Sunday, May 22, 2016

Laser Unicorns

Eugene Has a Maker Space with a laser cutter.  It's a pretty cool machine that can cut acrylic and quarter-inch thick wood.  One of these days I'm going to have to cut cardboard stock and see if I can use it for various paper projects.

Alas, I missed the time two weeks ago someone used it to burn an image of their face into toast.
Last week I cut out an Eye of Horus.  That project mostly worked, except that for whatever reason, the cuts didn't go all the way through.  One theory is that the birch-ply I used has some uneven spots in it where the laser hits glue or a knot or something.  I spent a lot of last weekend with various sharp, thin tools prying at charred wood.

The Eye was good for giving me an idea of how close I could place cuts to each other without becoming too fragile (about a sixteenth of an inch) and what to expect using a laser to cut wood.
My niece has a birthday coming up, so I thought I'd make a birthday night light for her.

It took me a while thinking how to put box sides together, but I came up with a mortise and tenon design that would allow cuts from a single piece of wood.

Since the cuts were mostly straight lines, the design took about twelve minutes to cut.  I did a double-cut to insure there were no spots where the laser didn't make it all the way through.
When I opened the lid, there was the design.  I hadn't masked the wood with tape, so there were some burn marks (which I expected).

For the most part, it was a clean cut.  There were a few places where the bottom veneer was still uncut; I'm not sure if this is a focus problem or maybe places where the wood doesn't vaporize and so soot or ash is blocking the laser's beam.

The tips of the unicorns' horns were a bit charred.  I managed to hit the bottom limit to how small I can cut unicorns without damaging them (hey, what do you know:  it gets really hot between the acute angle a laser traces over wood).

I'd also assumed that the laser beam was one or two photon's wide, and that the sides' mortises and tenons would fit snugly into each other.  It turned out that (hey, surprise!) the vaporized cut is about thirty thousandths of an inch wide, which meant the quarter-inch cuts I'd made for the mortises were noticeably deeper than the quarter-inch thick tenons.  The difference wasn't too bad, and it gave the box a Frank Lloyd-Write or medieval appearance (especially since the mortise and tenons had a distinctly charred look to them).

I think for a more snug fit, I'd have to cut each side separately (so that the mortise from one side no longer form the tenon of its adjacent neighbor) and then scale them down about 99 percent.



"It looks like a puzzle," Mark said when I brought the box home to assemble.

I daubed wood glue between the sides.
My original plan was to have unicorn-shaped holes that an LED could shine through at night.

I went back and forth between wanting to leave the unicorns in their unicorn-shaped holes, or taking them out and gluing them on the plain sides.

Night-light functionality won out, and I left the holes open.
In this picture you can see where some of the veneer hasn't burnt all the way through.  I had to use an exacto knife to clean up spots like this.

I also wanted a picture of the side design, because rotating the sides in my head to figure out if they would mesh with the bottom piece and other sides was really hard.
I had cut out two square-shaped pieces of wood.  These became the box's lid; the smaller square fits in the rim, while the larger piece sits on top.
I held the box together with rubber bands while the glue dried.
At one point I was straightening up and I put one of the unicorn cut-outs on top of the box's lid.

"Oh!" I said, and so did Mark.  He convinced me that one of the unicorns should go onto the lid instead of the side.
"Serendipity" would make a good unicorn name.
Later, I put a LED candle into the box and nearly died from the squee! factor.

We're still debating a finishing.  When I asked The Child what he thought about it, he said that the burn marks made the lamp "look like it had been in a fire storm."

Also, it does smell a little bit like a campfire, which isn't the sort of thing parents like to smell in their children's bedrooms.

It's possible that glow-in-the-dark paint is in a unicorn's future...
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