Alan, I read you said “I cut a lot of card stock for scrap booking”. I have a couple of questions if you don’t mind:
1. How do you prevent paper from burning when cutting it with the laser?
2. How do you prevent smoke from depositing on the top? Or do you cut multiple pieces of paper at once by stacking them? This puzzles me and I can’t find any information on cutting paper on a laser.
Also, I read Rodney’s post on using Nitrogen Assist. I take it this replaces air assist, if I am correct? But how do you feed the nitrogen into the laser? I have no idea how this is done and haven’t heard of it until today. I suppose you feed it through the same tube that normally connects to the compressor. But I am unclear about the exact process. I thought Nitrogen was dangerous? Thank you for your help.
Nitrogen is very safe. The air that we breathe is 80% nitrogen. Oxygen and Carbon Dioxide make up most of the rest of air but I don’t recall the mix. Somebody enlighten us, please.
Burning occurs in the presence of oxygen. Nitrogen assist blows off the the particles, just as air assist does. But it also leaves the target oxygen starved so burning does not take place as readily as it would in air.
On a related but somewhat irrelevant topic, I have been told that optics are sometimes enclosed in nitrogen gas. UV at 193nm interacts with oxygen and creates ozone. More importantly, oxygen absorbs UV 193nm so that there is significant energy loss if the beam travels a meter or two from laser to target. Loss is something like 50% over a couple of meters travel. If the optics are enclosed and fed nitrogen so that the beam path is oxygen starved, then more laser energy gets to the target.
1. How do I keep paper from burning? - I find the maximum speed and the lowest power to do the job. But here is the kicker. It all depends on the graphic you are cutting. If you are cutting a lot of curves with nodes then you can get by with say 100% speed and around 15% power. If you have a lot of strait lines you have to slow the speed down because the laser zip between the nodes. It took me a while to figure it out. Draw a box and convert it to curves and then look at how many nodes it has (4). Now type in the small letter (a) and convert it to curves and then look at the number of nodes there are (many). The laser slows down cutting this even if it is at 100% speed so you must reduce power. This is where the line colors come in handy. Also this is how I have been discovering the ramp function. If I understand it correctly with power ramping it is supposed to reduce the power in corners so that it does not cause over heating. Since I cannot seem to use the ram function I am unsure if it will do what it is supposed to do.
2. Smoke. - I use an air assist and a lot of exhaust. You will get a little odor with it but it dissipates after a couple of hours. I do not stack cut just because I have not had much luck with it. With the air assist it blows the smoke on to the underlying piece. I have not tried the Nitrogen. I was wondering if it would decrease the amount of smoke or reduce any burnt odor. Also I was wondering if anyone used it how long a bottle might last. Nitrogen is an inert gas so things do not tend to burn well in its presence.