Jewelry on Craig Andera

Pi Day Ring

Fri, 06 Mar 2026 00:00:00 +0000

My daughter generally designs jewelry for Pi Day. In 2026 she got done a little early, on March 6, which is eight days ahead of the 14th. Usually we're finishing up on the 13th.

This year's piece is a ring: ribbed, darkened bands with a pi symbol cut out across the front. The ribs are actually a mistake. Something to do with me setting up the rotary chuck on the laser wrong. But I liked the way it came out.

An earlier year's effort is on the Pi Day Earrings page.

Engraved Steel Ring Test

Fri, 20 Dec 2024 00:00:00 +0000

A polished steel channel ring with "This is a test" laser-engraved on the inside, from December 2024.

OneOne Earrings

Thu, 27 Oct 2022 00:00:00 +0000

These were a present for my daughter, since I very much enjoyed watching "Infinity Train" with her. They are in the shape of OneOne, a character from this delightfully surreal show.

The body is brass, investment cast. I think. The fill is epoxy, tinted with mica powder.

How they got made

My daughter was about to turn 18, and she really likes Infinity Train, which is a bit obscure: a surreal animated series. I'd wanted to do more jewelry, and I'd done a few rings, so I designed these earrings based on One-One.

Wax patterns (October 2022)

First step was 3D-printed wax versions of the earrings. These are the patterns. The plan was to cast them in brass and then enamel them in black and white, using one of a variety of techniques I still needed to test.

Then I sprued them up: four patterns attached to a central wax post sitting in a printed base cup, ready for investing.

First pour

The first brass pour, a bead of molten metal sitting on top of the plaster investment. We'll see how it comes out, I said.

It didn't come out, but oh so close. None of them was good enough to use.

A homemade vacuum (October 25)

A vacuum would have helped. I tried to rig something up, but couldn't get it to seal, and a proper vacuum setup was a bit expensive. That was not happening without trying something cheaper first

I took another swipe at pouring over lunch, this time with vacuum: a pump with a gauge, a hose to a vacuum chamber, and a plywood platform with a silicone mat holding the flask. I didn't think it worked, because the pressure gauge wasn't showing anything.

But actually, it seemed to have worked pretty well. Not perfect, but maybe good enough.

A proper vacuum caster

That position didn't last long. A vacuum casting machine arrived about a day after I ordered it. This was the turning point in the casting process: with it, investment castings went from okay to spectacular.

Here's the mold after quenching and breaking it open, just before the reveal. The suspense builds.

Victory. A couple of holes that I should have expected, but the detail is great, and I think I can get at least two earrings out of this one.

One more try (October 30)

I wanted to try one more time just to see if I could do it, even though I'd already given her the printed ones and she liked them. I can see a few places where I could improve, but I'm pretty happy with this version. The lines you see here are layer lines from SLA printing - they are maybe 50 microns tall, so the detail transfer is impressive.

These were used to make the final version shown at the top.

Pi Day Earrings

Mon, 14 Mar 2022 00:00:00 +0000

Our family celebrates Pi Day. As part of it, my younger daughter wanted to make some earrings she could wear to school. I modeled them to her specifications, we 3D-printed them, and then spray-painted them. I wanted to cast them in metal, but I was having trouble and we had a deadline, so the plastic versions were what we went with. I think they came out great. She wore them to school on March 14th.

Here's a close-up.

Trying to cast them (February and March 2022)

Here's the wax pattern cast from the 3D print, in blue. Oh hey, it worked.

Then I tried again, with what I thought was a better sprue design. This one is printed in grey resin.

That earring is slightly convex, like a contact lens. I failed many times to cast it in brass and aluminum bronze, but I learned a lot doing it. In the end I just printed it and spray-painted it.

Pi Day 2023

The next year, my younger daughter had another Pi Day earring concept in mind: a sphere made up of the digits of pi. I worked through the math for it in OpenSCAD.

This was the prototype, printed in white resin and coming together a few days before Pi Day. The design is hers.

The finished earrings were done just under the wire on March 14th. I'm not sure why she wanted black, but they are as ordered.

Here's a better picture, after she highlighted the numbers.

Another look at the prototype.

Ring Mandrel

Sun, 19 Apr 2020 00:00:00 +0000

This is another pretty early metalworking project, so it's quite a bit cruder than stuff I would later make. Still: growth, and all that. It worked to hold some rings I was working on.

You screw in the screw at the end and the whole thing expands to grip a ring from the inside, so you have full access to the outside.