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Author: Subject: A more durable improvised detonating cord?
franklyn
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[*] posted on 29-7-2010 at 09:01


This video shows the rope braided in slow motion
fast forward to a third of the way into the video
and view the middle third of it.
http://www.youtube.com/watch?v=UyDHBNix6hA

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[*] posted on 29-7-2010 at 09:26


The astounding level of intricacy in both the machinery and the production itself is appropriate since in many instances the rope displayed will be relied upon to save / protect human life.
But in a sense couldn't that also be said about fuse or explosives? I would love to see a video of that quality on the production of det-cord, blasting fuse (the real thing) or related industry-standard production techniques. ISEE's web site once had that from the Institute of the Makers of Explosives. But it's been replaced for some time now.
If you search ARCHIVE.ORG you can still find a film I saw as a grammar-school kid with a title called "Blasting Cap Danger!" We used to have to watch several films of that classic genre'. It's a serious safety issue but it may make some people laugh themselves silly.
http://www.archive.org/search.php?query=explosives%20AND%20m...




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[*] posted on 1-8-2010 at 09:18


Quote: Originally posted by franklyn  
Useful toys
Bond Magicord Machine ( knitting type )
http://www.bond-america.com/help/help_cc.html
http://www.allbrands.com/products/abp08057-0300.html
http://www.allbrands.com/products/abp04018-0300.html
http://www.allbrands.com/products/abp08059-0300.html


Here's a video of such a toy.

http://www.youtube.com/watch?v=6Ya0UdAm7Io&feature=relat...

Forward to where you can see the sleeve being formed. You could lower a funnel filled with your HE right in the middle of the sleeve.

Now the only problem I see here is that the HE is not compacted at all. But if you ran this sleeve through the fuse machine I posted a link to earlier, that would compact it somewhat. Or maybe tie the sleeve to a post at one end and then pull on the other end.. the stretching will compact it a little, keep the sleeve under tension (hang it over something and tie a weight to the sleeve or something like that) and wrap the sleeve with tape as tight as you can. Or compress the sleeve between your fingers and guesstimate the diameter.. get a piece of tubing with a smaller inner diameter than what you measured and see if you can pull the sleeve through the tubing.
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[*] posted on 2-8-2010 at 05:23


The toy is a good one and the fact that it drops from the bottom, even better. Realistically though, after examining the real thing, I don't know if there is a way to pack powdered material within woven structures alone after certain diameters have been reached. The real thing uses a "core tube" & BP blasting fuse as well as time fuse uses a "core tube". The advantage there is not only one of production but of variation in energetic material weight per meter. You would have much finer control over alterations of weight / volume with the "core tube" concept. The woven hull is very valuable to prevent kinks, protect the tube (which would be thin walled) from abrasion, & aid identification. In times past, the use of tar or similar adhesive would further reduce kinks. But I am convinced that the right selection of tubing material and level of compression will help a great deal. It seems to be a two tiered system.



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franklyn
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[*] posted on 13-8-2010 at 12:31


Det Cord in action
Slow motion view as two lines detonate from the lower left into the shack.
http://www.youtube.com/watch?v=zNP2xCfOdjI
Slow motion view as the line detonates from the lower left on to the bus.
http://www.youtube.com/watch?v=kYjzIMLQYVs

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Microtek
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[*] posted on 13-8-2010 at 13:20


I think those two clips actually show shock tube instead of det cord. But then, I would much rather have a good way of making shock tube than det cord....
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[*] posted on 13-8-2010 at 15:17


@ Microtek

Yes I'm sure you"re right , my fault for not distinguishing the two and using
the term indistinctly. Detcord and Shock tube refer to different materials.
http://www.shocktubesystems.com/drontey.htm
The clue in the video is there is no evident blast effect such as dust in the
immediate vicinity of the traveling wave as you would expect from detcord
which is quite violent. Shock tube can be initiated with a handset as seen here _
http://www.youtube.com/watch?v=1AuTxeV0lxU
http://www.youtube.com/watch?v=C0nEaYL1kps
Shock Tube
http://www.iie-online.com/download/fs/doc/safety_pdfs/shock-...
Detonation Cord
http://www.dynonobel.com/NR/rdonlyres/209B7E9F-6C15-40EF-B67...
Det cord demo from a safe distance.
http://www.youtube.com/watch?v=kdycQR0BnmM

P.S.
In case some missed it in my earlier post in this thread
there is a third method being developed

Light speed detonation velocity
Optic Fiber Laser Detonator
http://www.osti.gov/bridge/servlets/purl/219536-Awf457/webvi...

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[*] posted on 7-9-2010 at 09:39


Here is something (Microteks idea originally... That man gives me all my best ideas to be honest!)

You know you can buy, from various magic suppliers, a product called 'Flash String'. Well one US suppler sells 'Flash Cord' that is like a thicker flash string made from several 'Strings' braided together. The one I got, 30 feet, was about 6mm diametre.

MHN and NG form a collidon of sorts, as does NG and NC.

I first tried a ten foot length.

Acetone dissolves them all. MHN is mixed with NG (I did not make any measurements, it was more of a timewasting experiment in boredom) and acetone is added. The cord is soaked in this and the acetone allowed to evaporate by heating at 50* celcuis, leaving the cord impregnated uniformly in explosive, and moreso a collidon than a cord. Its physical characteristics were somewhat altered, and it also propagated detonation.

Next, another ten foot length of cord was cut, and a thread tied to one end. The thread was pulled through ten feet of shrink tubing which had an ID of 8mm. It was 'low temp shrinking' stuff.

The cord was treated, and the acetone mostly evaporated normally prior to drawing it into the shrink tube sleeve where it was heated again for several hours at about 50*. use of a hairdryer shrank the tube, sealing it up. Some composition now came out the end, as an 'extruded' plastic. Interesting, I thought.
The cords ends were simply taped shut. Taping a cap to the side, I found again that it propagated detonation.

I know that NC NG MHN mixes sometimes fail so perhaps addition of a nitramine (RDX) would help a bit, I think it would.

What do you think about this idea? Hardly optimum but I think it makes a nice consistent product.

BTW, Microtek, I recall your idea involving tubing, butane and oxygen in stiochemetric ratios as a shock tube. Anything ever happen with that idea?




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[*] posted on 7-9-2010 at 09:52


Quote: Originally posted by -=HeX=-  

BTW, Microtek, I recall your idea involving tubing, butane and oxygen in stiochemetric ratios as a shock tube. Anything ever happen with that idea?




Acetylene perhaps?!

A Plumber! A PLUMBER!! My kingdom for a Plumber!!!

"In a time estimated to be about 6 sec, an accidental fire-initiated decomposition
flame in acetylene at ca 200 kPa in an extensive piping system traveled
successively through 1830 m of 76-203-m pipe, 8850 m of 203-mm pipe, and
760-m of 152-mm pipe." [37,180 feet of pipe.]

K&O 3rd


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Microtek
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[*] posted on 7-9-2010 at 13:18


Well the idea with a gas filled tube was something I saw in a patent. I tried it out with hydrogen and acetylene as well as the propane/butane mix which is commonly used in camping stoves and lighters. I experimented with fuel/air mixtures within the explosive limits, but found that in small diameter tubing (2-3 mm IIRC) you are likely to get a very sedate propagation, at least when simple ignition is employed.
So, I would think that to come up with a system that actually works as a shock tube substitute you should:

- Use pure oxygen rather than air
- Use larger diameter tubing
- Initiate with a small cap rather than simple flame

Personally, I would prefer not having to increase the size of the tube.

Edit: Of the three systems, hydrogen worked best by far under the given conditions.

[Edited on 7-9-2010 by Microtek]
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[*] posted on 7-9-2010 at 18:27


Hydrogen and Chlorine is photoactive and explosively reacts upon exposure to light in a 1 to 1 molar ratio
to form HCl. Opaque tubing filled with this mixture would achieve wave propagation at some fraction of the
speed of light since the light emitted by the reaction triggers the unreacted portion ahead in the tubing.
The admitted gas mixture follows 3 or 4 ball bearings introduced inside the tubing snugly fitted at one end
but not tightly , so they move through by just jerking the tube , and are pulled along by applied vacuum at
the other end. This assures complete purging , so the charged gas mixture remains unadulterated.

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Microtek
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[*] posted on 8-9-2010 at 00:26


Nice idea, Franklyn. The question is whether the emitted light is of sufficiently short wavelength to propagate the decomposition at a higher than usual rate.
I remember seeing a demonstration where a photo flash was used. It involved three vials of H2/Cl2 behind three screens of glass. One screen was clear, one was blue and one was red. When the flash was fired through the clear or blue screens, the gas mix would pop, while the red one would block the short wave lengths so no ignition took place.

Or course, it might be possible to use the gas mix as a sort of primer mixture in an ampule preceeding the blasting cap, with a fiberoptic cable in place of the actual shock tube.
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[*] posted on 8-9-2010 at 05:01


@ Microtek

There's nothing to say that the H2 / Cl2 mixture cannot also additionally be
seeded with something having a different emission spectra , argon perhaps.
Regarding your application of acetylene :
Enthalpy of elemental Oxygen is zero. Substituting a more energetic oxidizer
such as ( N2O ) Nitrous Oxide should markedly improve wave propagation.
On page 185 of International Critical Tables regarding Explosive mixtures is
described a mixture of 1 to 2 molar ratio Acetylene to Nitrous Oxide , noted
as having ~ 2580 m/s velocity of detonation.

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[*] posted on 8-9-2010 at 10:20


Quote: Originally posted by -=HeX=-  

BTW, Microtek, I recall your idea involving tubing, butane and oxygen in stiochemetric ratios as a shock tube. Anything ever happen with that idea?


No doubt the collective will —

A. Be astounded to know that there is a book on gaseous detonations
B. Be amazed to know that I own a copy.

That said la book is tres theoretical.

MA Nettleton
Gaseous Detonations Their Nature, Effects and Control
Chapman and Hall
1987

'bout the only useful easily found info dobe —

(2H2 + O2) + 5He Calc. 3613 m/sec Exp. 3160
4H2 + O2 Observed 3344 Theoretical 3425

Vapours
100% HN3 2.60 km s
100% ClN3 2.3
100% C2H2 1.92
90% H2O2 + 10% O2 1.92

NB - Velocity does not guarantee ignition.


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[Edited on 8-9-2010 by The WiZard is In]
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[*] posted on 4-2-2011 at 05:02


Maybe a bit of a bump in this topic but I had this idea for a while.
Get a silicone tube and fill it with plx.
Critical diameter can get low as 4.7mm with 2.5 wt% of ethylenediamine.

What are your ideas about this?
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[*] posted on 4-2-2011 at 06:23


One of the nice things about commercial det cord is you just cut what you need and go- liquid or gas filled tubes can propagate a detonation, but I don't see them as practical for field work. Solid is the way.

The original "cordeau" was made by filling a short heavy walled Lead tube with cast TNT (or a tin tube filled with picric acid) and then drawing it through a series of dies in the same way wire is drawn- Producing a long thin moderately flexible tube filled with crushed HE. Perhaps another look at this technique?

[Edited on 4-2-2011 by Bert]




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[*] posted on 4-2-2011 at 09:17


@ Bert:

The "draw" concept could work no doubt. but with TNT. I have seen wire drawing machinery before and the Pressure is substantial. TNT appears safe from friction/impact enough to attempt a small section. but the COST (of the device) is substantial. There is a tubing reduction machine that can be hand cranked (if one could be located) it's used in some jewelry applications and there may even be a way to work with this on a manual basis. But where to get lead tubing?

ANY tubing has criteria that is challenging. It must be thick and tough enough to bend without tearing of permanently kinking, yet thin & flexible enough to receive initiation from adjacent shock (cap blast).

[Edited on 4-2-2011 by quicksilver]




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[*] posted on 4-2-2011 at 10:20


But besides the field practical side of it. If you just consider you want a certain length of detcord then you can make it.
The liquid plx has a constant and uniform density therefore no problems with loading and very quick to manufacture.

I tested a 9mm ID tube, but it didn't detonate (blasting cap inserted in the liquid)
While from the same batch of plx a vial of 25ml did detonate (1 minute later) with an exact same blasting cap... how could you explain that?

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[*] posted on 4-2-2011 at 15:39


Jeez, what about a liquid energetic soaked into a thick string which is pulled through the tube?

I make MEKP caps with straws and cotton wool...

Put a thread through a tube with compressed air, soak a thick cotton yarn in EGDN, methyl nitrate, or maybe NG, then use the thread to pull the yarn into the tube while the end is submersed in the explosive as so not to introduce air. Seal the ends when done...

Heck, dissolve some more powerful explosive into a liquid explosive to make a syrup. Even better! Is ETN soluble in EGDN?




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[*] posted on 5-2-2011 at 06:25


This could be an ignorant idea, but for people in the US (or other countries with lax gun regulation), couldn't one use double based powder as absorbent for the ETN or explosive of choice?



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[*] posted on 5-2-2011 at 07:34


Smokeless powder grains are rather large for a small diameter tubing although DBSP/ETN and combinations would be relatively inexpensive.As far as Lax gun regulation thats a matter of opinion and a political statement not altogether popular
in the USA.
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[*] posted on 5-2-2011 at 08:00


How to do it the easy way....

We suspend the very thin nylon tube from 50f-100ft with a weight on the bottom, so this way it is straight. Then, we start filling in all that hotness from the top by simply using an appropriate diameter metal rod (but that can slide more or less freely through the tube....so pretty thin rods that I saw at Home Depot) and just have it tied by a thin fishing line/weaving thread. So we just let it slide down all the way to the bottom, bringing with it all the ETN, then pull back up and repeat until the thing is full.



And you ask me if that's impractical and you don't have 50ft.......no doubt but it is easy, cause I have a staircase that's over 80 feet high or so...... If that's not enough, I suspend that hotness from somewhere higher. But if you want practical, than I suggest getting some type of pressure machine, having some kind of light fit plug with a lead line. So you put in the pressure, pushing the plug, which pushes ETN. Once done, pull the plug back out by a thread.

I should so flaming patent that! ;) But det cord makes too much noise, so not my specialty.


P.S. Wizard, WTF? seriously.....replying with essays is ridiculous. Sentences of 100 words or less work too. :(

[Edited on 5-2-2011 by holmes1880]
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[*] posted on 5-2-2011 at 08:20


Would plx soacked in cotton also work, like NG?
And when using pure liquid PLX it didn't detonate with a blasting cap.
While it did while it was in a vial where there was more plx right around the blasting cap...
Still can't figure out why that didn't work...
9mm ID tube, 7mm blasting cap OD, glued inside the tube full of plx...
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[*] posted on 5-2-2011 at 09:45


Quote:

Smokeless powder grains are rather large for a small diameter tubing although DBSP/ETN and combinations would be relatively inexpensive.As far as Lax gun regulation thats a matter of opinion and a political statement not altogether popular in the USA.


I wasn't implying to use the grains as is, rather dissolving them with the explosive of choice, in the hope that this would form a paste. The added bonus is that the stabilizers in the powder reduce the hazards associated with NC.

As for lax gun regulation, I fail to see how that statement is political. You are trying to make it political. In my book it simply means easy access to guns without regulatory hassle. I fail to see how that is a political statement, as there is no judgement or ideology associated with it.




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[*] posted on 5-2-2011 at 09:58


The tubing is actually the most critical component. I have already thought of how to fill it with no problem in lengths of up to 10 meters (perhaps more) but the material is not something that can be some ridiculous item like vinyl tubing or such. It must be thin, strong, yet able to transfer shock energy very easily.

A "fuse-weave" machine could be used obviously but the cost and the final sealant would be a serious mess and lack professionalism. A fuse-type weave machine is also unpredictable in-so-far as it's total length as the spools are not that predictable until it's been used for some time.

It's actually a problem in mechanics. A simple experiment will prove what I mean. Use a 10meter section of .25" clear vinyl tubing so that you can watch the interior. To that afix a funnel so that it's quite tight and re-enforce it with a clamp. Use common table salt and go to any area with an over-hang or roof and start to "twirl" the tubing by holding the funnel so that it makes gentle figure "8"'s. as it continues it's movement gently pour in salt and the tube will fill with remarkable compactness. HOWEVER vinyl will never transmit effective energetic shock and you are really only left with 25-30 feet at best. It's a very ghetto method but the filling- per se' is NOT the problem......the tubing and it's characteristics ARE!

You could also do this with forced air and make it actually continuous but the most I have experimented with was several feet and the method worked well. Again....it's not the method to get it within the tube but the choice of tube itself that is a challenge. If you ever really want to experiment with the mechanics of this cheap table salt is a fair go as it does have similar consistency albeit a bit tougher, than many energetics. For Heaven sake NEVER consider peroxides as a kink will be a disaster....

This whole subject had been a "how-to toy idea" for many, many years. I really believe that the best method is to eventually buy a fuse making machine. If anyone has any experience with leather or braiding they know there is several types of braiding that would work manually but it's simply to much bother by hand and with anything but proper tightly woven cotton or a blend. A device similar to a KUMI Loom may be workable (Kumihimo braiding).




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