Eleksmaker A3 Pro. Safety Concerns

Hardware GRBL
#1

Hi,

Does anyone know about any hacks/fixes that would ensure that the laser diode (in my case a 2.5W), doesn’t fire unexpectedly when power is turned on the controller?

I just finished building my unit (from Banggood), The machine works fine with the stock software. I’ve done some “fake” engraving with the laser off, because I’ve seen at least one video on YouTube that spoke of the laser diode burning a hole in their desk the second he turned power on!!

Also, are the glasses supplied with the Eleksmaker kit any safe? How do I find out, short of turning the laser on and possibly exposing my eyes to any stray reflections?

I intend to build an enclosure with a clear window (should I use acrylic?) to prevent stray reflections from coming out. I might also add limit switches.

Would LightBurn do a better job of preventing this unintended laser misfire? Or is that a hardware issue with the Mana SE board?

Thanks for any input, insight, links to useful websites, etc.

Steve

#2

The problem with the laser firing when powering up (will also happen on any reboot) is the boat loader in the Adruino lets the D11/Spindle/TTL pin float for a little bit when it is initializing the board.

There are two ways to fix this -

  1. if you have an AVR you can load the GRBL code into the controller without the bootloader (what I have done) and there is no more problem. Only restriction is you MUST use the AVR to load any future code into the controller because there is no more bootloader.

  2. You can put a 1K resistor on the TTL line to ground. This will keep the signal low during power up.

2 Likes
#3

Hi @wild.bill
Thank you so much for your suggestions. I will try the 2nd suggestion with the 1K resistor.
Do you recommend I use the safety glasses that came with the kit, or are they insufficient protection?

#4

I did use the glasses that came with the kit. My understanding is that any acrylic will block harmful part of the reflected laser light. When looking at the work being done I did make a point of finding an angle where I did not actually see the laser light just to be safe.

The reality is that on that machine I took the laser off and put on a drag knife to cut vinyl. I have a couple of CO2 lasers that I use for everything now.

#5

Sounds good. Thanks for your replies.

#6

Another way I use to resolve without a resistor is to sequence the boot order: 1 - power up the pc; 2 - load software (LightBurn); 3 - load project; 4 - connect to the laser com port; 5 - wait for connection; 6 - power on the laser. You will not have the unexpected (but predictable) laser flash.

#7

I would not trust that technique because anything could cause the USB connection to drop and reconnect, and that would cause the board to rese and fire the laser. I just don’t trust USB on the PC that much. The AVR only cost me $8 and is always safe.

#8

I used the 1K res trick on my A3 to cure this problem, worked well. For glasses and covers, the green ones that come with the A3 are ok, but cheap. I splashed out for a pair at around £35 from Amazon. https://www.amazon.co.uk/gp/product/B07BM5BTM6/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

For covers, you can’t use clear acrylic with a 445 Nm blue laser, it isn’t absorbed. So use an orange colour. Clear is fine for CO2

Cheers

David

#9

Thank you for the info, @DavidF
I appreciate it.
Steve

#10