Hello, I'm currently working on a laser cutting extension for my Prusa i3 to cut thin material (paper or balsa sheets). For that purpose I ordered a 445nm M140 laser diode (2w) with a G2 lens. (link). I already created a constant current driver which delivers about ~1.65A with an electronic on/off control; my questions are about focusing the laser diode beam. 1) What is the distance to set up between the surface and the laser module ? 2) I suppose there is a manual adjustment to be done on lens by (un)screwing the "lens ring"; how to adjust that ring to optimize the beam precision knowing that I wear laser goggles preventing to see it? - 2.a) Do I need to create a smaller laser driver with very low output current to be able to safely calibrate the beam without going blind? - 2.b) What is the safe current level (10mA as for normal LEDs ?) 3) How to deal with the relationship between 1) and 2). Distance vs Focusing. Thanks in advance. https://reprap.org/forum/read.php?133,267853,267853#msg-267853 Fri, 04 Sep 2026 18:55:01 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?133,267853,275073#msg-275073 https://reprap.org/forum/read.php?133,267853,275073#msg-275073 diode is driven at 2 amp
There is a gold ring below diode that I twist to adjust lens
and focus laser.
Laser light only hurts close to focus point. (still have all my fingers -- unburned)
I use a set of red glasses (made for Blue laser) I can still see quite well

;)]]> cozmicray Laser Cutter Working Group Mon, 02 Dec 2013 15:21:44 -0500 https://reprap.org/forum/read.php?133,267853,269585#msg-269585 https://reprap.org/forum/read.php?133,267853,269585#msg-269585 I'm currently building a smaller driver without electronic on/off control for delivering a test current of about 250mA (seller said me the threshold is 200mA to get a laser beam).]]> vinch Laser Cutter Working Group Wed, 20 Nov 2013 05:03:41 -0500 https://reprap.org/forum/read.php?133,267853,269443#msg-269443 https://reprap.org/forum/read.php?133,267853,269443#msg-269443 www.ebay.com] and still putting together my heat sink and driver circuit.

I got cheap red laser safety goggles for doing low-power focusing. It was pretty easy to focus a low-power beam well enough to get about a 0.2mm burning beam. For testing I've just been using a current-limited bench power supply. My threshold current is around 80mA.

Thanks @vdx for the suggestion about black paint on a white tile for getting a more precise focus!]]> papergeek Laser Cutter Working Group Tue, 19 Nov 2013 17:08:48 -0500 https://reprap.org/forum/read.php?133,267853,268178#msg-268178 https://reprap.org/forum/read.php?133,267853,268178#msg-268178 vinch Laser Cutter Working Group Sun, 17 Nov 2013 03:28:06 -0500 https://reprap.org/forum/read.php?133,267853,268075#msg-268075 https://reprap.org/forum/read.php?133,267853,268075#msg-268075
For setting/measuring the focus distance/diameter I'm adjusting the lens with activated laser at lowest possible power (see 'threshold') and blow fume into the beam or beam into water with a small amount of milk mixed in.

The focal distance adustment is best made with black paint on a white tile and engraving lines with different distances ... the thinnest lines (around 0.03mm) are burned with the exact distance. Then make a measure with this distance to adjust the Z-height with objects of different heights ...]]> VDX Laser Cutter Working Group Sat, 16 Nov 2013 17:28:54 -0500 https://reprap.org/forum/read.php?133,267853,267853#msg-267853 https://reprap.org/forum/read.php?133,267853,267853#msg-267853
I'm currently working on a laser cutting extension for my Prusa i3 to cut thin material (paper or balsa sheets). For that purpose I ordered a 445nm M140 laser diode (2w) with a G2 lens. (link). I already created a constant current driver which delivers about ~1.65A with an electronic on/off control; my questions are about focusing the laser diode beam.

1) What is the distance to set up between the surface and the laser module ?
2) I suppose there is a manual adjustment to be done on lens by (un)screwing the "lens ring"; how to adjust that ring to optimize the beam precision knowing that I wear laser goggles preventing to see it?
- 2.a) Do I need to create a smaller laser driver with very low output current to be able to safely calibrate the beam without going blind?
- 2.b) What is the safe current level (10mA as for normal LEDs ?)
3) How to deal with the relationship between 1) and 2). Distance vs Focusing.

Thanks in advance.]]> vinch Laser Cutter Working Group Sat, 16 Nov 2013 03:30:09 -0500