bdring wrote:Technically you should never touch ZnSe with your bare hands. It is allegedly poisonous.
bdring wrote:FYI: Longer focal length equals larger spot size.
dirktheeng wrote:All,
I set up the laser to cut some of the plywood again yesterday, and I am getting dissapointing results! I am getting a lot of charing and I'm having trouble cutting all the way through (it just barely makes it through in a few spots with the 1/4" stuff). I have a feeling that it is due to the scratched lens. I haven't gotten a replacement yet.
I also think that the plywood from lowes is a problem. It has a core in that looks like balsa or fiber board. After doing some reading online, I think that this may be a big part of the problem. Plywood, apparently, is not a very easy thing to get right and the wood (especially the glue) have a huge role in how well it cuts. My understanding is that it should cut without producing enough charring that it leaves black marks on your hands when you pick it up. It may look black, but it doesn't leave your hands black when you touch it. It is also apparently very hard to produce edges that look just browned and not black, especially with stuff thicker than 1/8".
The charing with the stuff from lowes was bad enought that it noticably seems to change the dimensions of the part, especially at corners.
I also tried acrylic. It seems to cut much better than plywood. However, the edge isn't as nice as I had hoped for. It is a bit wavey. It's almost like the laser power isn't consistant as it cuts and the kerf width is changing or maybe there is a vibration in the optical system somehow (I tried turning off the air assist with no change in results). I guess I thought it would look like glass after being cut. Also, the power/speed of the cut seems to play a big roll in how square the edge is.
Also, I need help finding the right focal depth.
Can people give me some thoughts and/or advice?
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