Official Luthiers Forum! :: View topic - Big Bertha And Why We Leave Pick Wear Alone At Times

In the early 80s, I was working on mainframe computer hardware. A common disk drive of the day was a 300MB (huge at the time) CDC drive that used disk packs of nine platters each--looked like a cake holder. When in operation, it shook like a washing machine. The permanent magnet part of the servo that moved the heads over the disk platters was huge. Great for magnetizing screwdrivers, and when scrapped great for fishing stuff out of lake bottoms. But it was the voice coil on the actuator that ran within that big permanent magnet that was the really dangerous magnetic device. If at any time the drive's logic detected a loss of signal from the servo head (one disk surface was the servo surface, and it had timing marks that let the machine know what track and sector it was on at any given time), the machine would perform an "emergency retract." A bank of huge capacitors would let loose on the voice coil, and it would move really really quickly off of the disk pack. Many technicians lost fingers when working on these machines. Magnetism is a powerful force!

Dave

And separate computer rooms too with raised floors and cable trays overhead, those were the days. We would run our card decks.... RPG II in the middle of the night and interactive computing was not yet common but batch processing was.

Now my SSD that I use to load my 62 MP Sony camera pic has more storage than that entire room and fits in the palm of my hand.

There seems to be a natural migratory path for ole mainframe guys to Lutherie at least in this thread.

Terry thanks for that you know I should put up signs that we have magnets in use for people with pacemakers, good thought. Our clients can't come within 10 feet or so of the magnets but sometimes they get away from us because of the historic nature of our shop they start to wander.

None for me, thank you. I have some metal clips in there from my vasectomy.

It’s an interesting progression that a bunch of old guys (no offense intended) are telling “back in my day” stories about computers. I remember a time when old guys swapped stories about the days before there were computers.

Author:	Hesh [ Tue Jun 14, 2022 8:17 am ]
Post subject:	Big Bertha And Why We Leave Pick Wear Alone At Times
Two currently running threads here were asking about using rare earth magnets and how to repair some pick wear on a guitar top. We've been using rare earth magnet taking the place of clamps most of the time now and we've been doing this for well over a decade. Wanted to show some pics of who we call "Big Bertha." Dave Collins came up with this and both faces are potted in teflon so glue will not stick. This one can lift over 300 pounds and we stopped there not having anything heavier except for my Honda Also look at the pick wear. This guitar is not with us for pick wear, the owner wanted some loose braces and a crack repaired and that's why we have it. You have likely heard this guitar before and that's all I'm going to say about this. Anyway it's a beautiful old Gibson "player" and it has character for days. People with guitars like this one will not be asking us or you generally speaking to repair the cosmetics and instead see the war wounds as a rite of passage and a ticket to ride with the big boys/girls. Back to the magnet, because of he raw power (and danger...) here Dave has it in a case that has a crank to lower the magnet's together and the crank was also required because we can't pull them apart, the force required is beyond what any of us could muster.

Author:	joe white [ Tue Jun 14, 2022 12:04 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
Having been pinched by some nickel sized magnets I keep around, I can only imagine the damage big bertha could do. Oh, and that's a beauty of an old Gibby.

Author:	Terence Kennedy [ Tue Jun 14, 2022 12:46 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
That is frightening. Stay away from pacemakers or cathode ray tubes. Back in the early 70’s I worked with a heart surgeon and when we put in a pacemaker there was a big blue really strong magnet that came with them. They were for triggering switches through the skin after they were put in. I’d take the spares home for the kids to play with. Once they tried to stick it to our little TV. The screen wound up looking like a tie dyed tee shirt.

Author:	Jim Watts [ Tue Jun 14, 2022 3:22 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
That's a really good way to keep yourself safe, while not destroying the guitar. Good job guys!

Author:	ballbanjos [ Tue Jun 14, 2022 4:01 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
In the early 80s, I was working on mainframe computer hardware. A common disk drive of the day was a 300MB (huge at the time) CDC drive that used disk packs of nine platters each--looked like a cake holder. When in operation, it shook like a washing machine. The permanent magnet part of the servo that moved the heads over the disk platters was huge. Great for magnetizing screwdrivers, and when scrapped great for fishing stuff out of lake bottoms. But it was the voice coil on the actuator that ran within that big permanent magnet that was the really dangerous magnetic device. If at any time the drive's logic detected a loss of signal from the servo head (one disk surface was the servo surface, and it had timing marks that let the machine know what track and sector it was on at any given time), the machine would perform an "emergency retract." A bank of huge capacitors would let loose on the voice coil, and it would move really really quickly off of the disk pack. Many technicians lost fingers when working on these machines. Magnetism is a powerful force! Dave

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Author:	Casey Cochran [ Tue Jun 14, 2022 4:13 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
None for me, thank you. I have some metal clips in there from my vasectomy.

Author:	Jim Watts [ Tue Jun 14, 2022 6:01 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
ballbanjos wrote: In the early 80s, I was working on mainframe computer hardware. A common disk drive of the day was a 300MB (huge at the time) CDC drive that used disk packs of nine platters each--looked like a cake holder. When in operation, it shook like a washing machine. The permanent magnet part of the servo that moved the heads over the disk platters was huge. Great for magnetizing screwdrivers, and when scrapped great for fishing stuff out of lake bottoms. But it was the voice coil on the actuator that ran within that big permanent magnet that was the really dangerous magnetic device. If at any time the drive's logic detected a loss of signal from the servo head (one disk surface was the servo surface, and it had timing marks that let the machine know what track and sector it was on at any given time), the machine would perform an "emergency retract." A bank of huge capacitors would let loose on the voice coil, and it would move really really quickly off of the disk pack. Many technicians lost fingers when working on these machines. Magnetism is a powerful force! Dave I used to use those storage devices myself!

Author:	SteveSmith [ Tue Jun 14, 2022 9:19 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
We had racks of RA-60’s Steve

Author:	Hesh [ Tue Jun 14, 2022 11:18 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
And separate computer rooms too with raised floors and cable trays overhead, those were the days. We would run our card decks.... RPG II in the middle of the night and interactive computing was not yet common but batch processing was. Now my SSD that I use to load my 62 MP Sony camera pic has more storage than that entire room and fits in the palm of my hand. There seems to be a natural migratory path for ole mainframe guys to Lutherie at least in this thread. Terry thanks for that you know I should put up signs that we have magnets in use for people with pacemakers, good thought. Our clients can't come within 10 feet or so of the magnets but sometimes they get away from us because of the historic nature of our shop they start to wander.

Author:	ballbanjos [ Wed Jun 15, 2022 5:38 am ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
Hesh wrote: And separate computer rooms too with raised floors and cable trays overhead, those were the days. We would run our card decks.... RPG II in the middle of the night and interactive computing was not yet common but batch processing was. Now my SSD that I use to load my 62 MP Sony camera pic has more storage than that entire room and fits in the palm of my hand. There seems to be a natural migratory path for ole mainframe guys to Lutherie at least in this thread. Terry thanks for that you know I should put up signs that we have magnets in use for people with pacemakers, good thought. Our clients can't come within 10 feet or so of the magnets but sometimes they get away from us because of the historic nature of our shop they start to wander. Yep, those old batch processing days were something. One Sunday morning in the late 1990s, long after we had done away with using card readers but still had one in the computer room, we were in the process of migrating the rest of our mainframes programs over to UNIX, our mainframe crapped out. And it crapped out good--none of the usual methods of communicating with the computer worked. It dawned on us that the card reader was connected to the computer at a much earlier and more primitive point in the circuitry, so it was worth a shot. But we had no card punches any more. I called some friends who worked at banks where card punches were still in use (they used them as part of the proof/sorting operations to feed info back into the mainframe). So here we are nearly into the 21st century desperately seeking a card punch??? Well we found one, I punched a deck of cards with machine language code (we called it "primitive instructions") that would tell the mainframe how to find our console and what to do with it once it was found. Triple checked my cards--to opportunity to repunch a boo boo. Anyway, it worked and we were back up in business within a few hours. Back to lutherie though--building and repairing guitars and amps is actually what got me into the IT world to begin with. I was managing a small music store and doing repairs as well as building in my off hours, and decided I needed a better job. Having already used the skills in repair work, I went to tech school in electronics and landed a job as a mainframe repairman. Over the years my role in IT expanded to cover about anything you could do in the field. It was a lot of fun, but I'm glad to be retired and back to building instruments again! Dave

Author:	SteveSmith [ Wed Jun 15, 2022 6:01 am ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
We had stand-alone VAX 11-780 and Micro VAX systems we used to analyze flight test data. I could do it all on my Mac now. Steve

Author:	Brad Goodman [ Wed Jun 15, 2022 10:39 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
Casey Cochran wrote: None for me, thank you. I have some metal clips in there from my vasectomy. TMI

Author:	doncaparker [ Wed Jun 15, 2022 11:15 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
It’s an interesting progression that a bunch of old guys (no offense intended) are telling “back in my day” stories about computers. I remember a time when old guys swapped stories about the days before there were computers.

Author:	Hesh [ Thu Jun 16, 2022 6:05 am ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
doncaparker wrote: It’s an interesting progression that a bunch of old guys (no offense intended) are telling “back in my day” stories about computers. I remember a time when old guys swapped stories about the days before there were computers. There is a famous video that Rod True originally posted on the OLF back in 2006 I believe (what a memory I have and for a pot smoker too) about the "nut bra." Go to Youtube and search on nut bra or hell I'll just post a link now https://youtu.be/1zdDfQrPi5Q

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Author:	Mark Mc [ Fri Jun 17, 2022 8:40 pm ]
Post subject:	Re: Big Bertha And Why We Leave Pick Wear Alone At Times
For a really big and powerful magnet look at a MRI scanner. The magnet is always on and there are strict protocols that prevent any ferrous metal objects coming into the vicinity. There have been fatalities caused when people have rushed into scanner rooms during emergencies carrying a fire extinguisher or wheeling a metal "crash trolley" only to have those big objects become flying projectiles hurtling towards the magnet.