Unlimited length cutting (Warning: Don't try this at home)

[John Blazy]

I would not normally do this. I thought of it a while back, but didnt need this ability - that is - removing the cover to expose the laser to shoot out into my shop, and mount the mirror and lens off a centilevered beam to manually push material through it like a bandsaw.

Until now.

I laminate dichroic films on glass and acrylic for commercial architectural spec, so with acrylic I usually crosscut the 4 x 8 sheets on a saw, or stack the sheets to cut all at once to fit them into my laser. The problem is that if any dust particles get on the sheet, and the sheets are flat stacked, or even vertical with the slightest pressure, the dust imprints dents into the laminated surface. So last job, I simply used a manual scoring cutter to score and snap the panels for shipping (customer has their own laser, so they wanted 48 x 48 panels) which minimized the dust tremendously. Way too sore on the arm to score and snap 1/4" acrylic though.

SO now on the job I'm on this week, different customer needs 40 x 40 panels from 15 sheets. Not looking forward to manually scoring the panels.

Gotta cut them without dust.

So I made a cantilevered beam that extends off a post in the shop where the mirror/lens combo fits off the end 14 feet from the laser. Mounted the mirror post through a hole in the beam, and mounted the lens under it at the right position, shielded in a length of conduit for safety shielding (Just repeat to myself - "this is theoretically safe now").

Worked the first time. Doesn't need to be pretty, doesnt cut all the way through when I push to fast, but it snaps right at my line - no dust.

Clsp-Mrr-Lens.jpgUnlimitedCutting.jpg

[Bert Kemp]

Aren't you the clever one .

[Kev Williams]

...do what you need to do to get the job done. I love it! Something I might do...

[Gary Hair]

You'll either be a good example or a cautionary tale - so far "good example" is ahead.

I would not normally do this. I thought of it a while back, but didnt need this ability - that is - removing the cover to expose the laser to shoot out into my shop, and mount the mirror and lens off a centilevered beam to manually push material through it like a bandsaw.

Until now.

I laminate dichroic films on glass and acrylic for commercial architectural spec, so with acrylic I usually crosscut the 4 x 8 sheets on a saw, or stack the sheets to cut all at once to fit them into my laser. The problem is that if any dust particles get on the sheet, and the sheets are flat stacked, or even vertical with the slightest pressure, the dust imprints dents into the laminated surface. So last job, I simply used a manual scoring cutter to score and snap the panels for shipping (customer has their own laser, so they wanted 48 x 48 panels) which minimized the dust tremendously. Way too sore on the arm to score and snap 1/4" acrylic though.

SO now on the job I'm on this week, different customer needs 40 x 40 panels from 15 sheets. Not looking forward to manually scoring the panels.

Gotta cut them without dust.

So I made a cantilevered beam that extends off a post in the shop where the mirror/lens combo fits off the end 14 feet from the laser. Mounted the mirror post through a hole in the beam, and mounted the lens under it at the right position, shielded in a length of conduit for safety shielding (Just repeat to myself - "this is theoretically safe now").

Worked the first time. Doesn't need to be pretty, doesnt cut all the way through when I push to fast, but it snaps right at my line - no dust.

Clsp-Mrr-Lens.jpgUnlimitedCutting.jpg

[John Blazy]

You'll either be a good example or a cautionary tale - so far "good example" is ahead.

I don't really want to be either, although I am kindof both right now, depending on what perspective you take. Anyone that owns a laser knows this can be done, and at the very least has wondered if the laser will put a hole in the wall if the 1st mirror and access panel were removed. So if you know that much, you also know the potential dangers of open laser, so its not like I'm being a bad example to unknowing kids. It's just an informative technique I'm sharing so that if the need arises, you can rough cut certain materials in lengths not limited to your laser bed's max capacity.

I did expect that if I sprinkled sawdust through the beam, there would be a fun fireworks display, but the dust falls through the beam too fast, so no photos there.

However, I did learn that the beam spreads out much sooner than I imagined. The spot that hit a pallet 25 ft away was over 1-1/4" DIA. I also discovered that one needs to clean the lasers primary lens as well as all the mirrors during routine maintenence. It had several spots that cleaned off with lacquer thinner.
dirtyLaser.jpg

[Kev Williams]

Laser will never cease to fascinate me...

I did expect that if I sprinkled sawdust through the beam, there would be a fun fireworks display, but the dust falls through the beam too fast, so no photos there.
Spraying Cermark into the beam might get you a fireworks show (ask me how I know)

However, I did learn that the beam spreads out much sooner than I imagined. The spot that hit a pallet 25 ft away was over 1-1/4" DIA.
Interesting- this means that even though the beam expansion within a laser box will be minimal, there WILL be SOME beam expansion, yes? Meaning, if it seems the laser one is using isn't engraving as well at the farthest point from the laser tube as it does at the closest point, then one is not imagining it..

[John Blazy]

as well at the farthest point from the laser tube as it does at the closest point

Thats what I was thinking - loss of power, farther away, however, the 20mm diameter of the lens "catches" the wider beam, and still focuses all the power. The beam DIA at the 14 feet away from my laser for my "off table" cutting was only about 3/8" DIA max.

[John Bronleewe]

Great post. At my previous laser gig we accidentally melted a 3/8" diameter spot into a computer keyboard while attempting to adjust mirrors on our newly arrived Chinese laser. The keyboard was about 12' from the machine and right next to where a co-worker was standing. Until that point I hadn't even thought about the beam going such a distance with any real power. As amused as we were it was it was a fast reminder of how easy it would be to seriously injure someone one or burn down the world.

I love your use of this mod!

[Kev Williams]

And don't forget, the larger the incident beam diameter, the smaller the focused beam spot diameter- I'm curious how tiny the beam spot would be if you capture and focus all of that 1.25" diameter beam?

[David Somers]

And of course, the real question is, can we do this with a Glowforge??? <sorry......evil question>

Cool idea John. I have no need to do this with, but it would be fun to try just for the giggle. And pilots were worried about people with laser pointers?? Wait till a creative teen with a Glowforge reads this thread!!!!

[Dave Sheldrake]

Wait till a creative teen with a Glowforge reads this thread!!!!

I've seen a home built shoulder fired 40 watt glass tube built into a rifle

Freehand lasers (a box with the laser head mounted on the end) are quite common in the pyrography game apparently, personally I value my eyesight a bit too much to try them out though

[John Blazy]

Wow - I can totally see a psychotic teen with great electrical skills take apart a glowforge for nefarious reasons. Its not the geeky teen that engineers a hand held version from a GF - its his evil buddy that "borrows" it.

Did a crap load of cutting today - ten sheets - three cuts each, no dust. Shipping Thursday.

Its amazing - no sound at all except a faint hiss. The real danger is breathing the fumes, so I wore a respirator and had our "air assist" shop fan blow the fumes out the bay door.

Off-cutting.jpg

[Bill George]

Add a few more mirrors and I see the basics of a perimeter security system that really protects you! NO do not do this!!

[Bert Kemp]

Great Idea

Add a few more mirrors and I see the basics of a perimeter security system that really protects you! NO do not do this!!

[David Somers]

Bill,

Add a few more mirrors and I see the basics of a perimeter security system

Sooner or later the neighbors will get curious as to why the postman gets shorter and shorter every day.