What size laser for cutting foam?

[Laser Dude]

Hi,

So I've read up on the basics, safety, drivers, etc, but I'm still a bit unsure of which laser I need. Specifically, I have a CNC X-Y-Z machine and need to cut 1/4"-thick foam sheets (like the dark grey packing foam in camera cases etc). It seems a blue laser would work, but I'm still unclear on what power I need for this.

Ideally, I'd like to buy a self-contained laser that has the driver, diode, lens all built already, and I would make a mount to attach it to the CNC machine. I'm very good with electronics, so I can do that part if necessary (or if there's a significant cost advantage to that).

I'm currently looking at this page, but again not sure what size I need... https://sites.google.com/site/dtrlpf/home/diodes/9mm-445nm

Any recommendations?

Thanks.

 

[upaa27]

Hmmm. Styrofoam is white and by melting it it would make a nasty cut with a multi mode 445.

I say use a single mode 405 with maybe an assist for a cleaner cut.

 

[Laser Dude]

Oh... not the white styrofoam, but the dark grey stuff you'd find in camera cases, etc. I did also see that somewhere else about 405 giving a cleaner cut that 445, so I'm on board with that. But what about power -- I'm still not sure about that.

 

[The Lightning Stalker]

I first of all recommend getting a good
pair of laser safety glasses.

Picking a diode depends how fast you want
it to cut and/or how much money you are
willing to spend. An S06J would do it, but
probably not at any great speed. The new
BDR would be a little quicker. Really, if
it only has to cut 1/4", I don't see any
problems with the 445nm multimode diodes
either unless you plan on cutting thicker
foam at some point in which case you may
run into problems with depth of focus.

For a driver, you will have to go with
something like the flexmod that is designed
to reliably bring diodes above and below
threshold.

You should also not completely rule out
CO2. That would give high speed cutrates
and the ability to cut thicker tougher
materials of different colors.

 

[Laser Dude]

I first of all recommend getting a good
pair of laser safety glasses.

Absolutely! I'm usually paranoid about these things. And I don't include this in the budget as I won't skimp on it to squeeze in a larger laser, etc. Whatever that costs, it costs.

Picking a diode depends how fast you want
it to cut and/or how much money you are
willing to spend.

Off the top of my head (without having done any research yet), I thought it would be nice to clamp a ready-made laser pointer onto my CNC machine for $100 and cut away. If it's $200 for the right setup, I'll do that. This page somewhat indicated that 300mW would cut foam easily, but that's ~2mm.

FWIW, longer term goal is a 60W CO2, but due to size, cost, complexity, that's definitely longer term. For now I want to be able to make quick prototypes.

An S06J would do it, but
probably not at any great speed. The new
BDR would be a little quicker.

Okay, looking that up. I don't see the power for the 16X yet, but I found a 12X that is 500mW. Prices from $35-$65 which is fine. For some extra overhead, how about 1W (405nm)?... any of those available?

Speed is not important. I don't want it to take 2 hours to cut an inch, but it's just for prototypes, so it doesn't have to cut a foot a second either. Using my CNC mill as a rough guide, I'd say 10ipm would be fine. Precision is very important though.

Really, if
it only has to cut 1/4", I don't see any
problems with the 445nm multimode diodes
either unless you plan on cutting thicker
foam at some point in which case you may
run into problems with depth of focus.

Why go 445nm though if 405nm is cleaner? Availability? Cost?

I actually need to cut 1/8" - 5/32" thick foam, but I said 1/4" to allow for some overhead. And I never know what else I may need later so a bit of extra capability is always good.

For a driver, you will have to go with
something like the flexmod that is designed
to reliably bring diodes above and below
threshold.

That's fine. I am very electronics savvy and know I'll have parts on hand to build my own constant-current source, but for convenience I'll prob just buy the driver.

You should also not completely rule out
CO2. That would give high speed cutrates
and the ability to cut thicker tougher
materials of different colors.

Definitely later.

Thanks!

 

[Laser Dude]

BTW, this is the CNC machine that it will be going on...
https://www.youtube.com/watch?v=l65r4JPu3iM

 

[Laser Dude]

Okay, I'm seeing much fewer 405nm lasers, compared to 445nm. If I did go with 445nm (mostly for the ready-to-go convenience)... is this a good option?... 445nm 2W Ultra Powerful Blue laserpointer Burning laser with laser sword - $139.00 : Laser Pointer,Green laser,Blue laser, Red laser,Buy Laser Pointers,Cheap laser pointer

$149 with the goggles is not bad, but not sure if they're really 2W.

 

[BowtieGuy]

You may want to take a look at this thread before you buy from them.

http:// http://laserpointerforums.com/f51/2w-blue-laser-lucklaser-86692.html#post1259818

 

[The Lightning Stalker]

I recommend 445nm then just because they
will give a higher cutrate and are much
less finicky if there happens to be a
current spike. The difference in precision
isn't going to be noticeable, and may very
well actually increase due to the fact that
it will be moving quicker and not just
sitting in one place waiting for it to
cut. Meanwhile the heat affected zone is
increasing.

With all that space in the Z axis, depth of
focus won't be a problem either. Not even
with the 1/4" foam. Fume extraction WILL
be needed in any case!

 

[The Lightning Stalker]

There is a newly featured Instructable which
you may find helpful.

Shapeoko 2, Arduino UNO R3, grbl 9g, 8bit Laser Diode Photo Engraving

If that can etch photos, then it has more
than enough precision for your foam cutting.