So tried and epically failed to laser, but learned a lot


#1

So today, went to make my first laser cut project on Clifford, who is an 80w laser for one of my medical projects:

So everything was going great, except I learned a big, huge lesson about placing things on the bed.

When I asked the bed size from the shop manager he replied 48", but that turns out to be the whole bed, not the honeycomb which is 46". So why was that important, well so the edges (I asked if we should cut it down to 45, since my part was 41 x 31 and the $90 piece of 1/4" black opaque acrylic was 48x36. “Nah, it will be fine, I will adjust the focus…” he said

Well, in case you are wondering, acrylic is astonishingly flammable when it gets going. So what happened? Well the part was up on the side rails, which are maybe 3-4mm above the honeycomb, and although he put weights on each side, when the first part (about 20" square with finger tabs) fell, it was “mostly cut” so it ended up canted, sticking way up above the work piece as you can see in the picture. This snagged the head in place, which baked (especially since it was now defocused) the acrylic. Within about 15 seconds, about a square foot was on fire. Luckily there was the fire extinguisher can right there, which took a good long while to put it out (that is a large thermal mass. Some dripped down into the honeycomb sticking the piece to the bed (fun to get that unstuck). The whole sheet was pretty hot for about 20 minutes. I will note the air assist and vent aren’t awesome on this laser, even before that, but man what horrible fumes.


Show and Tell
Pre Release: Mini PC Shelf
Last one for night - unintentional torture test of variable focus
#2

Love the nickname of Clifford, but I don’t ever remember Clifford burning things :stuck_out_tongue_closed_eyes:


#3

We have already seen a demo of the Glowforge shutting down if the head runs into something.


#4

Good lesson. Sorry about the setback and the loss of material. Good thing the Glowforge will be able to take into account the distance to the material!


#5

Scary! Had an employee once catch a 20x30" sheet of acrylic on fire in a vacuum former to “prove” we couldn’t vac form it. Not an easy thing to extinguish!
BTW, you can vac form acrylic, Just need to dry it first.


#6

Well, heck, I proved you can easily form it to the shape of a honeycomb!


#7

How’s that?


#8

Oh, I will add the workflow was slightly painful. I made the base box using MakerCase (awesome) and then brought the holes in from OnShape since these holes need to interlock with my 3D printed parts. Getting precision alignment in Illustrator sucks between a DXF and SVG. No problem, got it all done eventually. Then these guys use Rhino as their laser front end, which only eats a DXF. Except the stupid DXF export in illustrator for reasons I cannot fathom changed the units, so the part was like 10’ across. Luckily Rhino has a very easy scaling mechanism for DXFs.


#9

But this was on the wall nearby, which I thought was gorgeous… It’s about 1 meter in height, and the laser cut detail is amazing. Done by a high school student as a project.


#10

@Dan, with the situation I faced, I assume the GF, like in the coffee cup demo, would stop? This got nasty quick!


#11

This story makes safety considerations real. The air scoop on the end for the air assist hangs down and if there are any flappy bits of masking or material that jumps up higher than .43, it will come into play. I’ve had small bits of chipboard blow out and intefere with a cut or some aftermarket masking material on my own plywood come loose and interfere.

I appreciate seeing the acrylic blob and it does caution me to think about how the pieces in the cut will fall or lie after being cut.


#12

Wow, omg


#13

Wow–great reminder that anything that can tip down can also tip up into the works. Thanks for sharing the Unfortunate Events.


#14

Rhino has very good alignment tools as well. If it could only open SVGs you could probably eliminate Illustrator from your workflow entirely. A potentially better option would be to eliminate SVGs from your workflow, especially assuming DXF compatibility will be implemented by the time the Glowforges ship.


#15

I can only imagine the smell… Was clifford injured?(the head or optics?)


#16

Nope. Just needs a cleaning…[quote=“Hirudin, post:14, topic:5951”]
Rhino has very good alignment tools as well. If it could only open SVGs you could probably eliminate Illustrator from your workflow entirely. A potentially better option would be to eliminate SVGs from your workflow, especially assuming DXF compatibility will be implemented by the time the Glowforges ship.
[/quote]

MakerCase doesn’t export DXFs, so I had that to start, and I never use Rhino (this is another lab I do some work with)


#17

I’m glad it all ended up okay with no damage except to your material. What type of fire extinguisher did you use?


#18

Whatever this was… (The shop manager had pointed it out before we started “just in case”)


Glowforge shipping date, beta releases, and bonus materials
Accessorizing Your Glowforge (Like the Fashion Industry)
#19

If acrylic has been around for a while in a humid place it will take on moisture, this can result in bubbles when you thermo form it. Putting the sheets in an oven at 180F for 12 hours will drive the water out.


#20

Looks like this.

… great. The preview is “Robot Check”…

First Alert “Tundra” fire extinguisher.

A review (that I didn’t even begin to read)…
(for all I know it’s an ad - read with a grain of salt)
http://dailyhomerenotips.com/2010/10/20/product-review-tundra-fire-extinguisher-spray-can-from-first-alert/