Ok, i have had my ortur lm 2 non pro 20 watt laser with the lu1-4 5.5 watt optical output machine for about 1.5 years. So far i have done alot of nwt, nwtpb, awesome wood engravings, and basic stuff.
However, one thing i have never done is used it for cutting. I want to start with plywood.
here are my questions:
What types of plywood are best? Baltic Birch? basswood? Pine? oak?
My goal is to cut 6mm plywood, but i would be ok with 4 or 5mm. i need to start somewhere.
What settings do i need to run lightburn at for 4mm plywood? I do not want to use 100% power since i am trying to save the life of the machine.
I have the Neje A40640 dual diode on my CNC, seems to be similar in power to your unit. I have air assist (25-40PSI), which I believe is a must for cutting, it blows away the char debris allowing for a deeper laser penetration per pass. I’ve cut luan plywood (5mm) from Lowes, baltic birch (3mm) from woodpeckers on amazon, walnut/pine/maple ply (5mm) source unknown, and oak/mdf/oak ply (5mm) source unknown.
luan ply 5mm cuts clean at 220mm/m, 85% pwr, 2 pass, fine focus, 0 Z offset, 1.5mm Z offset step-in/pass, tabs 2/shape @ 0.1mm size, air 40PSI, kerf offset 0.1mm
baltic birch cuts clean at 220mm/m, 85% pwr, 1 pass, fine focus, 1.5mm Z offset, tabs 0.1mm, air 30PSI, kerf offset 0.1mm
w/p/m 5mm 300mm/m, 85%, then same as luan
oak/mdf core 5mm 220mm/m, 85%, 3 passes, fine focus, 0 Z offset, 1mm Z offset step/pass, then same as luan
*note that a recent post has a good price on baltic birch and perhaps other plys, Purchasing Material
*note that I’ve had some luan ply which has a very tough glue between the plys, one which diode laser (445nm) does not penetrate no matter how many passes.
*boxes.py is a great webapp that generates dxf or lbrn2 files for many open and closed box objects with finger joints.
*elevate your material from any solid base workarea so that the hot gasses from the cutting process can exit the bottom of the material, makes for a cut with less power. Honeycomb, nail board, or I use an old steel bbq grill rack which allows for magnets to hold the material flat since these dimensions tend to have some warpage at times.
*ventilate/evac fumes, don’t breath this stuff.
Of course your settings may vary, but this is a starting point, fine tune from here.
ok, so i tested out some of those settings and mine is not as powerful as yours then. I did 300mm/min with 10 passes with 85% power and it cut through 6.12mm ply. I have no air assist either.
It might be how my focus works on my machine haha. Maybe if i added air, would cut faster?
I also had success with 600mm/min and 20 passes 85% power
add air, it will make a huge difference with penetration, and thus less passes needed. Search this forum for low cost solutions. I use my shop air system because its available dry air supply, but the volume of air through a 6mm tube at 40PSI has got to be fairly low based on how infrequently my compressor cycles on/off, perhaps 0.5 SCFM or less.
double check fine focus, it should be near 0.1mm for a diode laser. Also read about the effect of lens position for your specific laser, my laser’s lens position is adjustable by 1-2mm, screw in/out, changing the focal length by 10mm or so, and its position changes the conical shape of the beam, which effects the focal length and depth of field. Ideally for cutting, you want a narrow conical shape which also increases depth of field, if I recall all that correctly.
consider you may be running into the tough glue. For instance, I’ve laser etched some cutting boards where the laser did not damage/burn at all the glue lines between the wood planks, it just left a micro thin vertical wall in the etching. Glue matters.
and check your lens for clarity, since you’re not using air assist, you may have collected smoke and soot on the lens over past uses and that can diminish effective optical power delivered at the focal point. You may be able to clean it with Dawn soap and water solution, be careful with solvents as the lens could be plastic.
Relax with a pot of coffee and watch this video, it will blow your mind. Among other tid bits of info, the vid demos optical physics proof that one lens position can have more that one focal length.
Finally, when I mention above that I’ve run into some luan that my laser won’t penetrate no matter how many passes, you have ‘forced’ me to clarify ‘no matter how many’, which is about 6 passes in my case as I don’t have the patience for more passes
here’s a recent post with endorsement re a reasonable aquarium pump…Aquarium Air Pump
If you are doing NWTs, then you likely have your focus dialed in pretty good. Concentrate on cleaning your lens, adding air, and try some baltic birch 3mm. I made a few Christmas ornaments out of BB3mm and they were easy, fun, and great gifts. Same material is good for boxes too, also a lot of fun and sense of accomplishment.
Enjoy.
thank you, i will enjoy. Is amazon a decent place to buy baltic birch plywood? I will stick to 3 or 4 mm for small things, i only want to use 6mm for a frame im making that needs to be 12mm
but this place is 1/2 the price Baltic Birch Plywood | Ocooch Hardwoods
I just learned of it the other day as noted above, have not used it yet. I may buy some 5mm walnut veneer ply from them, I like how that cuts too. I made some puzzles using this dimension and similar ply, very nice stuff.
