Burning questions about burning...

[GoolGaul]

Hey All,

Been lurking and occasionally commenting for a while. Lots of info flowing around here, and thanks for everyone who is openly sharing their know-how...

My real hobby is Halloween. Wifey and I throw a major bash every year (100+ people) and we also decorate like lunatics (some of our home-made decor has become year-round) inside the house, and we do a big cemetery scene in the front yard.

Every year I like to add a few new tombstones and other misc stuff, and mostly it's made of that blue/pink insulation foam.

Who can guess what my questions are?

Is there any wavelength that would be ideal to burn/cut either color of foam?
What kind of power might be required?
Would stepper motors suffice or do I need to use scanning galvos?
Why are eggs-over-easy so damn hard to turn over? (yeh,yeh.. it's not laser-related, but still a burning question).
Is there any off-the-shelf software/hardware that could control such an operation?


Thanks again for sharing all your experience...

 

[Flaminpyro]

I'm pretty sure stepper motors will work just fine for you and I'm looking for that software..someone just posted a thread but I can't remember the title of it but it is about just what you want to do with cutting your foam.

 

[Cyparagon]

A hot wire is better for cutting foam. A laser is slower, more dangerous, more expensive, more complicated, and (unless you spend several grand) much less precise.

 

[Krogith]

Are you using it to draw things into the foam? Or are you just cutting the shape? Honestly I think a hot wire will cut your shapes out 10X's faster. But if your using it to basically "Draw" on them i guess you would use a 405nm or 445nm... But I personally think it's going be harder than your thinking it will be with a laser...


EDIT: BAH Cyp got it in seconds sooner...

 

[GoolGaul]

I use a hotwire for cutting and shaping, as well as soldering irons, X-actos, and more. I don't expect a cheap laser to cut thru 2"-4" of foam... but it would be nice ;-)

I'm asking about lasers for 3 reasons:
1) ease - some of the shapes/lettering/etc can get fairly complicated and thus hard to cut, especially with a high level of consistency. When cutting, the razors and hot-blades can get "pulled" in the wrong direction, and when you're carving the last letter on a complex tombstone, and screw it up, well... I a sure you can imagine THAT feeling.
2) repeatability - I have loads of people that ask me to make TS's for them and I have to decline, as I am fairly time constrained... If I could make a template/pattern/cadfile and then "run the program" and come back to it in a half hour (for example) the system would surely pay for itself in 2 seasons.
3) Complexity - I know that I can control a laser with more precision than my hand, and can do much finer work. I can only work at depths that are pre-determined by my tools, where a laser can achieve differing depths, just by lingering a little longer.

Plus, I am kinda lazy.

Here's a sample of my work...

granted this was easy to cut (the scroll-ish thing on the front with the word "beloved" on it, but if I had more control, I'd have gone a bit further with it.
BTW - the whole thing isn't carved from foam, the dress and wig are real dress and wig, with Monster Mud, the head is one of those wig-stand-heads, and the hands are clay and pipe cleaners. and yes, we do make the candles too - PVC pipe, GlueGun, some off-white paint, and those LED TeaLights...

thanks in advance for all the advice...

 

[InfinitusEquitas]

Always annoys me how little practical utility there is to handheld lasers

A lot of fun though.

EDIT: That's nice work.

 

[Eudaimonium]

See here if it is OK with your desires. Imagining that cutting out precise shapes via CNC plotter is not difficult - it's fast enough and will do the job.
EDIT- addendum - It's not my laser, it belongs to billg519, also a member of this forum.

 

[Krogith]

I really Honestly think that a Laser will not work like what you want. As you can see in eud example it's going to be really hard to get it to work. And Honestly 2 Watts of IR is VERY Dangerous.

Now if you Built a CNC unit and did Digital Drawing in a program and then had it cut it for you... thats a Whole beast in it self...

If you decide to go with a 2W IR laser read up on Safety Please. Most of us don't even own Ir because of how dangerous and we don't really have a use for it in any normal application....


EDIT: and just so you know, it gives off no light im not sure if you caught that the camera used in the video above can see IR. And you will see no light what so ever except maybe a glow at the point of impact. thats why IR is so dangerous, you can;t see where it's going, Bouncing Etc...

EDIT2: Honestly I don't even know why he suggested you get a 2W IR laser. If you do that get all the Right safety Precautions. And go CNC Please. A hand-held IR laser will be to dangerous of a tool and wont even give the desired effect. You seem to be doing a Awesome job as it is.

 

[AJ_Dual]

Hmm... That 2W of IR would do nicely if you had it set up to do "cookie cutter" style stacks of 2" foam which are then stacked up, and can be given a final shaping/rasping to produce a smooth contour before coating with the mud/grout/paint or whatnot.

Is this your plan for such a plotter?

 

[Eudaimonium]

I didn't suggest anything, Krogith. I merely showed him what type of power is needed to get semi-acceptable results.

If he is going to get a laser powerful enough to cut foam, you'd figure out he also knows it *might* be dangerous.

 

[Krogith]

Showing a hand-held 2W IR and expecting him to make a CNC unit is like showing a kid candy and expecting him to want spinach. IMO

 

[Eudaimonium]

And what kind of power do you think it's suitable for CNC cutting of materials? Class II?

He will get higher power lasers no matter what. Might as well start the topic now and inform him of all laser safety issues associated right away instead of *blindly* waiting for a disaster.

OP, do you know what having such a high power laser implies in therms of safety regards?

 

[GoolGaul]

that's one thing I really like about this website, the bold emphasis on safety.

I didn;t feel that I was being directed to buy such an animal, and to be honest, I wouldn't even think of messing with that kind of power, especially when it's invisible.

but now I know that it is out of my expertise, and will likely stay that way for a while.

 

[danefex]

That's awesome. My wife is a Halloween nut too, 20X more and worse than me. After reading your original post we seem to be in identical situations when it comes to the 31st. It's the same over here, every year for the past 7 now we've done halloween and added something different (pnmeumatics lately) each year. We have the entire neighborhood on our property for a good 4 hours on halloween for the past 4 years now. (not everyday no, just the end of october)

I don't mean to hijack anything from above that's already been addressed regarding your questions because I haven't read all the replies (short attention span + drinking alot) - but to answer your question. from what I do know.....

Eggs over easy is just a play on words, IMO they're never easy not matter how over they are :beer:

 

[Flaminpyro]

See there Krogith there is hope for mankind after all...

 

[Eudaimonium]

that's one thing I really like about this website, the bold emphasis on safety.

I didn;t feel that I was being directed to buy such an animal, and to be honest, I wouldn't even think of messing with that kind of power, especially when it's invisible.

but now I know that it is out of my expertise, and will likely stay that way for a while.

It's good that you are aware of the dangers regarding lasers too

Now, when talking visible/invisible, there's couple of things you should know, which heavily point towards infrared in CNC applications.

See, IR is generally regarded more dangerous because, it you happen to point it so that some of (or entire) the beam enters your eye, there will not be a blink reflex to save you from burning out your eyes.

Visible lasers can damage your eyes in two ways - First, optical effect which is literally overloading your photoreceptors so their fuses burn out. Ofcourse, you can't replace those fuses and your eyes are blind forever.

Second is thermal effect, when laser is powerful enough that, beside burning out the fuses, it also thermally damages the receptors and eye-lens, like it would burn/engrave any other surface.

Now, with Infrared, you do not have the overloading of photoreceptors effect because they aren't picking up anything. The only damage possible is thermal one, which happens if you have the beam enter your eye.

Now they are both very dangerous as handheld devices. With CNC equipement, things change a bit. There is no possibility of misguiding the beam, or part of it, into your eye.

So while having 2W visible laser radiation is quite dangerous, as staring into 2 W visible laser dot causes a lot of diffused light to enter your eye, overloading your receptors - where as with 2 W infrared, such danger does not exist because your eyes, as said, do not pick up any light. Only danger posed is thermal one, but that requires quite a lot of power entering your eye which could happen if you were engraving some shiny stuff, not decoration foam.

Now just to be clear - you don't buy an infrared laser, afix it to something stationary, and consider it safe. ALWAYS and more than always, be aware of the situation around you and where is the laser pointing, regardless if it's turned off. You may protect yourself, but you never know when will somebody open that door or walk through that hallway.

Always make sure it's safe to operate the laser, and everything will be cool. Accidents do not happen randomly. They happen when people get sloppy and do stupid sh*t.

So that's that. My advice is to get a higher power Infrared for cutting foam, because not only of reasons rescribed above, but also for larger selection area. You can have c-mount fixed IR lasers up to 5 W, and diode bars up to 100W of output power. So plenty to choose from.

In visible field, most powerful lasers you can get are 445nm blue ones, powers up to 1.5W (even lower considering 100% duty cycle is needed), or green lasers but those are incredibly expensive. Also, laser will not cut the material of the same color as itself.

With deep IR, color doesn't matter anymore.

If you happen to choose to push forward with this project, let us know how it goes