Sciencemadness Discussion Board - Bickford fuse style home made detonating cord experiment

Bickford fuse style home made detonating cord experiment

markx - 9-9-2014 at 23:49

As the evenings grow longer and darker by the day, I decided to fight the boredom with designing and testing a "shock tube" type of impulse transfer media. That's what happened:

The tubes designed had an active core diameter of 2mm and the fillings used were PETN and RDX. The cords were phlegmatised with a solution of natural rubber in alkene mixture to desensitize and fortify the construction (dipped in rubber glue to keep things from unraveling, that is). The filling rate was 3,3g/m and the density of the filling would work out as approximately 1g/cm3. Initiation was commenced by 0,3g of ETN at a density of 1,5g/cm3.

As I predicted so cunningly, the media with RDX did not dissapoint my expectations and resisted all attmpts to initiate it with utter fortitude.

And again, the media with PETN also followed my hopes by imprinting its outer structure in great detail into the aluminium profile that it was taped onto.

[Edited on 24-9-2014 by Bert]

APO - 10-9-2014 at 01:07

Have you tested from the batch of RDX that you used?

markx - 10-9-2014 at 01:20

Quote: Originally posted by APO

Have you tested from the batch of RDX that you used?

Yes, of course, pretty standard quality from Bachmann route with 197C melting point and 65cm drop test height with 2kg weight. It does just fine in diameters >2mm, but I guess in the shock tube application the dimensions were too close to critical. Also the phlegmatisation will hinder initiation ability...perhaps an uncoated cord with same filling will fire successfully, but I have not tested that yet.

Bert - 10-9-2014 at 10:57

In my experience, "shock tube" is a hollow tube with a very small amount of HMX/Aluminum powder dusted onto the walls... It doesn't even rupture the plastic 3mm spaghetti tube.

Common brand name: Nonel

The stuff you're making is usually called detonating cord, cordeau, Primacord or such. The core Dia. you show looks similar to commercial "signal line" det cord.

I would very much like to see your fuse spinning machinery, and know what the jacketing materials are, what pitch and layering scenario, any plans to incorporate waterproofing layers into the spinning & such- Also, do you have any way to test velocity of detonation? Got access to an oscilloscope or a know standard explosive such as commercial det cord to use the Dautriche method

[Edited on 10-9-2014 by Bert]

markx - 10-9-2014 at 12:42

Quote: Originally posted by Bert

In my experience, "shock tube" is a hollow tube with a very small amount of HMX/Aluminum powder dusted onto the walls... It doesn't even rupture the plastic 3mm spaghetti tube.

Common brand name: Nonel

The stuff you're making is usually called detonating cord, cordeau, Primacord or such. The core Dia. you show looks similar to commercial "signal line" det cord.

I would very much like to see your fuse spinning machinery, and know what the jacketing materials are, what pitch and layering scenario, any plans to incorporate waterproofing layers into the spinning & such- Also, do you have any way to test velocity of detonation? Got access to an oscilloscope or a know standard explosive such as commercial det cord to use the Dautriche method

I stand corrected....yes, by design it is closer to a detonating cord than a shock tube. Or a bloody fast burning visco for that matter.

The machine responsible for this fast fuse can be seen here:

https://www.youtube.com/watch?v=ZnMqOF28STM

As for materials...this particular length of cord used cotton thread in the inner layer and polyamide thread on the outer shell (it is cheaper and thinner and has a smooth surface to minimize the outer layer thickness). Waterproofing was made by dipping into diluted rubber glue. I also use this for waterproof visco...works very reliably and is quite convenient.

The machine is constructed with 3 independently PWM-d motors...so any pitch can be dialed in with the turn of a button. I have found that keeping the upper platform rpm to a minimum (only enough to run the "mixing rod" in the upper funnel and keep a consistant powder feed) and the lower platform rpm dialed in depending on the size and type of thread used, gives the best results. In fact one does not need two counter revolving platforms to spin double layered visco type of contraptions. One of the platforms can be stationary and still the machine works just the same. If one thinks about the relative nature of movement (speed) then this fact becomes strikingly apparent....but it hit me only after I had already completed the design.

About the detonation velocity...yeah, no luck in getting ahold of a reliable commercial standard. I guess I will have to build some sort of contraption to measure the speed. Might just be another interesting project

goldenoranges - 10-9-2014 at 13:01

That visco machine is interesting, you could make good money selling something like that on eBay, i for one would buy one

Bert - 10-9-2014 at 13:42

Quote: Originally posted by goldenoranges

That visco machine is interesting, you could make good money selling something like that on eBay, i for one would buy one

What is this "buy" you speak of?

goldenoranges - 10-9-2014 at 14:11

Awesome

Thanks!

markx - 10-9-2014 at 22:48

Visco spinning machines via DIY are a pretty old story by now. They are quite easy and cheap to build and make a very interesting and educational project. Not to mention the unlimited scope of fuse and cord formulations that become so easy to turn into reality.

On the note of cord testing...here is the test body for compressive stregth evaluation of mortar (30MPa dry concrete):

Rigged up with 80cm of PETN core cord...and the resulting damage. I do not have to mention how loud this test was....

Energetic Einstein - 15-9-2014 at 16:42

Not gonna lie. Even though its not shock cord that is still Awesome!!

packetforger - 17-9-2014 at 03:35

Any notion of what kind of lengths (as in, one continous, long, cord) you are able to manufacture using your current method of manufacture?

I only ask because I wish back in the day I had a reliable method of producing long lengths of consistent detcord... It would have been incredibly useful for all kinds of things! Methods experimented with at the time never really produced much more than a meter or so at a time, with incredibly inconsistent performance.

markx - 17-9-2014 at 04:21

Quote: Originally posted by packetforger

Any notion of what kind of lengths (as in, one continous, long, cord) you are able to manufacture using your current method of manufacture?

I only ask because I wish back in the day I had a reliable method of producing long lengths of consistent detcord... It would have been incredibly useful for all kinds of things! Methods experimented with at the time never really produced much more than a meter or so at a time, with incredibly inconsistent performance.

In principle the length is only limited by the capacity of collection spool.....currently about the maximum of 5m in one length can be spun with ease (I've tested the lengths with visco fuse, but there is no principal difference what substance or formulation gets wrapped into the threads) . And of course the operators capacity towards working with coupious amounts of energetic material. The latter one is my limitation. But as the cords can be joined together, I guess there is no real limit in length.

packetforger - 17-9-2014 at 04:41

markx: ah, excellent! Have you published schematics for your particular machine, for others to attempt to replicate such a build?
I can think of several uses for a machine that churns out lengths of fuse, especially for fireworks displays. Had never even considered repurposing one to manufacture detcord, so congratulations on your ingenuity!

Also, it probably is the critical diameter of the RDX that made it non-initiable or rather, incapable of propagating detonation, perhaps "sensitizing" it with a percentage of PETN or similar might assist in getting it "going".

Bert - 17-9-2014 at 06:07

Quote:

The tubes designed had an active core diameter of 2mm and the fillings used were PETN and RDX. The cords were phlegmatised with a solution of natural rubber in alkene mixture to desensitize and fortify the construction (dipped in rubber glue to keep things from unraveling, that is). The filling rate was 3,3g/m and the density of the filling would work out as approximately 1g/cm3. Initiation was commenced by 0,3g of ETN at a density of 1,5g/cm3. As I predicted so cunningly, the media with RDX did not dissapoint my expectations and resisted all attmpts to initiate it with utter fortitude.

If the RDX filler will function at the Dia. of fill used in the cord WITHOUT the inert rubber cement coating... And the issue is phlegmatization due to penetration of the core by the thinned out rubber cement- Perhaps a different coating method or material is in order?

Commercial det cord I have handled has a thin inner plastic liner, made by wrapping a "tape" of plastic in spiral fashion around the core of PETN, which is then wrapped in the spun/woven outer covering. This prevents loss of the filler during handling, and gives some degree of water resistance. If a dedicated cord machine were to be made, could this be implemented as an additional wrapping level above the thread wrapping stages?

If applying an outer coating via liquid plastic, consider the coating used by commercial visco manufacturers? It does NOT penetrate the black powder core of this type of fuse.

Firefox pyrotechnic/rocketry supply catalogue

Quote:

Nitrocellulose/Polyester Fuse Coating, NC/PE thick butyrate in various colors (see stock #'s for corresponding color), Ship ORM-D, Non-Hazmat Looking for a better safety fuse coating agent for use with our fuse machines, Firefox researched, experimented and came up with solutions to a couple of potential problems that standard Nitrocellulose lacquer has when coated on safety fuse. As most of us have experienced, NC lacquer can burn off ahead of the burning fuse powder core making it dangerously liabel. I have had premature device ignition caused by the flaming lacquer before the burning fuse core actually made contact with the primary composition, thus effectively eliminating the essential delay. Secondly, some NC lacquers become brittle in prolonged storage. This is most likely caused by insufficient or a complete lack of a stabilizer added to the lacquer. Aging brittle fuse will crack when bent allowing moisture in and ignition failure, especially when using in moist atmospheres or underwater. The answer is our field tested Nitrocellulose/Polyester Fuse Coating. We start with a high solids loadings NC lacquer, blend in a soluble polyester resin which improves flexability, aging and effectively reduces lacquer burnoff. Then a nitro group stabilizer is added to gaurd against decomposition and increase shelf life almost indefinately. This NC/PE lacquer is viscous and dries rapidly so it only has time to soak into the cotton fibers of the fuse and not the powder core. Can also be used to coat blackmatch, quickmatch, homemade Thermolite Ignitercord, as an electric match overcoat and similar useage.

markx - 17-9-2014 at 06:57

Quote: Originally posted by packetforger

markx: ah, excellent! Have you published schematics for your particular machine, for others to attempt to replicate such a build?
I can think of several uses for a machine that churns out lengths of fuse, especially for fireworks displays. Had never even considered repurposing one to manufacture detcord, so congratulations on your ingenuity!

Also, it probably is the critical diameter of the RDX that made it non-initiable or rather, incapable of propagating detonation, perhaps "sensitizing" it with a percentage of PETN or similar might assist in getting it "going".

Thanks for the kind words

I have no published plans for the machine, but there is nothing much to it. The only big difference compared to the rest of visco machine plans that I have studied is that I use 4 independent pwm-d 12V dc motors to drive every moving stage of the machine separately, hence allowing me to change the transmission rpm ratios with just the turn of a button. And I constructed a primitive traversing stage to "evenly" distribute the product onto the collection spool. All the other designs that I saw had one central motor that drove the whole machine at certain transmission ratios. The only way to change these ratios was to install different size drive wheels. Very inconvenient as the transmission ratios depend on core diameter, the number of threads used, the type and width of threads etc. To get these ratios right without fine tuning is pure coincidece and I knew that I would not be so lucky, hence the fully adjustable rpm controls.

The failure with cyclonite core is definately bound to critical diameter of that substance, or rather the composition of rubber impregnated cyclonite mix at that particular density. I will try the uncoated cord sometime in near future and that should give us an answer wether looking for a better coating material is justified or not. It would be great if the design could also work with a RDX core (it certainly does so with larger core diameter, say above 4mm)....I would feel much more comfortable with handling a more stable substance. But the PETN core is also very efficient, it's just staggering how much power is packed into this thin and innocent looking cord.
For coating of visco I have used sanitary silicone thinned out with toluene based solvent. It creates a thick slurry that does not readily adsorb into surfaces but rather coats them. It creates a solid silicone coat around the visco and turns it really waterproof. The downside is the long drying time...several days are needed for the diluted silicone to polymerize into a cured mass.

The incorporation of a tape layer into the woven structure is definately possible...in fact I think it might be as simple as rigging a tape spool and guidance support on one of the spinning platforms (preferably the lower one). In worst case scenario a separate platform for tape can be added.

markx - 18-9-2014 at 10:00

A nice fresh bundle for illustration:

NeonPulse - 18-9-2014 at 16:14

I have considered building one of these machines for a while now and this post has given me the extra drive to do so. Fuse is impossible to get where I live and would be much easier than having to carry cable to vaporize my experiments. Good fuse is important and with a machine that can be fed with HE makes the project that bit more interesting. I did find some plans out there and it is much more simple than I thought it would be.
Another example of great work Markx.

markx - 19-9-2014 at 00:20

Quote: Originally posted by NeonPulse

I have considered building one of these machines for a while now and this post has given me the extra drive to do so. Fuse is impossible to get where I live and would be much easier than having to carry cable to vaporize my experiments. Good fuse is important and with a machine that can be fed with HE makes the project that bit more interesting. I did find some plans out there and it is much more simple than I thought it would be.
Another example of great work Markx.

The construction is quite straight forward with these machines. There are some small tricks to get it running consistantly and properly. One being the easy ability to change the transmission ratios and second being the construction of the powderfeed nozzle. Against intuition a funnel geometry at the point where the threads wrap the powder into the core does not work very well. The powder tends to fall through the threads and gets pulled down on the outside of the bundle, creating a lot of waste and dust that will hit the lower spinning platform and get thrown all around the machine. With highly energetic materials this is a right up catastrophy. A flat geometry is so much better. Also a means to agitate the powderfeed is essential for consistant results. There are very few materials that flow well enough to provide a consistant feed rate without some agitation. I used a stationary rod with a loop at the end and a strip of scouring pad glued to it lenghtwise that the spinning funnel rubs against. This option works surprisingly well for most compositions. A guide thread or gentle vibration would also work I suppose, but this option was the easiest to build...no moving parts.
Surprisingly the most expensive part of the whole project is the thread

One can forget about buying thread on small sewing spools....the big insustrial spools are the only option. I rewind onto smaller dedicated spools and then feed the machine. At first I bought the threads on small spools to avoid rewinding and one filling cost me more than the whole machine.

markx - 19-9-2014 at 13:59

Some detonography on a piece of 2mm thick sheet metal with PETN core cord:

The power is immense as can be seen from the extensive deformation of the witness plate...

[Edited on 19-9-2014 by markx]

Energetic Einstein - 19-9-2014 at 14:35

That's incredible!
Do you only use RDX as your core, and what do you use in your blasting cap? Can you adjust your core load so you can have 10g per meter load?

markx - 19-9-2014 at 15:06

Quote: Originally posted by Energetic Einstein

That's incredible!
Do you only use RDX as your core, and what do you use in your blasting cap? Can you adjust your core load so you can have 10g per meter load?

The cord has a PETN core....cyclonite seems not to be working well with such small diameter charges. It does very well above 2mm diameters, but not so much around or below that. I still have not tested the raw (unglued) version with cyclonite core, but even if it works it will still be in need of a different glue and/or different weaving pattern/layers. For small thin charges nothing seems to beat PETN in propagation ability and power...well at least nothing in the well known accessible spectrum of energetics.
The load rate can be adjusted via different feed nozzles....and yes, 10g/m is not an obstruction if the need should arise. In my opinion such load rates are unduly high. Appropriate for breaching operations and demolition, but not so much for small scale amateur testing. A matter of objective and taste I guess...

[Edited on 19-9-2014 by markx]

hinz - 19-9-2014 at 16:33

That looks nice:
http://www.sciencemadness.org/talk/files.php?pid=346660&...

Use some more cord and print your name.
Makes an awesome doorplate

Bert - 19-9-2014 at 16:34

Heavy cord is good for "springing holes"- If you have a narrow hole in rock or wood, and need a wider one to take the charge you would like to use- Shoot a piece of heavy det in the hole. It will be wider afterwards, no more drilling required.

NICE

Laboratory of Liptakov - 20-9-2014 at 08:06

markx: Very good work. I appreciate anyone who can do hands. Anyone who makes tests. Such people are few. Those that only speak the most. Speaking nobody has invented nothing. You can do nice things.
LL

jock88 - 20-9-2014 at 11:57

Det cord thread here:

http://www.sciencemadness.org/whisper/viewthread.php?tid=142...

Hennig Brand - 20-9-2014 at 16:47

Looks like a nice working fuse & detcord winding machine. It also looks like you have some experience working with motor control. I always wanted to make a winding machine, but never got around to it yet.

How thick is the covering, winding, glue and all?

markx - 21-9-2014 at 11:24

Quote: Originally posted by Hennig Brand

Looks like a nice working fuse & detcord winding machine. It also looks like you have some experience working with motor control. I always wanted to make a winding machine, but never got around to it yet.

How thick is the covering, winding, glue and all?

The core has a diameter of 2mm and the whole cord is 3mm:

The glue does not practically increase the diameter as it mostly gets absorbed into the layers.

jock88 - 22-9-2014 at 12:15

Going a bit off topic I always had a pet project in my head to make /obtain a few hundred meters of det core and let it rip suspended on poles/trees strung out in a somewhat straight line. This would create a sound like thunder as not all sound reaches a spectator at the same time (just like the rapidly expanding channel created by a lightening bolt).
If one were to use ETN how narrow could you go with the center and thus make the cord as long as possible with as little stuff as possible. A pound should make a hundred meters one would hope.

Bert - 22-9-2014 at 13:41

Quote: Originally posted by jock88

I always had a pet project in my head to make /obtain a few hundred meters of det core and let it rip suspended on poles/trees strung out in a somewhat straight line. This would create a sound like thunder as not all sound reaches a spectator at the same time (just like the rapidly expanding channel created by a lightening bolt).

I have had the experience of being perhaps 200 meters from such a suspended det cord shot, with no prior warning- At PGI convention, someone with a severe passive aggressive problem used a long suspended run of det cord attached with many short sections of shock tube, to ignite individual waterfall sticks via shockwave:flame transducers- Thus lighting a large tight wire "waterfall" (Fargo? Can't remember the year).

The audience effect was not like hearing rolling thunder. It was like being HIT by lightning. Everyone was just holding their ears and cursing as the poor waterfall burnt placidly away...

roXefeller - 23-9-2014 at 14:16

At what point should we rename this thread 'det cord experiment'. Really excellent cord though. I wish you would've had more luck than only PETN. Have you tried initiating a charge at the other end of the cord?

Bert - 23-9-2014 at 18:12

Quote:

At what point should we rename this thread 'det cord experiment'.

roXefeller has a point- It could aid anyone searching on this topic.

markx, would you agree to a change of the thread title?

Something like:

Home made PETN det cord via Bickford type spun fuse machine (was "Shock tube experiment")

Or other title of your choice...

PM me if you would like the thread title edited?

markx - 5-10-2014 at 14:09

Just tested the uncoated cyclonite core:

It's a no go at this diameter....

For comparison the PETN core at the very same setup:

roXefeller - 5-10-2014 at 14:20

oooo I like the multicolor thread, kindof like raising the technology to a higher, artistic level. But I'm thinking you could've just grabbed what was available/on-sale.

markx - 5-10-2014 at 23:39

Quote: Originally posted by roXefeller

oooo I like the multicolor thread, kindof like raising the technology to a higher, artistic level. But I'm thinking you could've just grabbed what was available/on-sale.

A colorful coincidence, yes, but not by design

Although there are countless ways to weave a specific pattern for marking purposes. Just it is too much of a pain to reconfigure the weaving machine with separate threads for every different formulation.

[Edited on 6-10-2014 by markx]

hissingnoise - 6-10-2014 at 02:33

Quote:

Makes an awesome doorplate

Indeed, and the art world is waiting . . .

I'm not joking, BTW!

markx - 6-10-2014 at 03:44

Quote: Originally posted by hissingnoise

Quote:

Makes an awesome doorplate

Indeed, and the art world is waiting . . .

I'm not joking, BTW!

Writing immortal quotes into metal with det cord is rather boring and simplistic....imprinting different natural objects (leaves, feathers etc.) into metal with a thin layer of plastique detonated over them, now thats way more awesome

Google Evelyn Rosenberg, she is the grandmaster of the detonographic method. Really cool and unique art.

I have attempted the method on a simple basis, but fortune has not favored these experiments so far. I've had failed initiations and all sorts of just bad luck every time I rig up a piece. But I'm not giving up...it has to work at some point:

And after all the preparations the det cord failed to initiate the plastique....left a nice imprint of it's woven structure along the edge of the backplate and disintegrated the artwork and the charge. If I had folded the cord twice or even three times along the edge of the plastique, then it probably would have had enough impulse to kick off the plastique. Hindsight....sigh...the only true precise science.

plant

Laboratory of Liptakov - 10-10-2014 at 10:10

And what follows. Yes, I know, it's not so nice. The old pot is terrible. The whole thing is terrible. But try it could.
LL

magneet - 10-10-2014 at 11:49

Detonographics are cool. :cool:

initiating such plastick sheet is a hard lesson I know

2 mm core is little in combination with soft shock-dampening twine,
Seems to be the issue with the RDX cord too, if initiated right it might be a go

20% binder is a lot.

markx - 10-10-2014 at 13:32

Digressing from the topic of the thread, but here are the remnants of the same plastique from the failed detonography test (20% inerts are quite ok for PETN based compositions):

Packed behind an "exotic" coin, placed on top of a 13mm steel plate and disposed of in a responsible manner. Leaves quite a mark, especially on the bottom side...the plate is not cast iron, although one could assume that from the coarse cristalline structure.

[Edited on 10-10-2014 by markx]

magneet - 10-10-2014 at 21:28

Nice

Did you try a initiation with the exposed core in direct contact with the plastique?

Hennig Brand - 14-10-2014 at 06:22

Seeing your test made me think that it was time to try detonating some plastic explosive with my own detcord. My own test was also unsuccessful. The plastique used was 81% ETN, 19% inerts. There is a dent in the steel where the plastique was sitting, but that extra effect could have just been from the confinement the plastique provided for the detcord, or possibly the plastique between the cord and steel detonated, but not the rest.

This cord is the same 2m piece that was made in 2011 and discussed here:

http://www.sciencemadness.org/talk/viewthread.php?tid=14204&...

Notice how one half of the detcord is more yellowed than the other half. Each half was made from a different batch of ETN and it would seem that residual acidity was better neutralized in the less yellowed half and/or the ETN in that half was better stabilized. I don't know if it is obvious from the picture, but it is fairly obvious when holding the cord.

[Edited on 15-10-2014 by Hennig Brand]

magneet - 14-10-2014 at 09:54

I think the dent come's from a positive detonation of a small part of the plastique. no plastique tamping effect.
Unless there are other factors to consider like it was inserted into the whole length of the charge, or the cord has no bare cut inserted but was capped or plugged.

probably the major part just snottified before the shockwave ran past the bare cut.

[Edited on 14-10-2014 by magneet]

[Edited on 14-10-2014 by magneet]

[Edited on 14-10-2014 by magneet]

Hennig Brand - 15-10-2014 at 02:23

The cord was run most of the way through the charge. The charge was however very small (~12g) and the impulse from a single strand of detcord is not nearly as powerful as from a number 8 blasting cap (or similar equivalent). The detcord used has about 14.6g of ETN per meter of length at a density of about 1g/cc. This corresponds to about 0.37g of ETN per inch of cord length at the low density (relative to a typical blasting cap base charge) of about 1g/cc. The vinyl tubing, explosive core covering, is about 1mm thick, which is reasonably thin, but still considerably thicker than the aluminum blasting cap casings I normally use. From reading some of the old U.S. army field manuals it seems that even the military issue detcord is normally knotted, or doubled up in some way, where it will be used to initiate secondary explosives. I haven't tested it yet, but I imagine a single strand would initiate dynamite reliably.

[Edited on 15-10-2014 by Hennig Brand]

detonography

Laboratory of Liptakov - 15-10-2014 at 10:18

The first attemp.
LL

Hennig Brand - 15-10-2014 at 10:33

Nice impression you made there.

Regarding dynamite initiation with the homemade vinyl tubing detcord, a test was just performed and it was positive for initiation. The dynamite used was actually nitroglycerine powder (10% NG), so it was not one of the more sensitive dynamite type explosives. All dynamites are sensitive though, relatively speaking. The explosive used weighed 25g and was 10% NG, 10% corn starch and 80% ammonium nitrate. It was lightly tamped to a density of 1-1.1g/cc in a polypropylene pill bottle. An unsharpened pencil was forced through the explosive to the bottom of the casing, making a void, and then the detcord was inserted and the explosive gently packed around it. The dynamite was successfully initiated, but in comparison to plastique it is very ineffective against steel.

[Edited on 16-10-2014 by Hennig Brand]

detonography

Laboratory of Liptakov - 21-10-2014 at 05:37

Detonography 2

Hennig Brand - 21-10-2014 at 06:12

Those look excellent.

magneet - 21-10-2014 at 07:51

Very nice L of L

Looks like a more cost eficient method for amateur detonografy.

Did you tamped the whole thing in sand? or in open air?

detonography

Laboratory of Liptakov - 21-10-2014 at 08:08

The whole assembly was in the sand. Thank you. Further tests will follow.
LL ........... :cool:

wet gypsum

Laboratory of Liptakov - 22-10-2014 at 01:44

As the transmission medium used wet gypsum. Other configurations identical.
LL

Hennig Brand - 22-10-2014 at 07:51

Very nice indeed. I am not that much into art, but I can see how this would have a lot of appeal from an artistic perspective.

Rosco Bodine - 22-10-2014 at 09:50

The art and science of amateur experimentalism

Thanks

Laboratory of Liptakov - 22-10-2014 at 11:32

Thanks

specialactivitieSK - 23-10-2014 at 00:03

Nice golden hue should have, brass plate.
Nice colors should have with heat treated steel sheet.
Interesting would be, copy of images generated with 3D printer and print in sheet metal as detonography.

Small goods.

Laboratory of Liptakov - 23-10-2014 at 06:58

Annealed copper 0.55 mm, distance 50 mm, 12 g NM gelatin, water udder. This set goes to a mechanical press. An attempt was made because: It is necessary to determine the possibilities detonography. The greatest effect is natural leaves, corn and the like.
LL

[Edited on 24-10-2014 by Laboratory of Liptakov]

test

Laboratory of Liptakov - 24-10-2014 at 11:11

Copper 0,55x60x90, water medium distance 60, NM gelatine booster 7g.
LL

markx - 24-10-2014 at 13:07

Ahh...exquicite work!! I take a deep bow to your choice of test object. I have always been facinated by ferns. Primordial entities, primitive, yet so perfect and compelling in their form. There is a legend in my country about the mysterious and elusive fern blossom...a rare occasion of wonder that is believed to accompany the brief passing of midsummers nights when Dusk and Dawn meet to embrace each other for a brief moment to express their undying and everlasting love for each other and then venture apart again for another year to be separated by the dark void of night. It is said that the one who finds the fern blossom in this magical moment may make any wish and it will be granted. And so young people, who still belive in wonders, venture into the forest to look for this elusive cause at every midsummer celebration. I do not know of any who have found the elusive wishgranting blossom, but I do know of many who have found strenght in the idea to make their dreams and wishes come true. I hope that people always keep looking for the wonders around them....for once you close your eyes to the magic, it is forever lost and so with it all the dreams that could lay ahead.

specialactivitieSK - 24-10-2014 at 21:56

Laboratory of Liptakov :

Interesting to test would be Non-Newtonian fluid ( corn starch and water )

Detonography

Laboratory of Liptakov - 25-10-2014 at 00:17

Markx: Fern is fascinating, has a very fine structure.
For SK: That's a very interesting idea. Non-Newtonian Fluid / Cornstarch and water. When used as a dense mass of dough. Gips and water work. Cornstarch Watergel (non explosive of course) will be better. Very good idea. Or any other kind of dough. Maybe dough of wheat flour. (Girlfriend will kill me)
Markx: You would have to try out the dough ...

detonography

Laboratory of Liptakov - 25-10-2014 at 08:05

My home page has pyroforum.org 10th anniversary of its existence. Laboratory of Liptakov printed detonography plaque.
LL

detonography

Laboratory of Liptakov - 30-10-2014 at 00:26

Dry grass field for detonography good material.
LL

detonography

Laboratory of Liptakov - 15-1-2015 at 07:41

And here I attach the phone application Evelin... :cool:

...LL

dangerous amateur - 15-1-2015 at 11:45

Very nice.

Can you explain how your NM gelatin is made?

I have NM and I'd like to have something to cast in shape that's not so liquid.

Bert - 15-1-2015 at 12:29

This?

http://www.google.com/patents/US2338120

Nitroglycerin with at least 15% nitromethane, the NM de-sensitizes the NG and lowers freezing temperature- Then gel with nitrocellulose and use to make various dynamites as usual, of course accounting for reduction in Oxygen.

nitromethane gelatin

Laboratory of Liptakov - 15-1-2015 at 14:40

Nitromethane gelatin: NM 81% + NC2 15% (cont.12,4%N) + 3% Al (use silver flakes for color, no dark german, no spheric) + 1% microballoons. It is better to use not NC2, but gunpowder containing nitroglycerin. In this case gelatin is extremely dense, like jelly. All components, their representation can vary widely. For example, Aluminium 3-20%, NC 6-18, microballons 0,5- 3%. Initiation No.8-10. Attention, gelatin is rapidly losing nitromethane content. Within a few hours. The charge must be gas tight. Hermetically sealed... :cool:

...LL

NeonPulse - 15-1-2015 at 17:48

Quote: Originally posted by dangerous amateur

Very nice.

Can you explain how your NM gelatin is made?

I have NM and I'd like to have something to cast in shape that's not so liquid.

Try this article. the composition described within is probably just what you are looking for. i have tested it myself and found it to be quite satisfactory, especially with added metals both aluminium powder and titanium powder which produced a rather thermobaric like effect.

Attachment: AD0595291(1).pdf (2MB)
This file has been downloaded 715 times

Bert - 15-1-2015 at 18:39

PLX variant made with 5% ethylenediamine sensitizer and 5% a cab-o-sil type thickener?

The PDF refers to the thickener as "Code #1". And mentions several other products as code #2, code #3...

I've access to several types of fumed silica, used for thickening resin, as a bulking and anti caking agent in powders, etc. Manufacturers categorizes them by several characteristics-

Any clue what type/manufacturer's designation the mysterious "code #1" might be?

Bert - 15-1-2015 at 18:54

Quote: Originally posted by Laboratory of Liptakov

Nitromethane gelatin: NM 81% + NC2 15% (cont.12,4%N) + 3% Al (use silver flakes for color, no dark german, no spheric) + 1% microballoons. It is better to use not NC2, but gunpowder containing nitroglycerin. In this case gelatin is extremely dense, like jelly. All components, their representation can vary widely. For example, Aluminium 3-20%, NC 6-18, microballons 0,5- 3%. Initiation No.8-10. Attention, gelatin is rapidly losing nitromethane content. Within a few hours. The charge must be gas tight. Hermetically sealed... :cool:

...LL

How is sensitivity at temperatures down to -30C? Does this detonate when frozen, -29.2 is NM's freeze point.

Which type of microballoons- Plastic? Glass?

Laboratory of Liptakov - 15-1-2015 at 22:40

Sensitivity at -30˚C? No tested. Tested only -5 C, full det. Laboratory of Liptakov not above the Arctic Circle. Fortunately. Glass microballoons, 125 g / liter, standard for epoxy filler.
http://www.havel-composites.com/shop/0-home/129-Mikrobalony-...
... :cool:

...LL

[Edited on 16-1-2015 by Laboratory of Liptakov]

NeonPulse - 16-1-2015 at 00:01

not too sure what code 1 may be. It could be any number of things. It would have to be something cheap since they wanted to blanket mine feilds with the stuff. I tested it using nitrocellulose as the gelling agent and it suspended the metal powders nicely which was all i aimed to do in that instance. Although fumed silica would probably work well i did not want to add inert ingredients other than the aluminium/titanium powders for that particular test

Bert - 16-1-2015 at 13:41

The description of use looks like hydrophilic fumed silica, 5% is a typical ratio for gelling liquids.

The chemical analysis looks... Like diatomaceous earth? The variability of composition (and low price, if they were going to blanket whole fields with it) makes me think it's a natural product.

Beyond that, there's probably other candidates I have not thought of.

for translate:

Laboratory of Liptakov - 17-1-2015 at 02:28

14. All the materials used in the preparation of the newly developed gel are readily available on commercial scale. Code No.1, the only new ingredients introduced in this report, is commercially available at moderate cost. Chemically, it consist of 93-96% colloidal SiO2, + 2,5-3,5 Na2SO4, + 1,0% Al2O3/Fe2O3 + 0,5 to 1,5% volatiles at 800C (300?) (for 1/2 hour). No evidence of nitromethane decomposition due to the presence of Code No.1 has been observed while in storage at ambient temperature for three months or more.

This means that the composition prevents Code 1 (strongly limits) evaporation of nitromethane? I do not believe too. We can only try... :cool:

...LL

PHILOU Zrealone - 17-1-2015 at 10:41

Quote: Originally posted by Laboratory of Liptakov

14. All the materials used in the preparation of the newly developed gel are readily available on commercial scale. Code No.1, the only new ingredients introduced in this report, is commercially available at moderate cost. Chemically, it consist of 93-96% colloidal SiO2, + 2,5-3,5 Na2SO4, + 1,0% Al2O3/Fe2O3 + 0,5 to 1,5% volatiles at 800C (300?) (for 1/2 hour). No evidence of nitromethane decomposition due to the presence of Code No.1 has been observed while in storage at ambient temperature for three months or more.

This means that the composition prevents Code 1 (strongly limits) evaporation of nitromethane? I do not believe too. We can only try... :cool:

...LL

No!
It means that the colloidal SiO2+... (kind of silica-gel) loses 0.5 to 1.5% of its weight upon heating at 300 (or 800) °C...thus this fraction is called volatiles and is more than certainly composed of water; silica-gel being used as dehydratant in food industry packages (tiny pockets with "do not eat" written on it), in electronic devices packaging and in some organic lab dessicator beads (that can be reused/recycled by oven heating...hydratation level is indicated by cobalt salts passing from yellow-pink when dry to blue when hydrated) ... a few years ago it has also found use as luxe kitten-bac filling (cat litter).
--> http://en.wikipedia.org/wiki/Silica_gel

[Edited on 17-1-2015 by PHILOU Zrealone]

deltaH - 17-1-2015 at 11:45

I have some experience with various silicas as they are of great importance as catalyst support. Colloidal silica generally refers to solutions of fumed silica which is kept from clustering and clumping out usually by making the solution mildly alkaline (pH~9 if I remember correctly). Fumed silica is itself commercially available, but the stuff is HORRIBLE to work with because of it's ridiculously low apparent density. It's a bit like goose feathers, just much smaller and you need bags full to prepare a solution... that's why people prefer to work with the colloidal solution versions. A popular brand of colloidal silicas is the LUDOX range made by Grace Industries (brochure attached). Another maker, off the top of my head is Evonik (formerly Degussa).

The silica gel we commonly encounter in drying sachets, kitty litter and the like is quite a different thing morphologically speaking and doesn't have the same rheological properties as fumed silicas. The former is prepared by acidification of sodium silicate followed by ageing regimes.

Attachment: ludox.pdf (731kB)
This file has been downloaded 1778 times

****
Fumed silica is also commercially available in a more expensive hydrophobic form. In this type, the surface has been 'silanated' (treated with a mixture of methylchlorosilanes AFAIK) so that the naturally hydrophilic hydroxyl surface groups are replaced by methoxy groups.

***
PS. The picture on the front page of the brochure I attached is irrefutable proof that chemtrails are made by spraying SiCl4 into the turbine exhaust from airplane engines, i.e. making fumed silica and HCl

[Edited on 17-1-2015 by deltaH]

Bert - 17-1-2015 at 13:07

We used the hydrophobic variety of fumed silica for an anti cake agent in pyro. I recall Cabot making product used in fireworks flash powders. Have to dig for references- There are a lot of different grades by surface area and surface treatments.

Yes, the stuff is a pain to handle or mix with liquids, not so bad for solids. We just shoveled it in for last 20 minutes when milling the Oxidizer/catalyst ingredients of a flash mixture. Ball min would then be full to the top, but the cab didn't keep the charge from rolling properly. 20 minutes later, there was a lot of decrease to the apparent bulk of the charge, and the mixture poured almost like water.

I note that code #2 and code #3 call for parafin oil as a mixing aid into nitromethane. That sounds like a treated product?

Bert - 28-9-2015 at 08:54

Back to the OP and the home spun det cords?

I've been looking at an application calling for a VERY light det cord. Customer specified 4 grains/foot. No one around here admits to stocking, or even KNOWING of such a product- Orica may make/sell something like this, otherwise, nada.

What is the smallest Dia./lightest loading of det cord or similar product anyone has encountered? A nominal 15 grains/foot is about as low as seems to be in common use around here. The OP material is in the ball park at 3.3 grams/meter as well.

If one wanted a true det cord (as opposed to the "shock tube" which doesn't even have the energy to rupture it's plastic caseing), what is the smallest critical Dia. filler HE available- PETN seems to be easily made reliable in cords down to 15 gr/ft., what would allow 1/4 or less of a loading and remain reliable? Has anyone ever made a det cord filled with mannitol hexanitrate, for instance? Bloody awkward crystal shape to run through the filler funnel!

Dornier 335A - 28-9-2015 at 11:13

This is not really useful, but might still be interesting for you Bert. I have made det cord, filled with nano-Armstrong's mixture, containing as little as 0.5 grains/foot (1 mg/cm). It was in the shape of a very thin, flat tube of aluminium foil. Not very durable but then I never made more than 4 cm in length. It goes off without a primer (surprise!) and easily sustains detonation. The filler material has a critical diameter well below 40 µm.

15 grains/foot, assuming a density of 1.5 g/cc is a cylinder with radius 0.82 mm. According to Fedoroff, thin sheets of a 85/15 PETN/natural rubber mixture at 1.4 g/cc detonates down to a thickness of approx 0.8 mm. So stretching your det cord to 4 grains/foot seems a bit too far. I can't find critical diameter values for MHN but does it differ enough from PETN to actually matter?

The only foolproof materials I can think of are some primary explosives, tetrazole derivatives and liquid ozone... The latter has a reported critical diameter of 0.15 mm.

Bert - 28-9-2015 at 13:08

Quote:

This is not really useful, but might still be interesting for you Bert. I have made det cord, filled with nano-Armstrong's mixture, containing as little as 0.5 grains/foot (1 mg/cm). It was in the shape of a very thin, flat tube of aluminium foil. Not very durable but then I never made more than 4 cm in length. It goes off without a primer (surprise!) and easily sustains detonation. The filler material has a critical diameter well below 40 µm.

Ah, I will be needing to HANDLE the stuff, about 10' per shot- Bemding it into a molded in channel in the back of a series of plaster of Paris props. No thanks , even at that low of a loading , accidental explosion of a 10' length at fingertip distance will probably be more than just embarrassing.

I would not care to handle DRY Armstrong's mix- But I COULD see applying a wet slurry of Armstrong's, water and a gelling agent in the bottom of the channel originally specified to model makers in order to hold the det cord. Certainly wouldn't want to handle the dried props after setup!

Shoot is @ 1,200 frames per SECOND. The difference between Armstrong's and PETN cord should be quite striking at that rate of capture.

markx - 28-9-2015 at 15:17

4 grains per foot is really stretching the limit for conventional secondaries...I guess PETN will be your best bet in achieving a goal close to the one specified. There may be some synergic mixtures, but from my experience it is only a theoretical speculation and will not help you further with the practical task at hand. MHN is a rather nasty option really...I have not practically tested the minimal critical diamater of the compound , but I would not be very optimistic about it being much lower than the specific value for PETN. Apart from that it is markedly more unstable due to steric hindrances and poses a significant challenge in the purification stage. A lot of persitant impurities are formed by the mixed acid synthesis route of MHN and this translates into multible purification rounds to get a more or less pure end product. Including primaries into the equation is a very hazardous venture and I would avoid this route if ever possible. Perhaps the client can be persuaded to accept a "more conventional" loading rate for safety reasons? I mean that the lower charge of unconventional or primary material is most likely not safer than a conventional charge of reliable and "more or less predictable" secondaries in larger amount. If unavoibale technical limitations do not pose a restriction in this direction then perhaps it is still the way to go....
And perhaps again, if technical reasons do not oppose the application, then maybe commercial shock tube might do the trick without having to resort to exotic means? Not knowing the exact background of the project these are just some ideas from the top of my head...

[Edited on 28-9-2015 by markx]

ganger631 - 17-10-2015 at 22:57

Quote: Originally posted by Dornier 335A

Hey, are you going to post it on your channel?

No need to re-invent the wheel-

Bert - 27-2-2018 at 15:57

I now realize that Franklyn suggested these years ago.

Many types available, starting around $10 US.

https://m.ebay.com/itm/i-Cord-maker-Knitting-Machine-Spool-K...

For home made bickford style fuse or woven jacket det cord machines, all you would need to engineer is the powder funnel and an agitator or tracer thread spools to ensure even filling, a drive motor and possibly a "snail" to wrap the powder column in a plastic tape just before it enters the tube knitter to prevent powder escape.

[Edited on 28-2-2018 by Bert]

Bert - 7-3-2018 at 00:11

I bought the cheapest variety of these cord knitting machines from ebay,, about $9 delivered.

I also bought a 500 meter spool of fluorescent yellow 10lb. test braided spectra fishing line (ultra high molecular weight polyethylene, AFAIK- this is a VERY strong, slippery and thin line).

I just tested the combination. IT WORKS REALLY WELL.

I tried running various long thin solid objects such as dowels, cords, etc. through the center of the knitting process, it neatly and happily enveloped anything from 1/8" Dia. up to around 1/4" in a knitted tube, it might be able to do larger, but I can't envision making a detonating cord with a core wider than 1/4".

The weave is too coarse for the type of operation the various Bickford fuse machine makers here have done, where granulated black powder falls through a powder die and is contained by spinning on a couple layers of multiple threads at different pitch, or even countersun layers. The fine PETN powder would just fall through the weave this machine knits.

I intend to make a powder funnel and outlet die that feeds finely powdered PETN, RDX, ETN or other suitable HE into the center of a "snail", wrapping the powder exiting the die in a spiral of Teflon plumbing tape. This PTFE tape wrapped HE column would then enter the tube knitting machine and receive a knitted jacket of spectra or kevlar thread to prevent unraveling, also to provide tensile strength and durability.

After the tube knitter, it could be fed through a coating bath of lacquer to lock the whole thing together and water proof it, or through the center of a plastic extrusion die to coat it with a thermoplastic as some commercial detonating cords and blasting fuses are.

One could add a second funnel surrounding the HE funnel, for dusting the PTFE tape with fine Aluminum powder on the inside as it goes around the HE core. Or arrange a second "snail", applying a counter wrap of very thin Aluminum foill or aluminized mylar over the PTFE tape. It would be a shame to waste the oxidizing potential of all that PTFE. Thermobaric det cord?

[Edited on 7-3-2018 by Bert]

markx - 7-3-2018 at 04:15

Nice find, Bert!

Dirt cheap and effective, although the weave really is too coarse to hold any reasonably sized grains on its own. As a final arming coat on the cord it will do just fine I guess...
Perhaps there are some machines out there that weave a tighter structure with more needles? The tape wrapping part might be quite complicated to get to work consistently, but we all love a good challenge

MineMan - 8-3-2018 at 16:05

Yes, please update us Bert....! Still a little confused on how you will hold grains with the weave being so course. Is there a very very thin (.2mm-.5mm)(wall thickness) plastic tubing available that you could wrap around, I wonder?

Bert - 22-3-2018 at 19:44

Stuffing a solid down a narrow tube is not feasible for more than a foot or two, it would have to be a continuous wrap applied at output of funnel, then the wrapped powder core entering the weaving machine to hold the spiral wrap together and provide strength.

I am trying to do too many things at once right now, I'm sitting next to.a stage waiting to do an effect, so have time to look at the forum-

markx - 26-3-2018 at 07:05

I refurbished my fuse weaving machine and now it really works consistently and smoothly. Owning a small lathe really allows one to create fully functional solutions

Fig. 1 General view of the contraption

Fig. 2 Feeding funnel and vibratory agitator

Fig. 3 Lower layer weaver with pretensioning for threads

Fig. 4 Upper layer weaver and entry point for powder (also pretensioned)

Fig. 4 Closeup of the vibratory agitator for consistent powder feed

USB 2.0 Camera-3.26-17;41;54;644.jpg - 69kB

Fig. 5 Cross section of the product with BP core

USB 2.0 Camera-3.26-17;42;59;685.jpg - 95kB

Fig. 6 Anoter view of the product with cross section and closeup from side

[Edited on 26-3-2018 by markx]

Bert - 26-3-2018 at 08:10

Nice. You don't pull a thread or threads THROUGH the powder funnel to ensure powder flow?

Pics of the lathe, tooling? Any brands or models you recommend, I learned to use lathe, mills, precision grinders & etc. about 40 years ago, but have not had access to a good metal working machine shop for quite a while. Pretty well set for wood working and some light welding though.

Just finishing off a workshop building now, might have space for a few new toys.

[Edited on 26-3-2018 by Bert]

markx - 26-3-2018 at 08:29

Quote: Originally posted by Bert

Nice. You don't pull a thread or threads THROUGH the powder funnel to ensure powder flow?

No Bert, I went in the direction of vibratory agitation to ensure the flow, but for some applications it might be more advisable to use the "guide thread" method.
In fact I gave up on using fine powders as the feed (like meal powder)...it was messy, inefficient and produced varied results, none of which were acceptable neither visually nor by function.
I now use slightly granulated feeds that do not create dust or fall through the threads....also they flow excellent and require minimal effort to ensure a constant feed rate. But one must work out the proper granulation technique and adhere to it religiously to produce a constant burn rate. If the powder is too coarse or segregates in the funnel, then a widely varied and unpredictable burn rate can be the result....something that is very dangerous.

markx - 5-4-2018 at 05:54

Quote: Originally posted by Bert

Pics of the lathe, tooling? Any brands or models you recommend, I learned to use lathe, mills, precision grinders & etc. about 40 years ago, but have not had access to a good metal working machine shop for quite a while. Pretty well set for wood working and some light welding though.

Just finishing off a workshop building now, might have space for a few new toys.

[Edited on 26-3-2018 by Bert]

A shot of my small lathe (Holzmann ED 400FD) that I consider to be my best investment so far

I've wanted one for years. It is nothing special and for a serious metalworker this might be closer to a toy than a lathe, but for small tinkering it is just perfect.....it does not weigh a ton, runs quiet like a sewing machine and delivers quite good accuracy after some adjustments. Also it is has some torque to it and I've never felt like it lacks the power to make the cut. I managed to drill a 22mm hole through a steel round stock with this little machine in one go (just a small 6mm guide hole was drilled to keep things centered).