Thursday, February 20, 2014

Circular Motion

Reserved a lathe today and spent four hours on it.

First task was to put a live center on the piece I'd faced the other day. Which I hadn't been trained on (I assumed it is covered in Class #2: Work Holding and Feed Rates). Faced the piece clean again, set up and used a center drill, and then popped a live center in the tailstock. 

Then made several poor passes, until between tightening the center, re-grinding the tool bit, and going to a higher speed and a slower feed, I started getting smooth cuts -- and good chips, which I was especially looking for. I even got an acceptable surface when hand-feeding.

Took the stock down to the rim diameter for the grenade, then re-arranged things to cut up to a clean shoulder. Then the final thing I had time for was to set up a parting tool and cut the first of the decorative grooves.

I've now gotten over my confusion on which lever does what, and I practiced for a while on a powered-down lathe until I could throw on and off headstock power and crossfeed/carriage feed without any risk of slamming the thing into reverse unexpectedly.

I'm realizing that I probably should have stuck less out of the chuck, and detailed the nose (which has deep cuts and a convex curve) before taking the body diameter down. But that is an expected learning process; as I get used to the lathe (I never want to be "comfortable," not with a tool that can pick you up and spit you out in the blink of an eye), I learn more about how to properly plan a job.

Which was really what this project was about. It isn't like I particularly need an M40 grenade prop. Although it is a cool prop...!

(I also got a real aluminium Snap-Cap to look at and measure. My estimated dimensions are just slightly short of that, close enough that I'm willing to bet that particular Snap-Cap is the right dimensions for the original prop. And that means my drawing should be adjusted a little.)

But now I'm not sure whether I should run in again and keep working with the tools I have, or sent in an order for some blank tools from McMaster-Carr so I can do the next shaping stages properly. It isn't like there is a deadline on this project. It is just that I am so hooked on lathing at the moment I can't seem to concentrate on other things.

The Holocron got a second coat of paint. Krylon Hammered Finish is cool stuff, but it is finicky about how you apply it. Go too light and you don't get the texture, go too stop-and-go and you get annoying little strings, but go too heavy and it lumps up like all too-heavy paint jobs.

Laser-cut an acrylic "spider" to support the circuitry in the center of the cube, and slowly building the final wiring around that (with lots of double-sided mounting tape). Have no idea what the "behavior" is going to be; that will have to wait until I see how sensitive the sensors are.

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