[Coco] Schematic for external PIA, cart protoboard.

[Gene Heskett]

On Saturday, February 07, 2015 09:26:22 PM Richard E Crislip wrote:
> On Sat, 7 Feb 2015 14:24:00 -0500

[...]

> Talking about milling a solid block reminds me of the day in metal shop
> we were trying to cut down and trim off chunks from a solid block of
> aluminum to melt down in the furnace. It was a struggle but we finally
> got enough off to toss into the furnace. When the furnace hit around
> 1500 degree, the shop teacher realized that our block of aluminum was
> really a block of magnesium 8-). We like to have NEVER got it
> extinguished. It put out a really cool looking greenish-yellow flame
> too. And no one thought to bring the winnies 8-).

You have an idiot for a shop instructor, certified!  You realize of course 
that putting water on a magnesium fire only intensifies the burning about 
100x?  It will steal the oxygen out of the water and make a fine fine show.

I hope the furnace was outside else it could have taken the whole building.

I learned about that the easy way, I was taking lessons on gas welding from 
a guy in Iowa City, circa 1956 or so, who had a card carrier strip folded up 
in his billfold with every welding certification known to the military, about 
4 feet long when unfolded.  

One evening he allowed as how he was going to show us how to weld magnesium.  
With a smith wrench no less.

I thought, yeah sure and made sure I had my sunglasses handy, aka the  
goggles with the #5 ND lenses.  The item in question was a big 6 Mercury 
outboard engine block that had over heated a bit after tossing a rod out 
thru the side & drainig the water.  But he had all the broken mag bits, very 
carefully fit them back into the hole in the side of the block and then 
proceeded to make some really nice beads of mag rod all the way around in 
all, tight enough it should have held water again.  After he had suitably 
impressed the 6 or 7 of us, and discussed the heating technique he used with 
the smith wrench, he then said that it was known that this block was warped 
far beyond an possibility of ever line boring it for oversized bearings. IOW 
it was junk.

Then he said this is what happens when you get it too hot and laid the cone 
of the flame from a #5 tip on a corner of the block.  Took about 30 seconds 
to start the fire.  Knowing he was going to do that is probably why we were 
out on the sidewalk 20 feet from his shop.  When it lit, he advised us to 
stay upwind and just watch the show as he had no way to put it out that 
didn't cost way more than the block was worth.  10 minutes later the Iowa 
City FD showed up with a couple pumpers and a 10k gallon tanker.  We had a 
hell of a time convincing them that the last thing they ever wanted to do 
was put water on a magnesium fire. 

It burned thru the sidewalk which had seen better days 40 years back, and 
about 2 feet into the dirt before it was used up.  So the city comes by and 
writes him a ticket for destroying city property.

It wasn't, it was grandfathered into the land when his father had bought it 
50 years back, but the judge read the city a couple verses from the city 
version of the bible when he arrived in court to fight the fine, he had a 
contract with a local cement peddler to replace that whole blocks worth of 
poor dangerous sidewalk, dated 3 days before the fire, and pictures showing 
the newly laid sidewalk that had already been done by the time of the court 
date.  The judge was duely upset at having his time wasted.

Yup, I have quite a list of BTDT's.

Cheers, Gene Heskett
-- 
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