DIYbanter - View Single Post - FA: Dumore Tool Post Grinder Inserts, K.O. Lee Index Disc and other metalworking items on Ebay

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

[ ... ]

Right. Now, Ill have to get a big enough lathe.

O.K. Good luck with that. I've been known to collect
accessories when I could, in hopes of acquiring a machine with which
they could be used later.

But did you inherit a tool that caused lathe acquisition?

Not a chance. The only tools which my father had were a couple
of tiny claw hammers with at least one claw broken off each, two very
rusty screwdrivers, and eventually an electric drill with a circular
sanding pad for work on the boat.

I was the tool user in the family. My father, and his father
were both lawyers (and later, a judge, for my father).

My father has a reasonable number of tools, but he is no machinist.

A bigger issue is how fast the tube deionizes. If it isn't fast enough,
one cannot flash the tube fast enough, as it stops flashing and instead
remains always on. Deionization time is mostly determined by flash
tube
design.

This may be one of the reasons for the internal trigger
electrodes, and the extra volume (of unionized xenon) to quickly replace
the ionized stuff.

Exactly. It's the nearby masses of metal that does the job.

That -- and perhaps the greater volume of Xenon surrounding the
arc path?

Not unless it's moving. Ions diffuse too slowly.

If it does not deionize quickly enough, and the capacitor
charging current is high enough, it will indeed remain on full time.
Part of the problem is the deionization time, part is the voltage to
which the tube discharges the capacitor.

Edgerton's book "Flash, Strobe" goes into the details of how the
Strobotac and allied devices work.

O.K. Do you have access to that book? I've never seen it --
though I have met and talked to the man. Is it still in print?

Bought in my copy in 1983: "Electronic Flash, Strobe", 2nd edition,
Harold E. Edgerton, MIT Press, 1979, 366 pages, ISBN 0-262-55008-3.

I looked on Amazon.com. There is a 3rd edition, with used copies going
for ~$120.00. Ouch! I had no idea. It must have become a classic. My
copy of the 2nd edition cost $10.00 new. No mention on Amazon of
anything other than the 3rd edition.

There are a lot of patents listed in the back of the book. I bet the
theory is described there. I'll look. The application notes from the
various flashtube makers aren't too bad, but the book pulls it all
together.

I wonder if there are any other textbooks in print. I have not heard of
any, but wasn't looking.

The best online source I know of is Sam Goldwasser's electronic repair
website, and his bookmarks:
http://www.eio.com/repairfaq/sam/sambook.htm. Look down the list the
the section titled "Strobe/Camera Sites/Information" about 3/4 of the
way down.

I have a question in at Perkin-Elmer asking if the FX-6A is still made,
and if not what is it's replacement (perhaps Series 1100), and what
they
cost. We shall see.

O.K. Good luck.

So far, no response.

Sigh!

[ ... "Electric Brazing" ... ]

I saw that one. Never heard of the company.

Nor did I. But it looks like one of the wartime unknowns which
got contracts to make a product known to come from a larger company --
simply because they could not turn them out in the quantities needed.
I've seen Tektronix scope clones made under such contracts -- they
looked almost identical to the Tektronix, other than the maker's name.

Yes. Don't know how good a job they did.

Nor do I -- but they had to match the specs or they would lose
the contract. And they *should* have had copies of the GR prints and
schematics for the purpose. The lack of a large "crystal" dome over the
soupbowl reflector may have been a part of the money-savings and
material savings during wartime.

They will have had the full manufacturing documentation set.

O.K. Part of the problem, of course, is stability of the
timebase. A really good one could be made with a crystal oscillator, a
bunch of counter chips and comparators -- load in a count (period, not
frequency) and it would be very stable. Even the nice little GR
Strobotac which I have drifts for the first minute or so. And that one
is solid state. The older (soupbowl) one takes longer to stabilize, and
it is run from tubes.

Yes. The strobe I built is triggered by an optical encoder on the
winder's main axle, so the image stands absolutely still as the rotation
rate is varied.

Any idea what the maximum flash rate was?

I designed it for 20 Hz (1200 rpm) max, have run it at twice that
without difficulty, although the flash energy is too high to run at that
speed for long without overheating the flashtube. It's easy to fix (use
smaller flash capacitor), but I haven't bothered yet.

The tube I designed for is the Xicon unit sold by Mouser for timing
lights (361-4425) and the trigger transformer (422-2304). The max flash
rate spec (60 per minute) is for the max flash energy (4 Joules/flash).
One can go faster if one respects the power limit, 4 watts average. I
don't know the deionization limit to speed, but have flashed a Mouser
36FT106 (what I could get at the time) at 28.14 Hz (1,688 rpm), and the
limit is the circuit not the tube. Given that the Extech strobe unit
goes to 10,000 rpm (167 Hz), it should be possible to go far higher.

Joe