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2500 mw Laser Engraver - G2 Focal distance


Jun 24, 2010
I'll try that.....I had to use plumbers tape to tighten the lens thread so it doesn't jump around as you adjust. It is not the easiest thing to do with it set up on the machine. I try to focus at lower than 100% closer to 30% power because it burns thru what I am focusing and hard to see when it burns. I just remember it being hard to tell the smallest dot but the burn lines are easy to discern the thinnest line.

I have a few companies that build engraving machines that I supply modules for. The feedback I have is G-2 with a 30mm distance from the aperture to the work with good ventilation to get the tightest spot with best power density when using the high power multimode diodes.

If you do use Teflon/plumbers tape you want to put it on the bottom 2/3 of the threading toward the focus ring so it is just starting to thread in when you get to near focus. if it gets worked into the threading or eve you have it all the way to the bottom you risk getting little bits in the diode pocket and it can if the diode in the unit has a can burn up the diode window or if it is a open can like a NUB style diode that is what I have seen in all the engravings modules coming out of china can contaminate the dye area with the emitter or the bond wires and just blow the diode.

I highly suggest starting here as this step has saved so much time from being wasted with quite a few that I have helped with issues getting the unit to focus. If you unit can be pointed at a wall around 10 feet away then take two pictures real quick. Take one of the raw output with no lens in at all and then just screw the lens in so it is not falling out and makes a giant flashlight like output. This way we can see any possible issues. If you have been burning stuff the lens may already have a film coating on the lens which if left unchecked will eventually be able to block enough light that it just in a split second burns burns the material and you might get some smoke and melting glass on the lens. Any film can cause a lot of power to scatter making the unit near impossible to focus and look to not be very powerful.

Seet the picture below if you can get something like that of the output profile with and without the lens.

Was out last week and been catching up yesterday and today so sorry it took a bit to get back to you. I do try to get to the messages that I can answer fairly quick that are not going into a long dissertation to reply especially if they have a lot of info that can be found quick. See you got some of the info on your own and a lot more here in this thread. Anyway lets see what you have going on with the optics as the first step and make sure there is no issues there.:beer:

Mar 25, 2018
Been a long time since I put this up. I have made an adjustable z axis bracket for my laser engraver. The first pic shows G2 lens where I was making focus lines. I was at 32 mm from the balsa and I couldn't get a thinner line. The line to right is barely visible but it was at 65mm with a 3 element lens and it went completely thru the balsa. Next pic shows where I cut parts with the 3 element on some softer balsa and it went completely thru at 550mm/min with hardly any kerf. I just don't seem to get very good results with the G2. I just got a G8 in to see how well it will work but for now the 3 element seems to be the winner


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