I was like, oh great, I’m going to save tons of money! While the 1″ bar stock of titanium was a steal at less than $200 for a four foot bar, the number of hours I’ve put into the project, even at a monkey’s wages, has pretty much rendered the entire project moot. The folks as Supra Alloys in southern California were very friendly and have good prices on bar stock. But, I do have something to show for it!
For those of you who don’t know, a metal lathe is the exact same thing as a wood lathe. The idea is a machine holds on tightly and spins the stock. You move a “tool bit” around to scrape off bits of metal making something round. You can make a screw, ring, engine parts, many many things. You can get brass, aluminum, steel, or high grade titanium. The sky is the limit there too. With a real hard metal like titanium, you’ll spend more time sharpening the tool bit through, whereas brass, by comparison, is like lathing a bar of soap.
lathes come in many shapes and sizes. These shots are not instagram, they are literally scans of old timey machinists using lathes to make big diesel engines for ships. Pretty interesting stuff.
I decided to make the first couple of rings out of stainless steel as it was sitting around the machine shop and I could just borrow some of it. Stainless turns our real nice. After coming off a lathe, the rings have a matte look to them due to the tool bit scraping up the sides, or the filing taking down the edges. As the ring is still on the bar, and not yet cut off, you can make the outer corner of the ring look perfect. Use a combination of emery cloth (glorified cloth sandpaper) and a nice file to make the outside edge and inside edge nice
and friendly to a human finger. In this shot I’m including you can see the spinning lathe head, the titanium bar stock with the OD cut, and the tool bit in it’s chuck. For this part I’m facing off the end. The tool bit starts in the center of the piece, then slowly feeds from the center to the outside. This leaves a real purdy surface to drill into.
So once you’ve got the ring’s OD lathed down, you drill the center. The drill bits tend to burn up because they’re made of high speed steel, whereas my bar stock is titanium and quite a bit harder than the stock. I would just alternate between drill bits to give one some time to cool off between cutting. Once I cut the ring off, I had the right sized ring with one pretty side, and one not so pretty side. Enter mandrel trick. I didn’t take a good picture of the mandrels that I made but basically they’re chunks of brass whose OD is cut to a few thousandths of an inch less than the ID of the ring in question. I would then drill a hole, and tap (to screw a cutter into a hole that makes threads) it only half way down. Then I pulled that brass out of the lathe, and cut an X in it with a hack saw. The picture of the mandrel above is the basic idea. I would put the ring on the mandrel, and start forcing a set screw into the hole. This would make the four cut parts of the mandrel expand and hold that ring from the good side so that I could spin it and work on the outside OD and ID to make it nice.
So at this point I’ve got a round ring, with offset ID. On one half of the ring, there is more “meat” which is where I cut the lego nubbin into. I rotated the ring 90 degrees, and was able to get it centered up in the four jaw chuck again. This is also where I wish I would’ve done a better job. The ring was as close as I could eyeball it, which was off about 1/20 of an inch or so. When I rotated the ring on it’s side, I was able to start cutting around to make the lego nubbin all by itself on the fat side of the offset ring.