Thursday, May 13, 2010

slowly I milled, inch by inch, step by step

Nah, doesn't have quite the same ring to it as "slowly I turned..."

I have managed to put in at least one hour of work per night on the Mad Scientists Light Switch - among other things - since my last post.

The work I'm doing now is a bit fiddly, but the outcome will be the first noticeable (to an outside observer) progress on the thing in months - something very visible.

By the end of the weekend, I ought to be done with the mounting arrangements for the Jacob's ladder, and should have moved on to the final machining, drilling, and tapping, in the base of the Jacob's ladder tube.

I obtained a second "beer sign" NST (7.5kV @ 15mA) from my friend John, and very soon I need to check whether there is room for two of them plus the control electronics. I'll be terribly disappointed if I can't fit two of them in there, because most likely, it won't work without two. With a single NST of this size, there just isn't enough current to heat the arc sufficiently to make the damned thing work.


Meanwhile, I have the phenolic slab back on the surface plate, with the ends supported by a pair of parallels (flat), a heavy weight (120mA 15kV NST, weighs about 100 pounds) in the center, and two heat lamps warming the whole shebang.

Measurements taken yesterday suggest that the current method is working, albeit slowly. I'm going to give it a full week and measure again. Once I think I've got that piece in the ballpark of "flat", I'll let it sit for another week to see whether it "relaxes" into its old shape.

After that, I'll know whether I want to continue on that path, or just say "fuck it" and mill the thing flat. At least I know now that the latter option is a perfectly reasonable one.

I can't recall whether I've mentioned this before, and I'm too lazy to look, so...

I have a pair of copper bus bars which are perfect for the size of launcher I'm working on. Well, their cross section is perfect, if their length is a little shorter than I'd like. They're roughly 0.75 x 0.5 x 24" or so. But the price was right. The only problem with these rails is that they were previously bus bars, and whoever made them drilled several .25" holes through the thickness. My plan is to ream these holes out to a precise diameter, turn some dowel pins out of 110 copper to a diameter about .002 larger than the holes, and heat-shrink the pins in the holes. I'll order the reamer I need for this operation next pay day. Need to remember to order a few replacement drill bits too...

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