Wont cut 3mm ply

Can someone point me in the right direction with regards to trying to cut through 3mm ply.I am using 6550 40w and I have tried every speed/power settings that i can and the laser will still only cut so far through.I am obviously missing something.

you need to do several passes for cutting thicker material. In the layers/cuts menu in Lightburn where you set your speed and power there’s a setting for “passes” put it to 3 passes for example and add more until it’s cut through. you need to test it out for your laser and the material it’s individual. I cut 3mm ply with my 5W laser in 4 passes, 80% power and a speed of 500mm

i have tried several passes to be honest.I am presently trying 750mm 90% power and 10 passes and still nothing near cutting through

hm that sounds weird. Have you set the focus of your laser? Also try to clean the lens with a q-tip and alcohol after every cut / engraving project, because the smoke will leave the lens messy and this can reduce power too.

i have the adjustable z axis wich is set spot on and i actually cleaned the laser this morning before i fitted the air assist

well with 40w, 10 passes, 90% power and a speed between 500 and 1000 it should definetely cut through. like I said my module has only 5W and cuts with fewer passes. I’m not a professional and I would suggest you to wait for more answers here but to me it sounds weird, like either the focus is wrong or something is broken. Have you cut something before with this laser? And could you send a screenshot of your settings in the layer tab?