Time for fun

Stuff you made and how to make cool stuff

Time for fun

Postby Doug Coulter » Tue Nov 04, 2014 2:11 pm

While I've not been doing much fusor running since our rather dangerous breakthrough 84 e9 neuts/second), but rather doing boring work on making it possible to run remotely...I'm still in the game now that I'm healthy again. There are a couple of peaks in our data we've only seen the rising edges of, and we are still pursuing power - 84 (very roughly, I'll have more on that elsewhere) milliwatts out for a couple hundred watts in isn't quite where we want to be - yet.

One of the places we've only seen the exponential rise in both output and Q is the main HV voltage. I've built (with considerable help from Bill) a much larger power supply for that one - it will go to 100kv+ and more kW than I could ever want (it's actually a little scary and dangerous). That should find the other side of that peak, if indeed it doesn't just keep going up forever.

The other one is grid design, accuracy in particular, but we've also not worked out the ideal size or form factor for this tank. It seems halving the error of the grid considered as a lens about quadruples Q and output both. So the hunt is on there too.
And hence, this picture of things I'll be playing with for awhile.
GridParts.JPG
Grid and tool making parts...


Bill found around 40,000 pieces of very straight Kovar, 18 mils or so in diameter. They are straighter, if shorter, than the tungsten welding rods that are .020" I've been using for awhile. Worth a try.
The real find (Bill again) was .009" tungsten carbide rods, really straight too. These would probably have the lowest secondary electron emission of all, but who knows till we try? Could be the hot D reduces the tungsten carbide back to tungsten.
Either way, they'll be less than half the diameter of what we were using before, but seem still stiff enough to hold up the far end of the grid if it isn't too heavy (I don't make them heavy anymore anyway), so there should be increased transparency with these.

The trouble is, you can't (or I haven't) found .009" drills with 1/8" shanks, as I have for everything else. This means making a new collet for the 1mm shank the drills I found have, instead, and upgrading the toolpost grinder/drill with higher grade bearings (Jerry is often right about this kind of thing, I believe he mentioned this when I first built the one I have). Hence, there are a couple pieces of centerless ground tool steel, annealed at one end, to make new shafts, and some .006" kerf slitting saws to help me make a tiny collet for the tiny drill, which you can't even see the drill part without magnification if you have my eyes. Obviously, we want minimum runout for this, as the drills will break if not. I will still use the new angle jig with the stepper motor to locate the holes - it seems fine, and quite stiff compared to any other force going on while drilling the rod holes. I'll have to try measuring any errors with a good micrometer I suppose, it's way out of caliper range already - perfect as far as one of them says.

One issue that may arise...the welding rods weren't quite round - they were more like 21 mils by 19 or thereabouts. Forcing them into a 20 mil hole in graphite was what held the grids together, and in fact it took some fair amount of force. The new stuff is all as round as I can measure...but I did get a .0087 drill for the WC rods, so it'll be a shave-fit (graphite shaves off in either case as the rod is pushed in).

Looks like the machines and I will be busy around here awhile. Cool! Just doing the remote control stuff was getting really boring (but required to live through this work).
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Time for fun

Postby Jerry » Wed Nov 05, 2014 11:41 pm

Just use a carbide end mill: http://bitsbits.com
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Re: Time for fun

Postby Peter Schmelcher » Thu Nov 06, 2014 1:25 pm

How about 2 or 3 slightly larger diameter rods primarily used for graphite mechanical support and then use 0.001” or 0.003” tungsten wire in tension for the remainder of the lens. I would guess the outer radius of the all the W wires and rods would align for the best lens focus.

I finally fixed my servo amplifier. Initially I received some counter fit SCRs components from an HK/China supplier, a new experience for me. They will label an electronic component with any graphic that gets a sale. Fortunately fuses opened and nothing was damaged other than some pride. I replaced them with real parts from Digikey and everything seems to be working. Live and learn.
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Re: Time for fun

Postby Doug Coulter » Thu Nov 06, 2014 7:00 pm

Thanks for the tip, Jerry, I added it to the vendors section. I will most definitely be checking them out. I did make an adapter for my existing collet/toolpost thing, out of plexiglas. Drilled it .039" from both ends, made an arbor for the 6 mil kerf slitting saw for the same tool post tool - it works! It's a little off - about 1 mil TIR, but that might be because my bearings are getting old (you were right when you told me to get the top grade....they're on the way now). Or could be my shaft is slightly not-straight (plain old 12l14). I have some centerless ground steel shafts to make replacements with, though.

China is a mixed bag. I recently got 10 seeduinos (arduino uno clones) for around $32 including shipping - and even the ftdi chips are real. You have to know your vendors...which can take a few losses along the way.
We do have a place for vendors, I suggest you name and shame whoever it was over there where it's on-topic. If someone cheated you, we all want to know who it was!
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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