I have a 15W diode laser with air assist. I get very inconsistent reults when cutting plywood. At one time I was able to cut through 1/4" baltic birch (available in Canada at Windsor Plywood) but lately getting through 3mm baltic birch is difficult. Just wanted to share my results and see if anyone has had the same experince or has some tips to offer. Here is one of the issues I have come accross.
I have focused the laser and done a number of trials (slope test) to figure out the optimal height of laser
above surface and number of passes to get through the plywood. I then proceed to to cut out small test pieces, usually increasing passes from optimal settings to ensure I cut through the plywood. Cutting small diamter circles and squares works no problem. When I move up to larger cut paths I get mixed results. Most of the time I do not get through the plywood and cannot remove the piece, even though the small cut tests fall out of the plywood with no effort. I know there are inconsistencies in the pywood. Now I am leaning to shorter cut paths done quickly seems to get through the plywood. My theory is on longer cut paths the glue in the plywood cools off and resists the laser on the next path. I can use the exact same piece of pywood and cut out small test pieces successfully exactly where larger cuts have failed. Maybe my TTL driver/laser heats up over time and the power drops? Anyone have the same experience or have a tip. Any suggestions on another plywood to try?
I have seen similar results. Able to cut easily one day then not the next on the same material. Only diff I could see was the temperature in my garage. I have also concluded that the material (and glue) are cooling between passes on the larger cuts. I have thought about using heat lamps or old printer heat beds to warm the material before or during a cut. But I have not tested my theory’s.
I have also worried about over heating my laser if I do this.
Yes but not quickly. If I remember correctly… The Diodes are good for something like 10,000 hours before they hit their half life. That can be cut short by excessive heat.
I thought of that as well. In my case no. The lens is still clean. So the best I can figure is the temperature of the material affects how deep I can cut. But again that is just a theory. I have not tried to test that yet.
I can’t speak for Bryan but yes I have. When I was testing I tried different thicknesses and types of wood. 1/4" ply wood (particle board and cabinet grade), 1/8" ply wood and a few others. But I was getting so confused by the variable results. So I switched to solid wood pieces to eliminate the glue variable. Even with solid wood there was variablility. I was using the same machine and same gcode files. I got to the point that I was able to reliably cut through wood that was 2 mm, 3 mm and even 6 mm thick. My test cuts were 50 mm x 50 mm test rectangle patterns. I was charting how many passes were required for each thickness.
Then a couple days later I tried again. it was colder in the garage. I couldn’t even get my exact same tests to cut through the 2 mm soft wood.
Thank you for the suggestions. I really do appreciate it. But at this point I can’t think of anything else that changed except for the temperature of the garage, machine and material.
I formulated a few ideas to test further but then life happened and I have not returned to that project yet. Now it is getting warmer weather so I expect these same cuts will work fine now.
EDIT: I should add that I am using a 5.6 Watt Endurance laser with the standard 3 element lens focused at an ideal 65 mm distance to the surface material. While I no longer recommend Endurance lasers to people this page has some GREAT info about common Diode laser lens types.