Originally Posted by
pontiacg5
With 50PSI of clean shop air, a modified (extended) air blast nozzle and a 100mm focal lens I can blast through 1/2" MDF in a single pass with my 80W RECI tube. I run about 10mm/s for a speed at 90% power.
Air is your friend. Toss the cheap POS pump that came with your laser and get it set up on some real adjustable air pressure.
The adjustment knobs on the last mirror are for adjusting the squareness of the cut. You need to have the laser beam enter the carriage dead center from the nozzle or you will never get it right. This may take some adjustment of the carriage or position of the 2nd mirror on the long X axis rail, mine came straight from gweike way too far out of alignment to ever get a square cut.
After that you need a thick piece of clear acrylic. Test fire the laser into the acrylic and fiddle with the last adjustment mirror till it appears to be exiting at a perfect 90 degrees. If the laser does not enter the carriage properly you will hit the side of the air blast nozzle before you find the "sweet spot." You'll know this is happening when you see semicircles appear on top of the acrylic.
It takes forever and a day to get a laser to cut right and true. After it's set do your best to not bump or move it at all. Set the rubber feet, don't rely on the wheels. Be extremely careful when you clean the mirrors. Don't touch them, drag an alcohol soaked cloth across them. They are clean when the alcohol evaporates and you can no longer see any crap stuck to the mirror.
Hope that helps!