The Secret Lives of Electrons

It’s not much of an exaggeration to say that electrons form the backbone of the modern world. They are our workhorses—they bring energy from power plants to our homes and factories. They are our couriers—they carry information through circuits in our computers. Some day, they will be our providers—as the central elements in photovoltaic solar cells, they will capture the sun’s energy for our use. These current and future electronic devices rely on very precise answers to the question What do electrons do inside materials? Out of technological need and intellectual curiosity, condensed matter physicists have spent over a century discovering better and better answers—and they continue to do so today. In this post, I will try to give you a little glimpse into the form, beauty, and utility of such an answer.

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The Machine Shop

Using the machine shop is one of the best things about working in an experimental physics group. I love the machine shop! Words probably cannot describe its awesomeness, but I’ll try anyway: grinding tool bits is like meditating. Using the lathe to peel away an oxidized surface—thereby revealing the shining fresh metal underneath—is like magic. Everything is sharp, weighs alot, and/or moves fast. And successfully finishing a complicated part brings supreme satisfaction.

Speaking of that—I just finished a complicated part! It’s a phosphor bronze flip stage for a new ARPES sample manipulator. (I realize that doesn’t mean anything to most people, but I’m including its name for completeness.) It took me a few weeks to complete. (And I couldn’t have done it without a lot of help from Nate, Supreme Machinist and Overlord of the Graduate Research Shop.) I’m really excited and want everyone to see it! So here it is:

The colorful areas are regions of oxidized bronze. I didn’t thoroughly clean the oil off my part at one point, and after sitting around for a few days, the surface started to oxidize. The lines on the bottom are marks from the CNC that I used to mill out the protruding rectangles. The circular scratches around the central hole are from a Brillo pad.

Here are a few shots from the machining process. The first shows the CNC in action, milling away the bottom of my part. There’s a long bronze chip stuck to the cutter, spinning around.

Here’s a cleaner version so you can see what the CNC did. Isn’t it pretty?

This shows my method for holding the part when it got too thin: I had to bolt it to an aluminum block. In this picture, I have used a thirty-degree parallel to hold the part on an angle.

Finally, if you’re interested, here’s the entire process of what I did to make the part:

1. I got a stock bronze cylinder.
2. It was too big, so I had to cut down its length. First I used a band saw, then I faced off the uneven cuts with a lathe to make sure the ends of the cylinder were parallel.
3. I then made it into a box. I made rough cuts with a band saw, then used a mill to ensure all the faces were parallel/perpendicular to each other.
4. A drilled a few holes on one end using the mill.
5. I held the part in a four-jaw chuck on a lathe and lined up the largest hole with the lathe’s rotation axis. Then I turned down the box into a cylinder.
6. I flipped it upside down and made a few more holes with a CNC.
7. I used the CNC to remove material around a few rectangles on the bottom.
8. It might be hard to see in this picture, but I used the CNC to make a small counterbore at the end of the protruding cylinder.
9. I cut away a large piece of the box to leave an “L” shape.
10. I milled away part of one end.
11. It might be hard to see in this picture, but I angled the sides. This necessitated turning the whole mill head by fifty degrees.
12. I made another small counterbore on the other side of the protruding cylinder.