I use just a mosfet board (like the ones on 3d printers)?

But thanks for your answer, I hope I can find a solution where I don’t need such things you mentioned.

Regards, Richard

@Richard_Rohan you can still use the octal line driver for PWM output. It’s a single IC chip that is really easy to hookup. Sparkfun makes a good inexpensive board you can buy.

which controller board are you using?which laser?

I was thinking about using an arduino with a ramps board on marlin.

@Richard_Rohan not sure how well marlin supports laser but grbl does it really well.

Im not sure where I read it but I think there’s a GrBL for ramp out there

I chose marlin because I need a standalone machine performing the same task over and over (at least the machine needs to ein 1000 times as we need 6000 pieces engraved). So wanted an LCD and local inputs to start each cycle.
Marlin lead me to arduino with ramps.
The gcode can be edited to fit perfectly since the time for that is nothing compared to the 1000 runs.
Marlin supports g2 and g3 and I can reprogramm it to use the heatbed and fan connector to be switched by a M3 and M5 command (or I just simply search and replace those with the commands for the heatbed / fan in the gcode).

So I pwm control one laser from the fan out (as an example).

It’s just that I’m unsure what will happen when I connect all 6 of them with a mosfet (they draw alot of current). I don’t wanna blow those since they are quite expensive.
I could use a mosfet for each and connect just the control wire (which triggers the mosfet) to all of those.

I could do grbl on ramps too and send the gcode from an raspberry pi.

Is producing this with say " ponoko " not an option?

@Ariel_Yahni_UniKpty to be honest. Giving work out is not an option.

@Richard_Rohan it’s ok, just asking. Sometimes labor & timeframe can be solved by outsourcing

Before I can add more input, kinda need to know which laser module to see what they recommend on hooking it up.

@Ariel_Yahni_UniKpty it was our first thought and we got some offers for that - but those were too expensive or they wanted is to use their wood so we decided to make it ourselves.
We figured out that the cycle time is around 2.5 hours and we can make 6 pieces in that time so we decided on a 6 laser machine (instead of 6 single ones - which would be much more expensive).

Your idea is in most cases the way to go and many thanks for that suggestion. I didn’t know ponoko.

We went back and forth many times and we need to have it made in-house since the engraving is our signature of the product.

@Richard_Rohan understood. So http://let.me ask you something else. How big is the signature? If I understand correctly 2.5 hours for 6 engravings seems a lot of time. Is it a large engrave? Or you need to go slow because of the diode not marking hard enough?

The engraving is about 300x100mm and is covering the whole area (our cheap engraver needs 2.5 hours for it). We need to drive slowly also to capture the details.

How much is that diode laser. Here is what I’m thinking, co2 laser can engrave at much faster speed

@Jim_Fong ​ I have currently just one laser which has no extra pcb board and just 2 wires. So I could buy other lasers (maybe those with the extra pcb - I guess that will be a driver for the laser).
They cost around the same so it doesn’t really matter. Those lasers need a ttl input which I can generate on the arduino or convert the pwm to ttl (from my understanding those are really close).
So I’m quite flexible on which lasers to use - I’ll buy those which will get me the easiest setup.

@Ariel_Yahni_UniKpty around 60 € each. We thought about the co2 too… Those would be much faster - but I had tons of v-slot rails and wheels laying around so we used those to build the machine.

A pre build machine is out of budget and we already build the frame for the machine.

All I really need is a way to connect 6 diode lasers to one controller.