Wild_Bill wrote:
Great video presentation, much better than any episode of the How It's
Made TV show that I've seen.

I'll second that opinion...

Fire, and lots of shop-made metal parts to be observed. Resistance spot
welding and induction heating, too.

It looked as though the equipment he was using was all shop-made, and at
the end of the video, it shows the guy making parts in a well equipped
machine shop.

FWIW, and contrary to popular belief, contained vacuum doesn't have to
be performed by using a vacuum pump.
When a vessel is heated to a high temperature, it's fairly well
evacuated of air. Sealing the vessel/envelope while it's hot can be
performed fairly easily when the envelope is glass, whether it's a small
vacuum tube or a CRT.

A simple grade-school demonstration in the early 1960s involved dropping
a small burning piece of paper into a milk bottle, and placing a
hardboiled egg on top of the opening, as the flame went out.

The egg was sans shell as I recall.

That was a time when milk came in a heavy reuseable bottle with a large
neck.
Of course, this didn't demonstrate the evacuation process by external
heat, it was just fun to see.

I also remember the teacher collapsing (imploding?) a gallon tin can
with condensing steam by screwing the cap on the can after boiling a
little water in it.


WB
.........
metalworking projects
www.kwagmire.com/metal_proj.html


wrote in message
...

Pretty interesting vid if you have about 17 minutes to kill.

http://blog.makezine.com/archive/200...ccum_tube.html

Dave



Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.