Unconventional Shaped Charges

40g of the cast ETN/TNP mix with a .5g AP cap only partially detted, though I blame bad cap placement and doubtful TNP quality on that.

On a happier note, 11g of ETN/NG plastique in a 2:1 ratio was made into a small ball, and a .5g AP cap stuck into it. It was not nearly enough to cover the cap, so I simply moulded it around the bottom half of the cap, stuck it on the bottom of an unpside down cup, and called it good. It was really quite amazing, I belive I will try this comp in some small shaped charges. Adding a fuel (like some of the dark german Al in my lab) would make quite a nasty mix. It is also extremely mouldable, and holds its shape well. It is like a stiff sugar cookie dough.

I shall try it with some glass liners from lightbulbs, or whatever I can find soon.

My lb of ASA arrived, so I can make some quality TNP to continue with these expirements.

[Edited on 1-2-2006 by Swany]

Lightbulbs certainly work Best lightbulbs are candel lightbulbs (attachement). I achieved 4,7 cm with a such a liner of 3 cm diameter with PETN/NM plastique. They have a good conical shape, but unfortunately they are too thin for a realy good performance. (Because glass is much less dense than copper you need a thicker liner to have about the same mass)

Tricky part is cutting a liner out of them, I used a small string of cotton, soaked in gasoline. After the string stops burning, dump the lightbulb in cold water. It takes a few tries, but it works.

That's from the improvised munitions handbook, for cutting wine bottles for SCs. I doubt it works well for a 30mm dia lightbulb. Would not the flame be at least an inch, heating the whole bulb? How shall it cleanly part in the middle, instead of shattering completely? Why not mechanically remove the bottom, leaving a build-in 2 CD standoff?

Maybe "a few tries" means you used three packs of bulbs before getting one liner?

It realy works, try for yourself. The trick is very local overheating and exansion of the glas, so the string should be as thin as possible, just to hold enough fuel to burn for about 5 seconds...The icecold water makes the glass contract and break. The cut usualy is very clean, but sometimes the glass has some additional cracks, these small cracks don't matter for performance.
I first mark the boundary of the fitting on the glass, then I make a lasso out of cottonstring and attach it about 0,5 cm under the marking. Then I add the fuel (lampoil, gasoline, thinner) and light. I have found that these glassliners glue reasonably well to pvc with pvc glue.
You are right removing only the bottom is a better option, but since I detonate all my charges underground I decided it would be too fragile. I indeed took me 3 lightbulbs before I had a good cone btw, but @ 0.56 cents each is not that much of an expense. It is a lot of work though .
But for me the work is worth the effort. Making a large liner is more easy then a very small one, but a large liner, like the glassfunnels, need a large amount of explosive which is also expensive, hard to come by and more dangerous...(the 3cm glassfunnels give small performance) So for me the trade off is work for less explosive material...

[Edited on 3-2-2006 by nitro-genes]

Just made a clay out of metalpowder, but since I had no copper powder I used zinc instead. I used about 2,5% PIB, extracted from self vulcanizing tape, with about 8% gasoline. The resulting clay was a bit more sticky and less stiff than with motoroil. This was rolled to about 1,5 mm and put over a 5 cm diameter hemisphere. (this was the hard part) Thinner than 1,5 mm might prove difficult so small liners may be a problem, but there is room for improvement of course.
I then waited for the gasoline to evaporate. The resulting material seemed fairly brittle but holds together quite nicely. It isn't strong enough to be separated from the mold I think...

I was quite excited with this result, so I was stupid enough to try to melt the material together with a blowtorch. Of course the zinc powder started to oxidate immediately, so copper powder is a better option I guess. It made a nice blueish flame though.

On the other hand, maybe it isn't even necessary to melt the powder together? Anyway I will certainly give the vitamin C synthesis a try after the exams.

[Edited on 4-2-2006 by nitro-genes]

Well I tried my own cylindrical shaped charge today, but unlike Axt's mine failed miserably.

I made it some time ago. I used black plastic pipe (NBS maybe? Not sure) since I had some sitting around. I drilled a hole through the base, and stuck the 1/2" copper pipe in using two part fast setting epoxy. I then carefully made a round top from that little plastic thing from the inside of a pope bottle lid, and glued that to the pipe using more epoxy. The parts where then pushed together, since glueing wasn't necessary as it didn't leak (and since I had already pulled it apart once already I felt being able to do that again would be helpful).


I measured the volume using some water, and it came out to be 100ml (exactly as I calculated when I designed it on paper).

The target was the cores from two microwave oven transformers, which was roughly 4.5 inches of steel plates about 1mm thick.
At the target site, a small dip in the forest to keep us (me + friendly spectators) safe from anything that might possibly fly out from it, the methyl nitrate was poured in (I was worried it would dissolve the epoxy and plastic, so transported it to the site in a plastic pop bottle), the cap pushed on, and a detonater pushed in through the hole on the top (pressed AP in a metal case from a battery, about 0.5ml pressed AP total, didn't weigh it). It was set on top of the target with high expectations.


Friend tossed me his socks he got covered in mud when he got his shoes stuck in some on the way there, I wrapped them around the charge, and they retreated to our safe spot about 100 feet away (since there was a thick mound and some trees between us and it, we didn't really need to get that far back). When they were ready, I lit the cheapass sparkler fuse and ran like hell. It's really amazing how fast you can run when there is 100ml of methyl nitrate about to blow up behind you.

Anyway, after a wait for the fuse to burn down, there was a flash (despite it being behind a little hill) and the loudest KABOOOOOOOOOOM I have ever heard, which echoed off into the distance for about two seconds. Opps, wasn't expecting it to be THAT loud. Ran back to the target site, grapped the target, and left (and forgot to take a picture! Arg!). The target was rammed completely into the ground, and there was only dirt around it, ie it blew all the stuff on the ground in the first pic away. No penetration.

Got back home, cleaned all the dirt off the metal and put it back together. As can be seen, it bent the metal quite a bit but didn't penetrate at all. There are copper stains on the top piece. If you look closely you can see that the entire thing is slightly curved from the blast. But I wanted a hole all the way through the metal!





I think the problem was either that the blasting cap didn't go in straight when I put it in during field conditions and low visibility as as the sun was setting and the forest was quite dense, or that it didn't quite touch the explosive, or both. The reason it might not touch the explosive is that the blasting caps will just go into it when inserted fully since the end caps have a ridge in them which puts them up an additional half inch or so. Since there was tape on this one, it is possible that I did not push it in far enough to make contact with the explosive. Since methyl nitrate is extremely sensitive to detonation however, it still exploded with a huge amount of force.
Next time I will spend alot more time making sure everything lines up and fits together perfectly before I head out, rather than trying it once or twice and then assuming it will work under sub-optimum conditions.

[Edited on 10-2-2006 by Chris The Great]

Or more likely that the target was laminated and not one solid peice. This could have caused the softer glue between the layers to absorb all that hard faught explosive power. Like if you took ten 1 mm steel plates but put a layer of rubber between each. When you struck it with a 9 pound hammer it would just bounce off!

You should try a much less elastic target A thick solid steel plate next time

Hmm, yes, it would be that. Here are the measurements, and just for the heck of it the calculations.

Total length of the explosive cavity is 90mm, the liner goes up 60mm leaving 30mm overhead space. The outer diamter of the pipe is 13mm. Diameter (inside of the plastic) is 38mm. I didn't fill it right to the top at the site so the "overhead" was more around 25mm. I'll try a 45mm:45mm setup for the next charge, whenever that may be (hopefully soon?).

Jet mass was calculated to be 0.655 grams, travelling at 16,000m/s (KE 84KJ major energy on a very small area), the slug calculated to be 19.845g travelling at 510m/s (KE 2.5KJ). The slug velocity may be off since I assumed methyl nitrate would have a Gurney energy of 2.86 since the brisance is similar/higher than PETN, and that value was used to calculate the slug velocity using vectors and the angles of the implosion process (maybe advanced math is a little helpful in real life).

Frank, the actual jet penetration process happens so fast that whether or not the target is secure or not means nothing. The jet will be through the target before the target even begins moving from inertial effects. Things like movement travel through the target at the local speed of sound, which the penetration process vastly exceeds. The jet is through the target before the rest of the target "knows" it has been penetrated. The force that hit the target into the ground and bent and twisted it is the force from the detonation shockwave that hits it on the sides of the liner, which wouldn't go into the liner anyway. This is also the energy that well into causing the spalling of the metal Axt had in his test. So I don't really care if it gets slammed into the ground, except I did have to dig it out with my hands afterwards.

Wow! I have just learned something new. and it was explained in an excellent manner with plain english. Thanks CTG for that one

Well looking at your measurements and calculations it seems obvious that lack of head height and a bad subcalibration ratio was to blame. I would suggest giving it 1 or even 1.5X the heght of the liner headheight and either use a narrower tube or make the internal diameter or the charge nearer to 50-60mm.

I agree with Frank here, increasing the subcalibration ratio and charge length seems like the obvious way to go. A fixture to ensure that the detonator lines opp correctly could also be beneficial.

Keep up the good work. Hopefully I'll get a chance to test my 54mm hemi soon, then we'll se who's the big dog here

I think i´ll test in the next few days a cylindrical chaped charge with the same like Axt,..but on a 2" thick (~ 5cm) thick steel plate.

I hope it works because the steel plate is fucking heavy....

And the way to the big wood there is a lot of snow...so I am fucked up with my 50ccm motocycle

Thanks man!
Has anyone tried using MMAN (a primary explosive that's so insensitive it needs a flash powder charge to set it off! Perhaps FOX 7 would give some dramatic reults... Or you could do it like the Swedes (military), simply obtain some military grade pentyle, its stable, cheap, reliable, powerful and burns really fast! Very good for shaped charges.

OMG...

MMAN or MAN (dont say monocarbon dioxide do we) is a *secondary* of the UN/GN/EDDN/HDN family. I made some, and am currently working on a cast AN comp with MAN to lower m.p.

Hmm

Well, If MMAN is a secondary, it's an awfully unstable secondary.
Let's simply agree to disagree?
How much does MMAN cost to make?
Is it military, hard, medium, easy or (politically incorrect) to make?

Again...



I first got the impression that the explosive was supposed to go outside of the lining, but on the picture on the last page, the explosive seems to be inside the lining. Which way is it?


[Edited on 30-3-2006 by chemoleo]

"This because it can be set off without an actual explosion, thus it's a primary"

So it detonates without exploding??? And again, it's a fucking *secondary*. Ever made it? You can hammer away on it, and melt/burn it with a blowtorch.

"A shaped charge works thru ... a high temperature ... jet, that ... reaches plasma and burns it's way thru ..."

The jet is not even molten (450C), so NO plasma here. And it does not burn through, but plastically displaces the target material.

Please, some reading before posting might make you look less clueless!

Oh and it's easy to make. Either bubble methylamine gas through nitric acid, then evaporate under vacuum. Or dissolve methylamine hydrochloride
in a slight access of nitric acid, and drive the more volatile HCl gas out. Just don't try to boil to dryness...

[Edited on 3-4-2006 by Boomer]

'...And at day 6, god created the Cylindrical Shaped Charge'

Well, to cut a long answer short, in my many dreams i have found that with identical charge weights, cone geometries, exp compound and stand-off one may expect a 50% loss of efficiency from Al tube to simple PVC. That said, using a particular construction technique results in more or less the same results (give or take 10% penetration depth)

I.e - in my vivid dreams (hmm could've sworn i was there )
HMTD in a Al tube, using Al Pop can as liner @ 30 deg will penetrate to between 2/3 and 1/2 of charge diameter into forklift-tyne (fork). This holds true for 9mm diam, 15mm diam, 18mm diam and 20mm diam. Any discrepencies i put down to density of charge.

As for symetry of construction - in a perfect charge one would find that the
entry/exit holes are highly symetrical and round. Any deviation from this ideal form can be accounted for by a lack of symetry in either the liner or loading density.

In conclusion i use the rough calc of 1/2 cone diam = penetration into steel that a file doesn't want to touch.

6mm with 1gm HMTD, in 9mm id Al - hole diam 2mm
10mm with 5gm HMTD, in 18mm id Al - hole diam 4mm

Lemme know if pics wanted

This week I make somme explosive experimets with my explosive mate in my garden^^ (subsurface).
We think how we can build good cones for sharped charges.
He ore I had the idea that you can heat a glass pipe and stretch it. Than he make the first sharped charge with a straw, some PETN and a self-made glass cone. With it he make a hole in 2mm steal. The exit was a 1mm hole.
After this I made a charped charge too.
Here is a chart of it:
http://s30.yousendit.com/d.aspx?id=29SWSWOVU59SF3PLS4KBPMFWY...
It made a 5mm deep hole into a piece of steal.

[Bearbeitet am 9-4-2006 von Lapis_infernalis]

Sure thing buddy, Okay first things first. Most literature says that you need at least 1 cone diam of explosive above the apex of the cone as this allows the det wave to be more or less flat when it hits the cone (as opposed to travelling in all directions away from the det), following this 1 cone diam(i use cone len) we need to have the length of the cone, followed by about another diameter to allow for the (internal) stand-off, and finally about another 1/4 diam spare at the top above the explosive. - So we need a tube that is about 4 times as long as its internal diameter.

Next, the lit also says that you get a longer and faster jet that particulates after travelling a smaller distance when using 30deg as opposed to anything larger, sooo we only have 1 diam stand-off - this however also means that easy to use
Al becomes more attractive - however due to its weight you need more of it to do the same damage. Simple - use 3 layers instead of 2. Better symetry and weight. Simple.

I also use the idea mentioned somewhere else here or RogueSci about internalizing the standoff this makes for better retention of the cone i.e energy goes into deforming rather than moving it.

Similarly after making such a cheap and nasty construction it would appear to be a waste using an expensive ($1.50) pvc or steel cap - so i use wait for it.... plasticine - has plenty of weight plus i dont really care where it lands (sure behind something is easy, but how many of us can do this with a 'roof' overhead?)

Okay then with this long winded explaination out of the way, lets take an actual example.

Casing: 17mm Id, 20mm Od - 70mm long
Just something i had left over from making rocket engines

StandOff: 15mm section of estes rocket engine
Basically a tube that is a tight fit inside the body to hold the rim of the cone.

Cone: Take a soda can, cut the top and bottom off then cut it open into a large rectangle. Next anneal this on your kitchen stove or any other similar gas flame. Now measure the Id of your casing and multiply this by 3. This is the diameter of the circle that you need to cut out. Cut a _straight_ line from the edge to the middle. Roll up into a cone 3 layers thick and keep the rim as even as possible (3 layers whole way round).

Det: Take 4cm of 5mm drinking straw, seal one end with hot glue, press in ~3cm hmtd then hot-glue in either wires or fuse.

Putting it 2gether: Place cone on a flat surface, press body over the top until cone is in, then press body over you stand-off tube. This keeps everything straight.
Gently pour in hmtd, pressing with a piece of wood or plastic. Do this until you're around about 1cm from top.
Next wrap the plasticine around the lower 1cm of you det, before inserting whole assembly into end of S.C
This both centres your det and provides something for the explosion to 'push against' as the cone is deformed (plasticine weighs plenty more than the 1.4g or so that this cone weighs)
Place on target, light fuse then run like a crazy bastard (keeping a large rock or tree between charge and anything else of value - like yourself )

Well, hope this helps you somewhat and if not, hope the pics make it more clear. (also have vids)Oh yeah, nearly forgot - nope never tried a linear s.c. These puppies are loud enough as it is, plus i'm a lazy bastard and they always seemed like more work
enhzflep...

Haven't got any web-space, additionally i couldn't work out how to attach (if u even can) more than 1 file to a post, so here is the vid of the above holes being made. If quality is too shit i can re-post individual vids or mail them to you. Orig was about 175Mb dvd quality mpeg2 720x576 @ 48Khz stereo
enhzflep

Attachment: SmallSCVid.wmv (445kB)
This file has been downloaded 1811 times

Yeah, good work. Yust a tip, try 42 degrees to save some heights, it is said to give better penetration. Jet speed is not everything (jet mass gets lower at narrow angels).

Although a little finger spanking is in order now (while there's something to spank ): HMTD, being a primary and a sensitive one, is not a sensible choice for the main filler!
Not only can 5g easily remove a whole hand, you will also get much better performance (read 2-3 times) with a denser/faster secondary.

Ask Al, he had it detonate from withdrawing a wooden dowel from a cap. The same happened to me while trying to plasticise it, using very little force while mixing on a wooden board.
What made us survive unharmed are the sub-gram amounts involved!

Ooops. Thanks for the heads-up Boomer. Not that it really makes a huge difference, (with the sister of the mother of satan)but i always test for friction and impact sensitivity. The batch that was used for above tests was found to be unreactive between 2 rough surfaces (anvil & hammer) until a weight of over 1kg (9.8N) was rubbed across it through a distance of 10cm @ about 3 osc/sec. And i can tell you that i sure as hell am never going to be that energetic when pressing something.

Additionally, to reduce friction i always press with a dowel that is sub-calibre by at least 25% of the diam to eliminate those pesky friction conditions.

But you are of course dead right Boomer, it's not a sensible choice, rather silly some might say - but its not through ignorance that i do this. Doesn't always do what i want, but i love my body and am not particularly keen on being covered with part of it. - Hence the 20mm blast barrier and 40cm long dowel attached to another to keep me away from the top and sides of said device.

Btw, what were you plasticizing it with? Not a nitro-aromatic was it? Did a search to no avail. Whenever i want to do that i use petroleum jelly in naptha. It's just a pain letting it dry.

Oh and 'bout using 42deg. Hmm thanx must try that when i get something with less of a mind of its own.
enhzflep..

My first shaped charge

Hello all!

Yesterday I acquired a strong cylindrical Al tube, closed at one end and of internal dimensions: ID 25mm and height 42mm.

Measured with water, it has a capacity of exactly 20ml and thinking this could be the start of a small shaped charge, I set about constucting a suitable Al cone to form the cavity.

Using a circle of discarded pie tin, I cut along its radius to the middle and coiled it around its apex exactly twice to form a near perfect 60 degree apex cone. I then smeared a thin layer of epoxy across the surface of the foil and reformed and allowed to set hard.

Very impressed with the cone as it FAR exeeds what I was expecting to create by hand

It now fits snuggly over the end of my closed Al cylinder to give a finished capacity of 17ml for the SC.


Because of the shortness of the tube and the angle of my cone however, my charge only has a headheight of 0.9 CD. Do you guys think this will make enough of a detrimental difference for it to be worth my while spending an hour forming another cone with a more obtuse apex to correct this?

I am thinking of a liquid explosive for this charge and EGDN, being the most powerful and reliably initiated explosive that I can make, is the probably choice. Besides, I have 40ml dry and clear in the fridge as I type! 25grams of this wonderful stuff should fit inside.

One last thing for now... INITIATION!

I'll be drilling a hole in the top but I've not decided on the best way to construct the small but powerful cap that would be needed to make the best of this charge. Two things are certain. I'll be using HMTD and the det must not protrude too far into the case or i will just make the lack of headheight situation worse! Any ideas?

Oh and what kind of standoff would you guys suggest and do you think that firing this over the 42mm slab of steel I have in mind is being overambitious?!

Thanks in advance.

[Edited on 11-4-2006 by Deceitful_Frank]

To form a cone of one layer using a circle of metal foil you decide on the top apex angle of the cone that you want, subtract from 180 and divide by 2. You then take the cosine of this nubver and multiply by 360 to give you how many degrees of a circle you need to take the cut sides, bring together and form the cone.

A 60 degree equalateral cone is easy as all sides are equal and cos60=0.5, 0.5X360is 180 degrees so just take a half circle or do what I did and wind a cut full circle around twice.

Like you said it isnt easy. I find that theres a certain thickness of foil that corresponds to a certain diameter that is thick enough to remain elastic but thin enough form by hand. Whether or not this ratio is near to the ideal 4% thickness of liner to cone diameter ratio I dont know!

I have no access to copper sheeting but Al foil of great variety of thicknesses. I'll practice with Al for now

As for making the double wound cone strong. At least for this small size, Three minute epoxy is great. I prewound the cone and mixed the Epoxy for 45 seconds. This givs me a good 2 minutes to spread over HALF of the foil circle and slide into shape. I then held it in shape for 3-4 minutes and BINGO! A perfect and strong little cone. As you can see in the picture, I used the surplus 2-3mm folded back around the Al tube.

The cone will be glued into place with epoxy and I'll use duck tape around the base of the cylinder to make all secure and tidy.

PS... I have no PDF.

...update:

I have now completed the conicle shaped charge, glued the cone and drilled the hole for the blasting cap. As you can see from the pic, it is supported on three plastic legs and has a standoff of 1.5 cone diameters or 1.5 inches.

It is the second time I've been at this stage due to constant difficulties making it waterproof. I had to scrap the last cone and form a new one which is better sealed with epoxy. It is also slightly flatter with an internal apex angle of 80 degrees compared with the previous 60. Maybe slightly less efficient but it does give vital extra millimetres internally to address the headheight problem... we will see

I've just now to make the cap. It will be 0.5 grams of fresh HMTD in a strong plastic tube measuring 7mm X 23mm internally. This will be weighted down with Blu-Tak so that 5-10mm of the cap protrudes into the hole at the top of the charge when COMPLETELY full of EGDN. This may cause a ml of overspill but that shouldnt be a problem.

The fuse will be of my own 7-8 second homemade variety and a tin of baked beans 20cm from the charge will serve as a blast witness plate... and to catch any shrapnel!

I started my HMTD synth last night so hopefully just a few more days to blastoff!


[Edited on 15-4-2006 by Deceitful_Frank]

Finally I have found a way to produce perfectly symmetric liners in almost every thinkable shape and size. It does however require a metal spinning or metal turning lathe and a little practise. A lot of work for a liner, but once you have al the equipment, its about 5 minutes to make the liner itself...

I came to the idea when I saw a television program in which coppervases were made by a technique called "metal spinning" A circular metal disc is spun at about 1000 rpm and forced around a form or mandrel with a shaping tool.

Pictures say more than a thousand words:

http://www.coe.ufrj.br/~acmq/spinning/

A friend of mine had a metal turning lathe so I decided to give it a try. The mandrel was made very quickly. I bought me some playdoh, put in one of my remaining candle lightbulbs to get a form. Then I took about 15 cm of scrap 15 mm hollow steel tubing and drilled some holes in it. This was hung in the playdoh form, centered and free from the walls. The form was then filled with polyester and, after hardening, sanded down in the lathe until completely centered.

This was the result:


here an overview of what is needed:


The copper sheet I used was 0,5mm thick, but even 1 mm sheet is still workable. Annealing is very important with copper as it hardens very quickly. It is nothing more than heating the copper until redhot with a blowtorch and dumping in water. This restores the neat arrangement of the metal atoms in their raster and makes the metal very soft and pliable. As copper hardens very quickly again it was nessecary to anneal about 4 times more during spinning.

The result: (base of the cones is not yet equalized)



The cone on the right was one of the first attempts and some circular grooves, due to too much pressure aplied, can still be seen. The cone on the left has a nice mirror sheen and was made after maybe 10 failed attempts. The technique is realy surprisingly simple and doable in 5-10 minutes for every liner! Althought the guy with the website I gave above says it is a difficult technique to master, it only took me about ten attempts. I still have to put the cones to the test, but I don't think a more symmetric liner can be produced this easily.

I do not think many people will actually try it, but if you happen to have or know anyone with a turning or spinning lathe, give it a try!

[Edited on 17-4-2006 by nitro-genes]

The drill press method could work I think for not too large spinnings it would have enough power I guess. 12AX7 might have a point though about the sideway forces. Though a lot of force is directed downwards and the amount of force necessary doesn't appear to be that great at all. (I was quite surprised by this) The annealing makes the copper soft enough to be hand bent and twisted even when 1 mm thick sheet is used!
You would only need to make an improvised toolrest. Be sure though to stay below 1000 rpm, or strange things might happen...

The mandrel and contra mandrel are screwed together with the sheet metal in between. So, the grip is indeed only provided by the contact surface of the mandrel and contra mandrel on the sheet metal. Basically the sheet metal is clamped very tight between mandrel and contra mandrel. This provides enough grip to apply quite some pressure with the working tool.
Only be sure that the contra mandrel has no sharp edges where it contacts the sheet metal. When too much pressure is applied, this is where the sheet metal ruptures or wrinkles. (my first 5 trials )

This is the total picture, the contramandrel is actually nothing more than an adapter between spinning centerpiece and the mandrel itself:


The material of which the mandrel is made does not really matter, I chose this material because it is fast and cheap and I had no idea if it would work at all. In fact a lot of materials can be used, ranging from tropical wood to stainless steel. Steel would make a far better mandrel. Because even after, say 10.000 spins, the steel mandrel would still have exactly the same shape, while wood and plastic mandrels are slowly sanded down by the pressure applied on it with the working tool and thus loose shape.

The technique is a sort of "rowing sweeps". a nice indication is this movie clip. (This guy makes it look real easy btw, I think he has done this more than once )

http://www.franjometal.com/metal-spinning/spinning-videos.ht...

[Edited on 17-4-2006 by nitro-genes]

Yes, I thought the same, the drill presses I've worked with have a long lever which allows a lot of force to be applied. More than enough to firmly clamp the sheet metal.
Another thing that aids in a secure fit of the sheet metal is the slightly rounded curve in the contact area between mandrel and contra mandrel.
And again, surprisingly, there is very little force involved here, in both clamping and working the coppersheet. Copper is one of the softest materials that can be spun. The tremendously fast work hardening is annoying though. You can make about 4-5 strokes in which no force at all is needed, like forming a sheet of lead, and then suddenly it won't do a thing anymore.
I needed 4 annealings for the last cone, but I think it can be done much faster still.

Quote:
You can make about 4-5 strokes in which no force at all is needed, like forming a sheet of lead, and then suddenly I won't do a thing anymore. I needed 4 annealings for the last cone, but I think it can be done much faster still.
---------------------------------------------

I think you might be able to work it longer before annealing if you keep your copper cold where you were working it. I have a cool mist unit and thought it might find good application here. It also would provide lubrication if one wanted to add a water soluble lube. Otherwise a spray of water/alcohol mix would keep things cool.
http://www.cartertools.com/sprakool.html
http://www1.mscdirect.com/cgi/N2DRVSH?PMSECT=2003608

I don't see why you couldn't run a boring bar on the compound and run it in at an angle. Just set it the same as the punch piece, measure the diameter with allowance for the sheet. AFAIK, an hemisphere could be made with a circle cutter or cherry attachment (I always forget how the latter works).

If it's too pointy and tends to pierce, you could make two die sets, one to form the wide diameter and the other to finish the piece. It doesn't have to be in anything too hard, tool steel is only if you're making a hundred thousand or so. You could get away with, heck, get away with oak, or any dense, hard wood, for maybe a hundred cones I bet. Aluminum would be better, at least if it's a good hard alloy, maybe 7075-T6? Same process for cutting any of these including say, steel or cast iron (ooh, messy!).

Heh, using a steel bar and a hole in a chunk of aluminum, a not very well fitting hole mind you, I've punched holes in 24 ga. steel sheet. Not good holes, and not many, but holes...

Tim

This was my idea too at first, but when properly spun, the copper becomes no more than hand warm maybe. I tried cooling with water, but to no effect unfortunately...
I think it's purely the pressure applied with the tool that rearanges the perfect raster of metalatoms and makes it more brittle again.
I do wonder why copper spun in the industry does not have to be annealed that often. I found some moviecllips in which they spin copper into much more complex shapes without 1 further annealing.

Maybe the copper they use is purer quality?! Mine is pretty pure already @ 99%...

[Edited on 18-4-2006 by nitro-genes]

Nice to see more people give it a go...

With the right sheet material and tools, you can go really small...The cones I made had a diameter of only 2,8 cm and would require about 20-25 grams of HE at most...I have no doubt that with some size adjustments to the working tool, even smaller cones are possible! (bigger is clearly no problem) This weekend I will have more than enought time to experiment a little with different shapes and sizes.

The macro setting on my new digital camera clearly works!


I can't wait to give them a try...Unbelievable that I've always had a good source of HNO3, but now the new delivery has failed to arrive... I still have some NM, but it sucks with these diameters. Time to get my vacuum distillation equipment out of the dust again.

[Edited on 18-4-2006 by nitro-genes]

I constructed a conical punch and die a few years ago for making copper cones such as this. I tried flat sheet but it was difficult to work without punching holes in it. Just too hard to gather up and shrink all the edge material.

What I found that worked better then sheet was copper sweat caps from plumbing supply or hardware stores. They are nice and thick and come in many sizes. Of course since they already are cup shaped the amount of forming needed is considerably less.

The whole process of pressing is just more prone to result in errors in lateral symmerty. In my tries with pressing I got a lot of problems too...

One is that when you start to press even slightly off-center, this error will result in on side of the cone being more strechted than the other, thus having more material on one side than the other...
but even with everything perfectly centered I noticed that the copper under pressure has difficulties in "sliding" correctly into place. The mold, or coppersheet is more rough on one side, resulting in one side of the sheet getting stuck. (not very clear explanation) The whole pressing mold should be finely polished and lubricated to overcome this problem.

The beauty of spinning is that, when correctly done, errors in wall-thickness only exist in a circular ring shape manner. But since this does not effect the lateral symmetry of the cone, they do not disturb a proper collapse and jet formation during detonation. Pressing definitely is possible, but if you do have a lathe to make the pressing forms, you're better off with the spinning technique I think..

Btw: spinning is just too much fun really

[Edited on 19-4-2006 by nitro-genes]

It is a bit confusing maybe to post them now, but with my new camera I could finally take some pictures of my results with the 3 cm diameter glassliners made out of those candle lightbulbs... Nothing really of much importance, only that I discovered that more than 1,5 times CD standoff results in a much smaller hole volume with these liners...


It appears strange to me that the 3 CD standoff with the PETN/Pib plastique had the same penetration as the 1,5 CD standoff with the same liner and plastique. Because the entrance hole looks like a mess with the 3 CD standoff, and the volume of the hole it made was also considerably less...
All the other "holes" are my attempts with the 0,2 mm copperfoil.



This is a closeup of the deepest penetration with the 8/2 PETN/NM composition:



And the really slight bumb it made on the other side:



Oh, btw, I've managed to produce about 100 grams of PETN, with freshly distilled HNO3, still have to recrystalize, dry and make it into plastique though. I also have the opportunity of using PETN/NM or PETN/NG, but with these amounts of HE, plastique is much more safe and practical. (After crystalisation I can directly add the Pib/oil coating laquer to the water wet PETN, so no need to handle dry PETN)

I think monday will be the day!

[Edited on 19-4-2006 by nitro-genes]

My first shaped charge

I'd say your main problem was your cap as you described, even with the much reduced standoff you would still get some penetration if the charge fired properly. The lack of headroom is probably the main thing, even 0.25g of poor quality HMTD should have gotten at least a decent detonation from the EGDN.

Also, make 100% sure that the cap is aligned perfectly with the rest of the charge, otherwise you end up with a nice big failure like me

My second attempt.

Ok heres number two...

As you can see it has a better design.
Should be firing it within the next 3-4 so days.

Any thoughts or questions welcome

[Edited on 24-4-2006 by Deceitful_Frank]

[Edited on 24-4-2006 by Deceitful_Frank]

[Edited on 24-4-2006 by Deceitful_Frank]

Frank:

Ah-hah! Looks like a nice improvement. I too tried unsuccessfully many times using an external stand-off. It was not until i used an internal one that i achieved any appreciable damage to the target.

However, i made the mistake of changing two variables at the one time. Namely the internal stand-off, in addition to the liner angle and mass.(Both heavier and smaller included angle)

Interestingly - using a Blasting Jelly with a 1gm HMTD cap made of metal(Al) I was able to cause much less penetration (~1mm) than with 3/4 the amount of HMTD, initiated with just 0.4gm HMTD placed in a flimsy drinking straw(~10mm penetration). In each case the detonator did not penetrate the charge, but merely sat on top of the middle of it.

I too have more tests in mind(today). And will post the pics, and vids when done. They won't sound as good as yours since i will be testing under 40-50cm earth. Btw - How much do you reckon that steel thing weighed? It looks massive - and to see it jump about like that....

Once again - nice work.

Hmm,

I guess you do get what you pay for right?

Tried for many hours to spin a cone from both 0.3mm and 1.0mm
copper sheet and failed miserably. So, I tried a charge using a copper cone, the same as in a previous post I made. The only difference was that I ignored 2 basic rules.

Firstly - the cone was rather thicker than it should have been. It was two layers of 0.25mm copper - instead of 3 layers of 0.1mm aluminium.

Secondly - the stand-off was only 0.25 Charge Diams, rather than the 1.5 I have used previously.

Result?
Frankly quite crap. I got at most 1-1.5mm penetration. This was even less than i got by using just 1gm in a 9mm tube with an internal stand-off of 10mm.(About 6mm penetration)

Calculating for the 1/7th penetration using 5 times the impulse I reckon that this was only 1/35th as efficient as my previously posted vid.

In short - obey established design rules and don't get sloppy. Oh well hope it gives somebody a laugh.

Attachment: Failure.wmv (889kB)
This file has been downloaded 1683 times

Those design rules i spoke of just above.

Like many things are best described with a picture.
enjoy

Thanks for your comments enhzflep

Yes, my second charge deffinately has the edge on build quality and design. I had cut an inch off the top of the tube to reduse its length and was considering reattatching this to the bottom end where I had already glued in the Al vinegar shaker lid but my cheap hacksaw had resuced the cut edges to a burred mess and the whole deal would not have been stable... scrapped that idea in favour of a few balls of blutack to increase the standoff to 1CD.

As for changing variables, my first attempt was such a pitiful failure I'm willing to try anything at this early stage!

As for your blasting gel/HMTD connundrum... 1g HMTD AL tube versus 0,4g HMTD plastic drinking straw? and HMTD versus BG? hmmmm, confusing. The only sence I can make of this one is that NG containing gels at small diameters may well be LESS effective than HMTD! Remember that detonation pressure is proportional to the SQUARE of the VoD. IIRC at small diameters NG or non-milky (containing no air occlusions) BG can go at a mediocre <2000m/s! If pressed well, crystaline HMTD is very likely to go at its full 5000m/s so far as I'm aware.

LOL yes! I saw that too. Sadly on closer inspection you can see that its the camera that moves due to the shockwave. That steel must weigh well over a tonne and I cant move it an inch by hand. I think its very unlikely that the downward force from 17ml EGDN could bounce it off its support.

Nice informative vid there!

Hey dont knock it too much... atleast you had SOME penetration though I spose the disappointment has more to do with the hours spent spinning the cone.
Personally I've decided that I'm not going to bother making my own cones at this stage as it would involve too much time and effort. If I stuble accross a prefabricated cone then I investigate a tube to fit around it.

Firstly I think that you got the cone thickness pretty good on as taking the 3-4% rule, for a 12mm CD this would give 0.36-0.48mm.

The standoff was indeed very short and wouldnt have allowed the jet to elongate and accelerate. Saying that you wouldnt want it to long either as copper spray is even more useless against steel!

Lastly I noticed that you had you tube 3/4' full. It looks to me like its 10mm ID and about 80mm long so we can approximate the capacity as 62ml... hmmm. surely the HMTD couldnt have been that un-dence?
Either way HMTD even at it MAXIMUM pressed density is only gonna give you approx 60kbar detonation pressure at BEST. EGDN gives nearly 200 and ANNM around 110. Clearly there are better and indeed safer choices of maincharge for your experiments :

[Edited on 25-4-2006 by Deceitful_Frank]

5 km/s for HMTD? In you wet dreams unless you press it in a hydraulic press, with heavy steel support around the pipe! I bet with hand pressing you were at density 0.5 or lower, with det pressure of a mere 15 kbar. Thats about the *static* pressure of many HEs!

Using a vice (and NO HMTD!), I found that between 5 and 10 kPSI the pipe will expand/deform already. And this results in only 70-80% TMD (theoretical maximum density = crystal density). For 90-95% TMD you need 30000+ PSI = hydraulics or a BIG vice for a small charge. Go calculate the volume and weight before/after filling.
This is why a cast or plastic (or liquid) filler is best for home brew. The military has the pressing equipment needed, we dont. BTW I bet you had LVD in the EGDN, hence no jet hole. Try a better cap next time, say 1g of something FAST (PETN/MHN) below the HMTD.

And no more primary main charges please! I want to hear more from you

Quote:

Originally posted by Boomer This is why a cast or plastic (or liquid) filler is best for home brew. The military has the pressing equipment needed, we dont. BTW I bet you had LVD in the EGDN, hence no jet hole. Try a better cap next time, say 1g of something FAST (PETN/MHN) below the HMTD. And no more primary main charges please! I want to hear more from you

Quote:

Originally posted by Boomer And no more primary main charges please! I want to hear more from you

Okay, okay. Point taken.

This will be the last one I post (& do with a primary )

Its the smallest (and safest with this choice of filler) that i can do.

I usually make caps with more. I reckon that this had ~0.4-0.6gm of HMTD. Initiation was via a graphite powder slurry over the end of two exposed wires (Hit with 320volts)

Btw - anybody had any luck obtaining erythritol in aus of late? apparently the TGA (therapeutic goods administration) has new regulations which prevent the release of information on how to obtain it (according to www.hillsideherbal.com.au)

Failed Attachment from above post.

Attachment: MicroSC.wmv (841kB)
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Now then, 2500PSI = 1125kg square inch
or 1125kg for 6.45 square cm

Working on an column of 5.5mm diam
5.5mm diam = 0.238 square cm
(0.238/6.45) = 0.0368 (3.68% of a square inch)
so, 0.0368 * 1125kg = 41kg

Now, considering that i pressed at 20kg, i fail to see how this could even be guestimated at a density of 0.5 g/cc?

Hmmmm, sounds good. I don't get nitro-headaches, so that's no issue. Yeah about that post. I apologize for the tone of it, and understood his point (never mind the fact that i never expected anywhere near that VDet from HMTD. Just that that's what it's max is. 'twas actually frank that pointed out the vdet.) I also much preffer more exotic things that HMTD, however with virtually no H2SO4 at the moment, my aim has simply been to improve the design as much as possible using ultra cheap and nasty construction techniques. - it's just that this crap is all i have that goes bang at the moment.
I mean I do have about 4-4.2L left of 50% H2O2 and around 1.5 kg Hexamine just sitting about.
Spose i could always get some hobby fuel, then use the methanol for MethylNitrate and the Nitromethane for ANNM. Now that could be a good use of chems. Only 5-10% useless oil in each purchase
I guess next experiment will be with the geometry and construction technique i have - but filled with a cast AN/HDN mix. Could be somewhat more interesting and safe. After all this is just a hobby that i use to wind-down after work that no-ones paying me for and actually costs money.
Oh, Chris btw - reviewed the last U2U i sent you. That big mess of stars was supposed to be a huge smilie ('case you wondered)

Finally - Managed to locate the cone used in the vid titled "Failure.wmv" check it out. The jet was retarded shamefully by the total lack of stand-off.

Good stuff guys and yes it was I that assumed you could get full velocity from HMTD by hand pressing. Maybe I was typing with a little overenthusiasm but boomer was right, even if he did labour his point abit

I'd just like to contadict Chrises third paragraph where he describes a few properties of his favourite explosive, methyl nitrate.

I've yet to synthesise MN but I as far as I was aware its MORE sensitive than EGDN. I'm not going to quote sourses and I may well be wrong but whatever! This is just the opinion that I've gathered. Whether Chris can quote sources, or has used EGDN and can give a more reliable opinion than me... I dont know.

Secondly, 8000m/s? this seems a little exaggerated to me. I thought urbanski and federoff quoted around 6800 as a maximum, to me this is far more likely given its relatively low (1.21g/cm^3) density.
Maybe it can be over driven in extreme confinement with an 80 gram TNP cap like EGDN?! This is hardly practical if we are going to make use of is tiny critical diameter for small and relatively safe experiments.

As for the matter of detonation pressure... 350Kbar... no way!

Using a well recognised formula to approximate detonation pressure for CHNO explosives with "normal" detonation products:

(VoD in m/s)^2 X Density in g/cm^2 X 2.5
-------------------------------------------------------------------
1,000,000

This gives a goood approximation of 140 kbar! Compare this to HIGHLY pressed RDX 340, EGDN 195, ANNM up to 110, HMTD up to 60 and pure NG... if you are VERY VERY lucky, encase in steel with 3cm diameter and a strong cap, 235

Sure, on paper MN is great but lets not allow our emotions cloud the facts

enhzflep, nice pic of the recovered liner. Must be quite satisfying to see liner callapse for yourself in practice... reassures you that you are deffinately on the right track!

[Edited on 26-4-2006 by Deceitful_Frank]

Unfortunately, I had only very little time too experiment with spinning this weekend. I did produce another nice cone however. It is slightly tulip shaped, going from 60 deg. at the top to 55 deg. towards the base, with a diameter of 28 mm. In the picture it is glued to a piece of 32 mm diameter pvc tubing that acts as a standoff. (55 mm long in this case, or ~2 times CD)



A pvc adapter piece is used as the explosive container with a pvc screwcap.


As the explosive filler is used 33 grams of PETN/pib with 82% PETN. ( I made 50 grams, 41 gram PETN with 9 grams of plasticizer) This ratio results in plastique with better cohesive properties than the 85% and is also less stiff...It may kill the VoD a little more, but with this experiment I just want to see wether the liner functions properly.
I ended up using a little more than the 25 gram I was aiming for, but this is due to the 2 mm subcalibration between the cone and the pvc adapter that was not taken into account. I also measured the volume of the container with water before putting the plastique in and this was 23-24 ml. So density is somewhere between 1,38 and 1,43 which is normal for homebrew...

I will probably fire it this friday at the earliest... (evenings for myself are a rarity these days )

[Edited on 26-4-2006 by nitro-genes]

YEA! Now we're talking! That spinning is very addictive. But mine havn't gotten to the point that I want to show the world yet as I am working with on Al (I don't have a lot of copper right now). It is more fun than I thought.
I personally am frightened of Methyl Nitrate. During WWII I believe it was used by the Germans as a last ditch explos and slave-labour was employed in it's mfg. due to it's "sensitivity"
However it COULD be well behaved if soaked in a filler (a la dynamite). The headache issue is another can of worms. I have heard they are not of this world. But the explos interest I have for plastics can't be denied. The latest issue from LA Labs is the use of VersaGel C-Series MSDS PEN13392 which is essentially a Hydrocarbon polymer! This stuff is the binder for X-9094 and is gelled parrifin oil. Which was Cooper's ideal Hydrocarbon additive. It -=IS=- available OTC from candle mfg concerns around the world. My agenda w/ plastics is that they fulfill the compaction nesessary to make the concepts herein work. Now I suppose that one could also make a sort of plastic w/ HMTD but the whole idea of using peroxides is a scary proposition but what's more I actually believe that there is a lack of consistency when using peroxides due to many features that carry along with their particular sensitivity. One COULD make a dynamite that was consistent quite easily but a peroxcide has a very short window of response & activity that was the same as when created. I realize that the attraction is the simplicity in manufacture but I think alternitives could be found. The Cheddites may be an interesting thing to think over. The use of double-base-smokeless powder would also be worth a try. Either of these would permit the experimenter a margin of safety that permits the focus to be on design - the primary concern.

Nitro-Genes: what's that plastizer you are using there? What are your experiences w/ same?



[Edited on 27-4-2006 by quicksilver]

PLEASE don't make a plastique out of HMTD or AP, especially not with any nitric esters! The stiffer the plastique is, the more pressure sensitive it becomes. As soon as you start to press it..... Plastique from a organic peroxide, like HMTD, is MUCH more dangerous even than the original peroxide alone.

There are so many better alternatives, ETN, EGDN, Methyl nitrate, MHN, NM based plastiques (>4 cm diameter), ANNMSA, PETN, RDX, R-salt, PA, TNT etc, etc and even MAN...Surely one of these must be within reach?!

Btw I just got back at home, after doing a short visit at my friends house. I did only one spin and the result was an even smaller liner. It is about 23 mm in diameter and after a 10% HCL treatment it shines like a mirror!

I tested the 28 mm spun liner with the 82% PETN/Pib plastique today! Notice the 2 ml culture tube as a detonator. It was filled with 1 gram 8/2 PETN/NG and initiated with 60 milligrams of a 50/50 silverazide/PETN coprecipitation with a little silver acetylide on top. It was a great succes, but some things about the results might need some consideration...

This was the setup on location:


I also made a movie of it with my new camera (attachment). I put it on my bike as a fixed support but the strong wind made it move anyway...Unfortunately it is badly compressed also...

This was the result on the 5 cm steel block:

Entrance hole with the carrot still inside:


Entrance hole with the carrot removed:


Exit hole with piece of the carrot on the left:


There was also a larger hole in the ground, about 10 cm deep, but in my excitement I forgot to take a picture...

The entrance hole is really weird, the first 0,5 centimeter deep is like a funnel shape. Opening at 2 cm wide, but then 0,5 cm deeper it narrows down to about 7 mm and stays relatively constant all the way down to the exit point on the other side... Anybody an idea why this is?! Maybe lack of confinement?

[Edited on 29-4-2006 by nitro-genes]

Attachment: 28 mm copper shaped charge small compressed 3.avi (967kB)
This file has been downloaded 2669 times

Just wanted to say this is a really nice picture! Makes you think twice about possible shrapnel...



[Edited on 28-4-2006 by nitro-genes]

Yes of course... Now that you mention it, the tulip shaped glass liners showed the same funnel-like-entry-holes indeed. Strange that Axt's mini-shaped charges made from the bullet jackets don't though, maybe PETN/Pib is too slow for a entirely good focus at the base of the cone. Could be confinement too I think or too little explosive above the cone (headheight), since only 1,5 times cone diameter from the base was used instead of the 1,7 that is optimal...

Would be nice to see how different shapes, angles and VoD's affect penetration depth and the shape of the entrance hole indeed...

[Edited on 29-4-2006 by nitro-genes]