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prometheus1970
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Cap design
The other day I finished another Ag2C2.AgNO3 DS synth. This time I put it all away properly so no accidents while testing. I put together a cap (of
my own dubious design) consisting of .75 gram of ETN in the end of a disposable razor handle, 2 grams NC on top of that. Then I put .2 grams of DS
into an empty .22 shell and put fuse in there and crimped the open end shut. I even thought to cover the part of the fuse inside the plastic handle,
but outside the .22 brass with al duct tape to prevent sparks from igniting the NC (thus bursting the cap before det). Tomorrow I'll test another
identical.22 initiator (just the shell with DS and fuse) to see if the primary will rupture the ass end of the .22 casing thus transferring maximum
energy to the nitrocellulose. Also I sealed the fuse/.22 initiator into the handle with A-B epoxy. I wonder if only the DS detonates, if that will
provide sufficient energy to initiate something like ANNM/Al after having to go through the plastic handle. What do you think guys? Viable, or
should I just stick with DS wrapped up in tape with fuse(or even something else)?
[Edited on 2-8-2011 by prometheus1970]
[Edited on 2-8-2011 by prometheus1970]
Just because you're paranoid doesn't mean everybody isn't out to get you.
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gnitseretni
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I'm not following your design but it sounds like your over complicating things.
Just get a piece of tube. Crimp the end shut or use epoxy. Press ETN in first, then your primary. Stick your fuse in the primary and close it with a
little epoxy (or VERY carefully crimp it- but I don't recommend it). I think some folks use a little black powder on top of the primary. I'd keep it a
simple as possible, but you can get as fancy as you want.
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SB15
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I don't understand the fascination people have with metal caps. With a decent primary, there is no need for anything more than a thin plastic tube; a
.22 casing or crimped metal tube only creates additional shrapnel danger.
A compound cap is a simple device. Cut a plastic straw to length and seal one end with hot glue. Press in your base charge with a wooden dowel. Press
the primary directly on top using the same dowel. Insert a fuse/e-match and seal the remaining end with hot glue. Done.
[Edited on 2-8-2011 by SB15]
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prometheus1970
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I thougt of the shrapnel issue, but I thought that if, immediately upon detonation the metal cap causes detonation of the main charge, wouldn't the
inward-directed pressure of the secondary explosion force any shrapnel back towards the center of the explosion? I know this theory is half-baked at
best, but I would like some feedback.
Just because you're paranoid doesn't mean everybody isn't out to get you.
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gnitseretni
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He recommended a plastic tube for safety of handling. Once its positioned in the main charge, worry about the main charge, NOT the cap 
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mnick12
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Well shrapnel tends to fly in ever direction now matter how the explosive detonates. In an ideal world when one detonates an HE mixture one should be
far enough away that there is no possibility of being hit by shrapnel. Also keep in mind that if you are detonating your mix on or in dirt there is a
good possibility that any rocks will be become shrapnel. Also for det caps, you will rarely need more than .75gr of total explosive(s) in your cap
unless you are dealing with some really stubborn HE's, in which case you should consider a booster. Anyway there is nothing wrong with using a metal
det cap (I prefer a .223 shell that has had it's top rim cut off), but if you are afraid of flying pieces of metal plastic pen tubes work nicely.
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SB15
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Exactly.
As for metal caps, I know a person who has a piece of a commercial No.6 cap lodged in their palm, and given the typically higher sensitivity of the
compositions we work with, that's enough to keep me away.
[Edited on 2-8-2011 by SB15]
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mabuse_
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| Quote: |
I don't understand the fascination people have with metal caps. With a decent primary, there is no need for anything more than a thin plastic tube; a
.22 casing or crimped metal tube only creates additional shrapnel danger. A compound cap is a simple device. Cut a plastic straw to length and seal
one end with hot glue. Press in your base charge with a wooden dowel. Press the primary directly on top using the same dowel. Insert a fuse/e-match
and seal the remaining end with hot glue. Done. |
Metallic caps are much more dangerous to produce, but on the other hand much safer once finished.
Imagine you bend a straw-type blasting cap by mistake? And what about ESD?
Does anyone have any data on Ag2C2.AgNO3s sensitivity to ESD?
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prometheus1970
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What is ESD? any relation to LSD?
Just because you're paranoid doesn't mean everybody isn't out to get you.
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prometheus1970
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I'm also very hesitant to use hot glue on a primary as heat sensitive as Ag2C2. I realize that the dangerous temp range for this primary is probably
well above the temp of hot glue, but a margin of safety certainly won't hurt anything. As for the shrapnel issue, a .22 shell only weighs .6 grams,
most likely not enough brass (|in flat pieces) to dangerously travel the 200 feet or so where I'll be standing.
Just because you're paranoid doesn't mean everybody isn't out to get you.
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prometheus1970
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I tested the .22 case with Ag2C2.AgNO3, it blew completely apart; it will definitely impart most of its energy from within that casing. I also made
another cap of simpler design. A piece of dinking straw(with epoxied fuse) with 100 mg acetylide pressed against the fuse tip, then with 1.2 grams
ETN pressed onto that, then held inside the straw with just enough Elmer's to keep stuff from falling out, but not enough that it wouldn't
harden(thick gobs of pva glue tend not to harden all the way through).
[Edited on 2-8-2011 by prometheus1970]
Just because you're paranoid doesn't mean everybody isn't out to get you.
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quicksilver
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Due to the posting limit of 2Mb because I would tack up some advertising that could just as easily be deleted later to show how things have changed
over the years in energetic chemistry and physics elements re: design (& implementation) of initiators. But that would be lame illustrative
advertisements which the science within could be summarized. If anyone really DOES want to see all sorts of commercial items in PDF format, PM me and
I'll dig them up and pin them or send them to some site. Detonators are today termed initiators, as they preform more functions as time goes on.
explosive bolts became extremely important not only to the aircraft industry but to NASA. To control time, direction, & amount of work via
energetic materials became more complex as different materials arose to meet the issues involved in (not only) mining and urban reconstruction but
geology & will eventually be a standard for geological exploration not only in deep sea environments but space as well.
How are we going to mine on the Moon except to make DuPont wealthier???? (Sorry- I could help that)
First of all, the shape of initiators have changed from the 6mm standard. {It used to be that NATO forces and commercial issues had a 6mm ID while
Warsaw pact countries had a 6mm OD.} The standard was a tube (cylinder) for a few reasons; the more important ones were ease of use & mfg. Costs
have risen so high, it's unbelievable due to tracking & serial numbers, one for each detonator one for who, where, and what mfg that unit, etc.
That's a LOT of numbers! The unit also may be used in seismic & geological applications as well as doing work as per mining.
Of course the science behind that has also changed. The shelf life needed to be increased (fulminate caps actually rarely lasted more than a year.
generally in hot climates they did well to last 6 months. The units now must also be waterproof and (usually) have more that one method of employment
(Nonel & electric, etc) but most important still is their primary job which is to transmit shock from one point to the next. The body must be of a
material that "shatters" rather than "balloons" so a unique type of aluminum is used that is also anodized and then coated with a polymer. The seal is
solid obviously and the only other opening is the initiation point. Many are now enclosed in a small box-like plastic housing*, others are no longer a
6mm cylinder tube. (General source: Explosives Engineering magazine) What once cost $2.50 a box of 100 fuse caps are now (occasionally) $39 a carton
of six units! Typical "fuse caps" are for the most part no longer mfg in the USA & in fact I know of only one mfg in Asia that still makes the
standard 6mm X 66mm #8 (I don't remember how long the #6 was but it was about 6cm or a little less). Caps were made longer than the level of the
ingredients for safety. They had to have some "crimp room" at the top and their seal had to be a very special highly flammable nitrocellulose,
waterproof material that sealed the cap but allowed the fuse spit to easily contact the seal with crimp a good distance from the component element(s).
EBW detonators are generally made by the same company that mfg the "blast box" (or visa versa) & are extremely expensive. Now coded signals are
employed with signal strength & encoding units so that wires are really no longer needed on distance or safety sites.
But the basics have remained. That initiator has to be of a strength that essentially insures that the product will preform. That means that the
concept of "over-driven" units have become the norm. The "compound" style of det design has also become the standard as the less primary used; the
safer that unit can be. It takes so little azide to initiate a compressed gram of RDX or PETN that it (the azide) does not even need o be exposed to
the same compression levels. Research has shown that the more "brittle" the container, the better the shock transmission. So aluminum that shattered
was also the norm of construction. This was usually the 5000 series of aircraft grade alloy that had great strength but when it did give; it shattered
instead of ballooning outward (for nano-seconds) & pushing the detonator away from the secondary material.
* This accomplished several things: it made more room for numerical codes, it made them more difficult to loose, it made them easier to apply to
flexible type cartridge products within a borehole.
Quite frankly I don't suggest anyone attempt to "make a detonator" unless what I had just written appears very old news. IF you are of university age
and want to understand (and use) energetic materials, you can do so via various programs available to university student in a legal, supervised and
education environment. Below is a sample of the programs available to those who have a true interest.
[Edited on 8-2-2011 by quicksilver]
Attachment: 2009ExplosivesCamp_01-copy.pdf (724kB)
This file has been downloaded 984 times
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-=HeX=-
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quicksilver: such courses probably are for the US... So for us Euro's I strongly suggest PAPER casings. Yep, paper tubes, one end crimped off, formed
around a pencil. Dip in Sodium Silicate to add some strength (or epoxy... or NC laquer!), fill with pressed RDX/MHN/PETN/ETN, then your primary, a bit
of pyrogen and an ematch. Seal closed by folding the paper and gluing, prior to dipping the resultant device in a lacquer or something to water proof.
Such caps (Assuming 1gr base charge) are good for most applications...
If you give a man a match he will be warm for a moment. Set him alight and he will be warm for the rest of his life.
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quicksilver
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I'm fairly sure that in most applications that would be satisfactory. It's too bad that information has become so restrictive that legislation still
focuses on "objects" & not behavior. ~-=(soap box warning)=-~
There may come a time when such a discussion is censored. In the UK recently a newspaper caught a lot of attention because they supposedly released
too much "explosive-making information" in an article on "7/7".
~-=(soap box: off)=-~
We DO have some excellent schools of mining, explos. engineering, & urban reconstruction here. Mostly in the public (State) University system.
Before the extensive NASA cut-backs there was a great deal of discussion of mining on the Moon within the next 30years.
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prometheus1970
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So, are you saying that unless this is already old hat to you, you should get professional training first, bypassing all amateur experimentation?
Just because you're paranoid doesn't mean everybody isn't out to get you.
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quicksilver
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Basically I believe in this hobby, that a person should study.....so that MANY of the common questions are no longer "common questions". Because that
would mean that the individual has studied deeply enough so that aspects of safety, elementary synthesis, construction, & design ramifications
have been covered in his learning to the point where the standard of discussions move into an area of actual "uncharted territory". I have good reason
for saying this......
Let's say you could look back on all the dialog in this Forum since it's inception; you'd see the same issues raised again over time. And one of the
most unique things are that they cover (perhaps) two books, Davis, & Naoum!
I would seriously bet a nice dinner that IF someone studied those two books to the point of KNOWING them as per an upper-level undergrad course; they
would rarely have a question that repeated itself within any area of the forum. The level of creativity would soar and the safety practices would get
refined & natural.
It's one thing to depend on a discussion for creative ideas, refining & entertaining certain practices, or think deeper into a certain standard of
workmanship (synthesis). However the nature of what is discussed is the same as high energy weaponry or lab-level practices (lasers, plasma, etc). the
basics should be a sound responsibility of the individual so that HE KNOWS THAT WHAT HE HAS LEARNED IS RELIABLE & AS SAFE AS IT COULD EVER BE.
The classic difference between amateur and professional is pay. What I am saying specifically is that there should (in a perfect world) not be a
definition of amateur as meaning "lower-grade". The ability to know a great many of the questions asked are out there with NO mis-interpretation as to
exacting science. People should defiantly experiment - no question (IMO). However they should begin their experiment with book in hand, rather than
anyone's opinion from the internet or what have you.
The last thing I would ever want is any harm to come to a member of this Forum, & in saying so I would rather they never take my word for
something that could be verified independently. Not because I would purposely write something incorrectly, but I'm just a human being & I make
mistakes.
So, am I saying to respond to people with UTFSE? NO, not at all. But IF that person does their own studying from reliable sources, they can be
reasonably assured of being safer, using the correct tools for the job, & certainly having building blocks for much more enjoyment of this
subject!
What's more the level of creativity will rise to the level of common ground within a framework of a standard of understanding that has often been
missing when the basics really need to be covered so that person understands WHY something will happen and what will happen rather than follow a
recipe & essentially miss a great deal of learning that could be the door to a serious level of creativity.
Finally.....we need to face reality. We may not HAVE this information after several laws gain a foothold. I'm quite serious about that. To miss an
opportunity to buy up several books that may become scarce or even unprintable would be a tragedy. In the UK there already is a standing degree of
censorship. in the USA we were extremely close with the "Feinstein Bill" (Goggle: "Feinstein Bill, bomb making literature") to having a door slam shut
on energetic materials literature or even open discussion. Gentlemen, that Bill is now law. How long are you going to wait to develop, retain, &
study - materials that may be as rare as the subject itself?
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grndpndr
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Not trying to be a smart ass but A good bit of whats been discussed and far more has already been talked about at lenghth from basic/more advanced
reinforced caps,to energetics--primarys-secondary composite caps etc etc.
All you need do is search the site for detonator design-blasting caps and your sure to find far more than expected.Siteds that are relavent dating
back to '05' at least.Its a real good Idea to check first to see if the topic isnt simply a repeat.But of course if you feel youve got something
new..Please share.
+1 in agreement w/QS.If you must experiment try to do so within the law, and safely.
I am retracted/apologizing for the post that continued if legality, safety was of great Import joining the military as a demolitions engineer would
be exciting for the adrenilin junkie.
But I realized many here are of age(18+) and at this point my patriotism for this adventure(middle east) is waning rapidly.Not to mention I suspect
many contributors are old enough to have son's of military age like myself. My apologys
[Edited on 9-2-2011 by grndpndr]
[Edited on 9-2-2011 by grndpndr]
[Edited on 9-2-2011 by grndpndr]
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grndpndr
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I would like to have access to a synthetic casing maybe similar to what was used for HG fulminate back in the day.My belief it was bakelite.Very
strong but brittle in thin pieces and light which should minimize fear of shrapnel.What I worry aboiut would be a det while in my hand not the small
fragments of likely grain wieght Al.Likely leathger gloves of a decent thickness would stop said 'shrapnel' and eyeglasses at least or preferrably
face shields.Lately if I were forced to work with detonators and primarys I would want some sort of hvy leather welding gloves along with the leather
welding jacket ,witha full face shield plus my glasses.And Ideally a tool that allowed me to hold the cap at a distance from my hands while working on
it.Even better a piece of plexiglass/polycarbonate bolted between vise/press det and me.
I think the nice thing about a stiff detonator container is it makes any pressing of the energetics safer by not allowing the flexible straw to move
about during the operation.I dont see how the straw keeps from bursting?Unless of course the primary-secondary dont need compression,and just minimal
confinement.
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prometheus1970
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Maybe they'll turn out less than optimally effective, but I just use a few pounds of force when I press acetylide/etn in a cap, not enough to strain
the casing, just nough to squueze most of the air pockets out of the material and make it as contiguous as possible. We'll se how these turn out...
Just because you're paranoid doesn't mean everybody isn't out to get you.
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grndpndr
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I gotta say Im no chemist but on my worst day I wouldnt consider simply guessing as to the amount or density of the materials pressed into a
detonator.Arent you at all interested in repeatable results and optimal use of expensive chemicals not to mention the time spent? (apparently not so
much time spent with attention to detail)
Ive got a real bad feeling if your not bothering to wiegh or press your energetics to a known value for a blasting cap for chrissakes.What else are
you just half assing along with?
That attitude will get you hurt.Sooner rather than later Id wager.
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quicksilver
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Ensign Bickford (the fuse mfg) experimented in the 1950's with a PBE (plastic bonded explos.) cap. It was actually ALL explosive. It was less than an
inch wide a cylinder of hard explosive plastic that screwed on to the end of a fuse with "barbed" threads (in a 6mm hole in one end of the cylinder)
that would keep it in place. It's concept was for touching off dynamite that was fixed into a hard borehole but did not detonate. It would be totally
water resistant and when in place could withstand direct water contact. It could also be designed with a molded pair of leads for an internal
bridge-wire, making it able to be used with almost any manner of initiation. The actual formula is no longer under patent and is available to those
who have a fair background in polymer chemistry. It's not a lightweight thing to mfg.
The idea eventually was bought and now Sandia Corp is doing research in a similar area: that the cap as a whole is the detonator - in & of itself.
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pjig
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@Quicksilver
This almost sounds like a form of nipolite...(Not sure if I spelled that one right). The old german type of grenades, that where A ddsp/pent or other
energetic bound and hardened into the shape of a grenade. The material was hard enough that it could be threaded, and the det and fuse lever threaded
into it. ( No need for a casing) ..
Is what your speaking of, a booster of types?
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prometheus1970
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I have to admit that, while I find merit in/admire the scientific approach to this endeavor, my motivation is more pragmatic at this point. I'm still
trying to get a firm grasp of the basics of energetics. I'm nowhere near the point of 'boldly going where no man has gone before' and expanding the
knowledge base of this area of study. Right now I'm just trying to stay safe, out of trouble (with the law/wife), etc. once I have a good, solid
grasp of what I'm doing, I'll apply what I've learned from books and experience toward coming up with something more innovative.
[Edited on 2-10-2011 by prometheus1970]
Just because you're paranoid doesn't mean everybody isn't out to get you.
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quicksilver
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I would have to dig becasue there are about half a dozen energetic polymers. but I wouldn't be surprised if the Germans worked with them (1940's).
Polymer chemistry demands the correct starting blocks & is rather ridged in it's format. I have a book on synthetic rubber that covers a great
deal of that issue; including all sorts of explosives; it's not a lightweight subject.
@prometheus1970 :
I'll share with you an interesting antidote; I have another hobby that I have MUCH less knowledge of: Extreme High Voltage applications.
High energy just trips my trigger. But the Forum I belong to is very strict. They don't allow anyone to ask for a schematic per se' (like a recipe'),
there are some very serious safety rules (as you could imagine) but they actually don't just post them. Their feeling is something like "do your own
work at the basic level or suffer the consequences". - Which I personally don't believe in, by the way*......(They have a great many rules....)
In that respect (electronic engineering), I am very much a "babe in the woods". Some of these folks (quite a few) have PhD's. But demanding that I
grasp some of the formula has been very valuable BECAUSE it helped me put stuff together that was a major thrill. Demanding of myself the discipline
to learn aspects of trig was not easy (there is a lot of complex arithmetic and trig in electronics formulas) and I still have a VERY long way to go
so that I could get to the "creativity point" that you mentioned. But I do see it. I do see how by understanding certain aspects of the core science,
it will make things more fun down the road. Frankly some of those issues are a real pain in the ass. The safety issue was very significant as well; I
needed to understand what aspects of safety were of direct influence with a high (electric) energy lab. And they are somewhat unique.
I DO know where you're coming from, & I respect it. I believe however that "sharpening your own sword" makes for a keener edge. I's been very
difficult for me to immerse myself in another hobby where I essentially have to start all over but it's been a very good experience. I remember asking
how to determine the output current from a given capacitor and was simply given a formula. I hated that type of teaching. I like things explained. But
it did help in that I HAD to find appropriate background as a starting place for the equation, etc.
I doubt that I would even be able to conceive of something barely new in electronics: I can't even picture such a thing. Thus far I've made a few
Tesla Coils, Can Crushers, and application specific voltage multipliers; no big deal....but it's been fun.
Believe me when I say I understand where you're coming from.
* Warning another person from a really terrible mistake should never be dismissed as a Darwin Award phenomenon.
[Edited on 10-2-2011 by quicksilver]
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hissingnoise
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| Quote: | | . . . once I have a good, solid grasp of what I'm doing, I'll apply what I've learned from books and experience toward coming up with something more
innovative. |
I think the scope for innovation in cap-design is limited, to put it mildly!
And it's difficult to see how the current detonators could be improved . . .
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