Does anybody know if a 1-2W blue laser will cut .003” or so mylar sheet?
Also, how easy is it to focus the beam to maybe a .001” or less spot diameter?
Its hard to focus the beam that small and you will need proper fmsafety glasses in order to safelysz focus and use the laser.
445nm (blue) won’t give you tight focus, its multi-mode and not meant to create a tight spot. 405nm (bluray) 12x might have a chance.
No idea how well any wavelength cuts mylar.
LPF is a better place for detailed less common questions like this. Tho there are a few LPF members over here.
edit
Quick google search turned up a thread that might help a bit. Just skimmed a page.
Laser CNC, engraving works, cutting doable?
Diy 3 mil mylar stencil? :bigsmile: .001”is better then some professional mylar stencil services can cut with a CO2 laser.
Yep, my friend built his own 40 watt CO2 CNC cutter. Works well, but looking for something a bit better. I am thinking something along the lines of a 800-950 nm fiber coupled laser… something in the 2-10 watt range… might work better. I could even put one on my CNC mini-mill.
At NIR reflection off the material might be an issue. One of the benefits of CO2 is that many materials are non-reflective at 10,600 nm and material that is clear at lower wavelengths is opaque.
If NIR could produce better results at a reasonable cost I would think we’d see being used for stencils.
Some at LPF are quite knowledgeable about multi watt NIR (or any other wavelength for that matter) and have done cutting of various materials.
It doesn't take many watts to cut Mylar. It does, however, take lots of watts to cut Mylar CLEANLY. I've got several C02 Lasers at my disposal, and the smallest one that will make a clean cut without a melted edge through mylar or kapton is 150 Watts with a dual stage collimator. The beam width at the material on that laser is about 0.007", so it's a huge amount of power per unit area - something like 7 thousand watts per sq. inch. That can obliterate the material directly in the path of the beam so quickly that not much heat is transferred into the surrounding material - which is how melty/burny edges are created..
The 40 Watt solid state makes a mess of Mylar. It's really a 'marking' laser, not intended for cutting.
PPtk
Well, if I can get a couple of watts into a 1-3 mil spot, thats around 100 kW / sq in …
My friend’s CO2 laser can punch around 7 mil holes.
Been sanding off burn burrs with fine sandpaper…
It's late. I'm tired. I did the math wrong. The 150 Watt laser is WAYY more than 7 thousand watts per sq inch. It's also WAYY more than 100kW / sq inch. More in the 4 Mega Watts / Sq. Inch range..
150 / (.0035 * .0035 * 3.14159) = 3,897,675 Watts/Sq Inch.
Have to experiment. It may not take nearly that much if you can get the beam really well focused and figure out the perfect cut-speed and airflow..
Tsk, tsk… now you go writ on the blakbroad 500 timze “I will duble chek me maths befor I post…”
and you will say once i will not do math while tired
for making a small spot you could use a microscope objective. In a former life I used to work with optical tweezers: a 1064nm 5W laser (in those days it was 3 meters long with watercooling), coupled into a microscope using a 100x oil-objective (for 160mm image microscopes). In the focus there was around 200mW leftover with a spot diameter of around a micrometer, so that would be 2x10exp11 W/metersq. If you guys there across the pond would use proper metrics instead of ancient folklore units it would be easy to compare that to your numbers ;-)
I bought a 700 mW 405nm single-mode laser diode/lens/driver/heatsink and strapped it (OK, masking taped it) to a small desktop CNC mill. The laser was designed for use in 12X Blue-Ray writers. Single mode lasers can be focused to much smaller spots than multi-mode lasers. Total cost with safety goggles was less than $200. I also have a 3 watt/445 nm multi-mode laser on the way.
Running it at 500 mW for now. My goal was to be able to cut solder paste stencils for parts with pin spacings at or below 0.5 mm (.020”). To do that the laser beam spot needs to be in the 0.001” range (cutting kerf around 0.002”). Still playing with it, but it looks like it works! Laser is 4” above the work surface.
Image is of part of a circuit board that used parts in 0.5mm DFN20 packages. The pads are 0.2 mm wide with 0.3 mm spaces between them (.008”/.012”). Stencil was cut in red vellum paper (a plasticized cotton paper). Cutting speed was 5 inches per minute, laser running at around half power. Stencils need to be around 0.003” thick. Note that most people shrink the stencil openings some to compensate for the laser kerf width… as a worst-case test these pads were not shrunk any.
Sorry for the poor focus, it’s the best my camera can do.
Mylar cuts rather poorly, tends to melt and char. Might be OK with some assist air.
It can also cut Kapton (well, Kapton does not cut/burn, it chars) Resolution is not quite as good as the vellum but is quite usable. Again, assist air and some more fiddling should help.
Sticky backed vinyl and vinyl shower curtain liners cut very well.
Overhead transparency material is virtually laser proof.
Surprisingly kids construction paper and a bright orange printer paper from Staples probably cuts the finest features. Only problem is construction paper is .006” thick and the printer paper is 0.0045” thick. 0.0045” should be OK, particularly for boards that don’t have super-tiny pads.
I’ve got my solder paste stencil cutting laser working rather well.
Here I cut a bicycle out of .032” basswood (.063” balsa cuts the same) using the 405 nm (near-ultaviolet) single mode laser running at 1/2 watt. (I also have a 3 watt / 445 nm blue laser). The features in the bike drawing it was made from are 1mm wide. I measured the cutout bike and they are around 0.97mm wide so the laser kerf width is around 0.0005” !
ORSM. You are a mad scientist at large Pyro. But I guess I'm not the first to tell you that :-)
whoa. That's amazing to me. That strut going up towards the seat pedestal from the rear axle (please excuse my bike parts naming, if incorrect). Is that one of the cuts going through that strut along the inside of the rear wheel?
EDIT: I know the whole bike was cut out. I'm wondering if that fine mark is the "gap" from is one of those cuts.
EDIT2: Fixed some typo's above.
No, that’s just a mark from the pen I used to push the piece out of the sheet it was cut from. I’m cutting them now in two passes so the pieces pretty much fall out of the material. Otherwise some residual wood fibers, etc can hang the pieces and you need to push them out… and with 1 mm struts the wood can break… especially in balsa.
Are you going to offer custom stencils for solder paste? I am looking for a stencil for some triple XML MCPCB’s I had made.
Cut some scaled down bikes… smallest one has 250 micron features. I tried an 1/8 scale one (125 microns) but the bike winds up being made out of mostly ash and falls apart. Material was .032” basswood.
My beam width is around 12.5 microns.
I also tried marking tiny text on Kapton. 50 micron high characters are almost legible if you know what you are reading. 100 microns are easily read (if you have a microscope).
Amazing, you deserve the plaque on your door - Step quietly, genius at work!