Steve said:
>Option B might be using two pieces of wood with a 1/8" hole between the
>split and space the wood apart a bit and use that as a guide for a thin blade
>hacksaw, just wrap the rod with some tape to keep it snug in the wood.
Yes, that's a variant on what I tried when I bust the slitting saw. The slitting
saw is a 3 inch diameter circular saw, 1/64 inch thick. Mounts on an arbour in
the vertical mill, allowing the whole lot to be held very rigidly, but
apparently not rigidly enough. My hacksawing isn't really accurate enough to do
the job nicely by hand, though.
When you make the first cut, looking on the end of the rod you have what looks
like two D shaped pieces, facing each other. Then the trick is to cut
horizontally through the two D's, but the weakness led to the rod breaking. I
figure filling the gap with solder might cure that problem. It's also, I think,
a good idea to turn the taper before cutting the slots. Anyone who looks at the
socket on a Bird and its connection to the main through line can see what I'm
attempting to do - straight 'instrument making', we used to call it!
Anyway guys, thanks for all the suggestions. This project has benefited from
advice given here over quite a period - Jon Ogden as far back as June 99
provided info on the threads on N and UHF types. I knew buying the tap and die
for those threads would prove a useful investment!
The electronics was the easy part, even though the use of 741 op amps rather
than single supply ones that go down to 0 volts input complicated things - but
the 741s were in stock, as was the 555 for the charge pump to produce the
negative line, and the transistors for the negative regulator, and so it was
very cheap!
The holes proved less of a problem, once I used a bit more speed on the tank
cutter (US: circle cutter). The one I've got was $5 or so in Sears, and works
really well, even on 1/4 inch thick aluminium plate. These were B holes though,
as A holes are restricted, apparently, to their natural habitat in Washington
DC.
OK, I now know what a Dremel tool is. I've seen them under other names, and as
was said, all the accessories cost a fortune. I suspect that the milling machine
can do everything the Dremel can, except be carried in one hand!
At least with all this machining, I don't need third party inspection on design,
certification of materials and third party testing as I would if it was model
loco boiler!
73
Peter G3RZP
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