brass vs bronze for making a punch

On Mon, 25 Apr 2016 08:26:16 -0400, Leon Fisk


30+ years ago I was takeing a "night school" Saturday morning class at the local community college. Since the winter class was held outdoors, we were happy to indulge in the mid class coffee break in the automated caffeteria. One Saturday, the coffee machine refused to co-operate. After I "thumped" it a couple times, everyone had a free coffee an I had over $5.00 in leftover coins!
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On Sun, 24 Apr 2016 21:50:30 -0400, Ed Huntress

It must have been in the mid 1960's.
They also had a "tape controlled" machine there that would do things automatically. It could even change tools, or so I was told. One guy had been to school on the control system but it was never used while I was there.
I did ask the guy how it worked and it used a punched tape like a telex machine. The left column was, say longitudinal travel, and one punch was one increment of movement.
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wrote:

Ah, OK, that fits. Sinker-type EDMs were pretty capable by then, and you could use a quarter, say, as an electrode, to burn the end of a punch or die.
But I think you'd go through a lot of quarters doing it. Tungsten-silver was a premium electrode material, but I think that plain silver would melt off pretty quickly.

Um...that's how I learned lathe programming. We had a Sheldon 1710H controlled by a Bendix 5 NC, and a teletypewriter to key in and punch the paper tape. I could program straight cylinders and tapers, and face them off, IIRC. <g> I never did any actual work with it; the real machinists wanted to play with it and hogged the keyboard.
For anything complex, we used a telephone-connected time-sharing system that did the programming by computer.
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On Mon, 25 Apr 2016 08:48:03 -0400, Ed Huntress

Good Lord! Fifty years ago? I can just barely remember the incident, the details are gone for ever :-)

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On Mon, 25 Apr 2016 08:44:12 +0700
<snip>

Mid 70's... one of my fellow shop class students figured out that he could re-size pennies using the 1 inch vertical belt sander. Schools vending machines took them as dimes. He was caught a short time later working at the belt sander :)
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On Mon, 25 Apr 2016 09:35:47 -0400, Leon Fisk

Imagine doing time in a federal prison for counterfeiting dimes. <g>
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On Mon, 25 Apr 2016 09:47:39 -0400

After reading John's story I wonder if the pennies material helped it to be accepted. Some of those machines had pretty innovative means of detecting real coins. The thing that tripped the kid up was using the schools shop equipment. If he could have done the work elsewhere it would have taken a lot longer to catch him.
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On Mon, 25 Apr 2016 09:54:34 -0400, Leon Fisk

At another base one of the guys tried turning coin sized blanks for the Coke Machine. It didn't work either but somehow one of the machined blanks got stuck in the machine and the Coke Machine Guy went to the Squadron Commander and a great investigation ensued... "My guy made a fake coin" Nah, couldn't be, none of them drink Coke".
But it did appear that a Coke machine was a bit "smarter then the average bear", to paraphrase Pooh.
A far better scheme was discovered by "one of the guys" while TDY to Okinawa to support the "Black Birds". In wandering around he discovered that the Jet Engine Shop had bins of some sort of "bronze" nuts that could be bored out to finger size and when machined and polished a bit looked surprisingly like a gold ring. Subsequently he discovered that the "ladies" in the pubs would trade their services for gold rings.
He said that if he had any more spare time to make rings he probably would have "died in a foreign land" :-)
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On Mon, 25 Apr 2016 09:47:39 -0400, Ed Huntress

We used to dip clean pennies in mercury and pass them as dimes with local merchants
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On Mon, 25 Apr 2016 19:55:41 -0400, snipped-for-privacy@yahoo.ca wrote:

Oh, right...you're a Canadian. They had to put facets on your nickels to keep you from shaving them on those long winter nights. <g!>
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On 04/24/2016 8:12 AM, John B. wrote: ...

Can't help but wonder what size these would've been and who was the customer? All except the most unusual would seem to have been bulk items long before then...

...
JC Penney paid my (then future) wife in cash in $2 bills and change every week in those days, too, when J. C. himself was still around. In his 90s, he remembered meeting her in the hometown store a couple years earlier when visiting the store in Manhattan where we were in school at the time and she worked in that store...while not metal-working, there were metal coins in the pay envelopes... :)
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It was a LONG time ago but as I remember it they were normal sized nuts. Nothing that you couldn't buy off the shelf in the local hardware store.
But "back in the day" apprentices did not argue with the Boss, so I never asked :-)

:-)
I was stationed at an airbase near Selma, Alabama and the local folks didn't appreciate the Air Base people at all. The Base Commander arranged for us to be paid in 2 dollar bills and silver dollars one payday. There was a noticeable warming of the town's attitude toward us thereafter.
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On Sunday, April 24, 2016 at 8:49:03 AM UTC-4, Ed Huntress wrote:

Sorry about that, but I and Cydrome Leader both remember mil as being the same as a thousandth. We are not all as young as you.
Dan
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On Sun, 24 Apr 2016 09:06:12 -0700 (PDT), " snipped-for-privacy@krl.org"

You know, I knew some old fart would pop up with that, as soon as I wrote it. <g>
What I should have said is that it all but disappeared in *print*. It migrated over to the sheet-material field, where it eventually became concentrated in plastic materials. I wrote a few articles for _Modern Plastics_ and _Plastics Technology_ (on moldmaking) in the '70s and '80s, and I noted it was being used by them.
I've seen it used for sheet metals, too, but only very rarely.
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On Sunday, April 24, 2016 at 12:06:15 PM UTC-4, snipped-for-privacy@krl.org wrote:

I do too, but that was in a shop that was run by people well into their 70s, back in the late 1970s.
The problem was that mil was used universally for thousandth of an inch, millivolt and milliamp.
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I've been trying to figure out where I learned mil from. While I do have an electronic-ish background, it's not really a unit you'd use when repairing something. It's likely from an an older designer or engineer friend.
Circular mils are still common enough when it comes to electrical guages, such as a 500MCM cable, even though that's sort of a weird unit- "thousand circular mils." Pretty sure that's the same as a 1/2" copper rod.
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On Sun, 24 Apr 2016 19:57:48 +0000 (UTC), Cydrome Leader

A circular mil refers to the cross-sectional area of a wire with a diameter of 0.001 inch. The formula is A = d^2, where A is the area in circular mils and d is the diameter of the wire in mils. So a 1/2 inch rod is 250,000 circular mils.
It keeps you from having to use pi to calculate the cross-sectional area of a wire; if you know the current-carrying capacity in circular mils, you just use the A=d^2 formula to calculate the current-carrying capacity of a wire of any diameter.
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On Sun, 24 Apr 2016 19:57:48 +0000 (UTC), Cydrome Leader

You sure about that??? Comes out to more like a 3/4 inch copper rod (actually 0.8" diameter)
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snipped-for-privacy@snyder.on.ca wrote:

Not completely sure at this point- and it looks like there are three ideas as to what 500MCM cable is equivalent to if it was just a rod. May have to look this one up.
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    [ ... ]

    Depends. Back as late as the 1970s, I would commonly see the term "mil" used in integrated circuit data sheets -- for things like the spacing between pins on a given side (typically 100 mils), and the separation between two rows of pins (for common TTL ICs, typically 300 mils -- though some were larger, 400 mils, 600 mils and such). The same units were used for the dimensions of the bodies of the chips, between the pins, too. So, the term stuck around for a while longer in certain industries.
    Now -- the surface mount chips -- with rows of ribbon leads soldered to a single surface of the board were 50 mil centers back then, though smaller now, I believe.
    I don't have any recent data sheets ready to hand, so they may have changed since then.
    Enjoy,         DoN.
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