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  #1  
Old 05-21-2004, 09:49 AM
Sat on Cookie Sat on Cookie is offline
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Is there a name for that dynamite box thing?

This is possibly the stupidest thread ever, but my brains have fallen out at the moment.

Like, on cartoons when they push down on the lever that's attached to a box and dynamite explodes? What would you call that?
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  #2  
Old 05-21-2004, 09:52 AM
CandidGamera CandidGamera is offline
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I believe, if I recall correctly, it is a "plunger".
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Old 05-21-2004, 10:05 AM
CalMeacham CalMeacham is online now
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I have a copy of Explosives sitting here on my desk, and have looked through it -- I would've thought that it was called a detonator or an initiator, but those terms have specific meanings. Plunger isn't listed.

I always wondered how those things work, and I finally learned at the Museum of Natural History at the University of Utah -- they have a mock-up of an Old West mine, with one of those detonating plungers. The side is cut away, so you can see the guts.

Attached to that handle is a serrated-tooth pinion that meshes with a pinion/gear that's attached to the shaft of a little generator. Pushing down on the handle briskly thus generates a voltage. At the bottom of the plunger shaft is an electrical contact that, when it gets to the bottom of its run becomes the thrown part of a switch completing a circuit with the generator. I couldn't tell if there was anything more to it -- if the direct AC output of the generator triggered the explosion (that would be my guess -- keep it simple) or if it went through a rectifier and into a capacitor to store up a bit charge to be released by that switch.

Nowadays, of course, all you need is a battery and a swich. Construction guys doing blasting probably just use a safety-switched unit with a battery and a switch. I know model rocket guys do. If I'm not mistaken, pyrotechnics experts in the movies use complex boxes that basically control timing of the release of current from batteries or wall voltage.
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Old 05-21-2004, 10:06 AM
Frank #2 Frank #2 is offline
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Quote:
Originally Posted by CandidGamera
I believe, if I recall correctly, it is a "plunger".
This is what I've always heard it called.
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  #5  
Old 05-21-2004, 10:11 AM
Q.E.D. Q.E.D. is offline
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It is a magneto blasting detonator. When you push down the plunger, the rack gear on the plunger shaft turns a pinion gear on a magneto (a type of electrical generator) shaft. The current this produces sets off the primer charge, which in turn detonates the dynamite or whatever explosive you happen to be using.
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Old 05-21-2004, 10:14 AM
Sat on Cookie Sat on Cookie is offline
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WOW. Thank you.*

*this is the best damn message board in the freakin' world
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  #7  
Old 05-21-2004, 10:18 AM
Sat on Cookie Sat on Cookie is offline
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Quote:
Originally Posted by CalMeacham
I have a copy of Explosives sitting here on my desk
P.S. CalMeacham, this just struck me as really funny. I'd ask to have it for a signature, but I think it would be in bad taste these days.
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Old 05-21-2004, 10:29 AM
Philster Philster is offline
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Does ACME have the patent on that?
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  #9  
Old 05-21-2004, 10:39 AM
Master Wang-Ka Master Wang-Ka is offline
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Hm.

"Bugs Bunny Style Magneto Blasting Detonator."

Could we have finally found a replacement for "1920s Style Death Ray?"
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  #10  
Old 05-21-2004, 10:49 AM
Yllaria Yllaria is online now
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Gotta be: "1920s Bugs Bunny Style Magneto Blasting Detonator."
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  #11  
Old 05-21-2004, 11:23 AM
Diceman Diceman is offline
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Rest assured that this is definitely NOT the stupidest thread ever. That dubious honor goes to "Someone told me that a duck's quack doesn't echo. Is this true?" or any variant thereof
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Old 05-21-2004, 11:47 AM
Sat on Cookie Sat on Cookie is offline
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I can't even believe I'm doing this, but I have to ask for clarification. Q.E.D, is the *specific* box you referenced a magneto blasting detonator? i.e., if I was just going to reference it (yes, there is some rhyme or reason to this) would I simply say a blasting detonator or are the *all* magneto b.d.s?
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Old 05-21-2004, 11:57 AM
Q.E.D. Q.E.D. is offline
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Quote:
Originally Posted by Sat on Cookie
I can't even believe I'm doing this, but I have to ask for clarification. Q.E.D, is the *specific* box you referenced a magneto blasting detonator? i.e., if I was just going to reference it (yes, there is some rhyme or reason to this) would I simply say a blasting detonator or are the *all* magneto b.d.s?
Oh no, there are other types of blasting detonators. Some types use a piezoelectric element (similar to the type found in some pushbutton cigarette lighters), while others use a battery and a series of interlock switches to prevent accidental ignition. All of them have the common purpose of ensuring that the charge is absolutely safe until the device is triggered intentionally.
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  #14  
Old 05-21-2004, 12:08 PM
Sat on Cookie Sat on Cookie is offline
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Thanks very much, Q.E.D.. I'm actually using the information in an article I'm writing, so you really helped me out.
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  #15  
Old 05-21-2004, 01:20 PM
Padeye Padeye is offline
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Quote:
Originally Posted by Yllaria
Gotta be: "1920s Bugs Bunny Style Magneto Blasting Detonator."
Unfortunately Bugs didn't appear until Porky's Hare Hunt in 1938. He was a proto-bugs at that as Tex Avery's version didn't hit the screen until '40 in A Wild Hare. You could have a depression era, Bugs Bunny style mageto blasting generator I suppose. I'm sure plenty were used on WPA projects.
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  #16  
Old 05-21-2004, 01:44 PM
BMalion BMalion is offline
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This thread alone is worth $4.95!

Q.E.D., great link.
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  #17  
Old 05-21-2004, 02:25 PM
matt matt is offline
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Quote:
Originally Posted by CalMeacham
I couldn't tell if there was anything more to it -- if the direct AC output of the generator triggered the explosion (that would be my guess -- keep it simple) or if it went through a rectifier and into a capacitor to store up a bit charge to be released by that switch.
The older machines did not have capacitors. As you pushed the plunger down, the magneto was on open circuit and rotational K.E. was stored in the spinning armature, which acted as a flywheel. When the circuit was closed at the bottom of the stroke, the accumulated K.E. of the still-spinning armature was converted to a short-lived, high-power discharge.
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  #18  
Old 05-21-2004, 10:50 PM
hermann hermann is offline
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From my Army days I remember it being called a blasting machine.


http://images.google.com/images?q=tb...my_10cap_2.jpg



(if there is no picture shown, just Google "blasting machine")
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