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ManyInterests
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I HAD one of those... and I accidentally broke it today! I will be buying another one to replace it.
And yes, I'll be working towards finding the minimal foil. This is for the steel caps (and later the aluminum tube when it arrives). For now I will
focus on processing my shell casings. Punching out the primer is harder than I thought, since I don't have reloading tools (yet). So I drilled through
the back. I noticed that the 7.62x39mm is MUCH thicker than the 5.56x45mm! I broke a drill bit in the process! Another tool to replace! 
| Quote: | | Well done on the tests so far, what was the mass of EM in each of your test caps? |
I'm actually quite proud of my latest test overall. If the new mostly bottomless steel caps can exceed that, then I think I would have achieved my
goal of making a blasting cap that is on par with the commercial or military caps. When I read the Improvised Munitions Handbook section on detonators
(and I should have memorized it better, since it had some information that could have made my life much easier) the warning at the end really
captivated me 'Detonator has considerably more power than a military blasting cap and should be handled carefully'. I don't know why, but just that
made me really, really want it!
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UndermineBriarEverglade
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First cap. 7mm aluminum tube closed with foil. 250mg of ETN hand pressed to 1g/cm3 ( ), plus 50mg loose, detonated with EBW. 1mm steel plate. Bucket of cat litter worked well to muffle sound. I guess I should increase the
charge amount?
 
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Sir_Gawain
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Definitely increase the amount. I would add a third layer of ~500 mg ETN pressed or cast to high density. I used 500 mg melt cast because pressing to
high density in thin aluminum tubes can cause them to deform. I also figured it would help seal the end of the tube.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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ManyInterests
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I feel jealous! That is actually quite impressive for a first time cap. I wish I could have had that kind of result early on!
That being said, I will concur with Sir_Gawain about melt-casting ETN. When you melt-cast powdered ETN and grind it back up again, it is of much
higher density and you will see markedly improved results from similar weights.
For me I am going to make another 10 detonators to test for next time. This time I hope it will be finally... FINALLY the time when I succeed. I will
do 4 steel bodies, all with the ends cut off, but 2 will have just electrical tape at the end to seal the other side (and only one layer) and the
other 2 will have some foiled pressed and some tape to hold that in place. the foil isn't 100% unpushable, but it does need a thwack to get it loose.
I hope that still provides the same purpose as foil.
The other 4 detonators will be 2 5.56x45mm/.223 and 2 7.62x39mm cases all processed as per the Improvised Munitions Handbook. Deprimed and drilled
from the back, so the explosive train will start from the hardest and end in the softest. I will have one of each kind sealed with some foil and
crimped mildly to hold it in place and taped, the other two will just be taped.
The final 2 will be made from the aluminum tube I ordered (which hasn't arrived yet). One with some foil and tape at the end and the other with just
tape.
All loadings will be 1g of pressed ETN and 0.3g of 1:1 ETN:NHN mix as usual.
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Laboratory of Liptakov
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Finally I see pictures with entire assemble with tube. Good work with EBW. On picture is see damage of aluminium cavity. According all is it
full detonation 250 mg ETN. Damage of 1 mm of steel plate is little bit weak, but it can be cause aluminium tube. If should by the tube from steel,
the hole in 1 mm steel would by bigger and rouded. Inner diameter is 7 mm ? 250 mg in inner diameter 7 mm is too small. This diameter require minimal
400 mg of ETN for output segment. ETN should by form a square height...
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Laboratory of Liptakov
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It was create control measurement at similar conditions. Thus aluminium tube 8 mm / 6.3 inner mm of diameter, aluminium foil on output segment 0,1 mm
of thickness, (first pic). Construction steel 1.5 mm of thickness as target. Filling 250 mg ETN output segment pressed on 20 Kg. Primary segment from
mixture CHP/ ETN 1:1 (on pic) and next filling from pure CHP crystalls. Plug from classic BP grain, also pressed on 20 Kg.
Result is very similar. Almost same hole in steel plate......
  
 
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pjig
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Have to ask, but is the bp necessary to get the det train enough temp to get going , or is ematch, or the heat of 1/4” time fuse enough to ensure
100%ignition ?
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UndermineBriarEverglade
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Thanks LL! So nice to have a comparison. My tubes are actually 7mm outer diameter so inner diameter is only 6mm. The height of ETN was around 9mm (low
density). Maybe the aluminum foil layer was too thick or the cap was not pressed tightly enough against the steel.
The next caps, I will use more ETN and maybe a reground melt-cast output segment. But maybe this is already enough to play with secondary explosives.
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Laboratory of Liptakov
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0.3 x 03 x 3,14 = 0,282 x 0,9 = 0,254 cm3 0,250g / 0,254 cm3 = 0,984 g / cm3. Really. Density was 1g /cm3. Next you can try 300 mg ETN high pressed
+ 200 mg for EBW segment about density 1g/cc. Any way, created full detonation using EBW nothing is taken for granted. Is it the successful
itself......
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UndermineBriarEverglade
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Yeah terribly low density. The small (rapid pour) acetone-formed crystals are very fluffy even when pressed hard. 500mg sounds good, I will melt cast
a thin layer and then crumble it up to make the output segment.
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ManyInterests
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With ETN my suggestion is to do at least two recrystalizations. I do the first in acetone, and the second one in methanol. The hot methanol (not too
hot! not at the melting point of ETN!) will make a nice fine powdery texture. Use urea as an acid scrubber in both. I use both urea and some sodium
bicarbonate or carbonate with it as well. This will make sure that no acid is left over in any for your ETN and you will be able to store your stuff
for years without issue.
For me I got an update. My aluminum tube just arrived. I cut out 4 70mm lengths. 2 of which I bent on the other end to hold in 5mm worth of aluminum
foil jammed in (one of them had a rather ugly bend, but there is still a good opening on the other side), and the other 2 are just taped at the end.
Edit: for the ones with aluminum plugs in some take up from 2 to 5mm of space. Is this too much?
I made them longer than needed because I want to make sure I have enough space for the energetic material.
So in the end of the day I will be testing 16 detonators! The final one I hope.
[Edited on 21-8-2024 by ManyInterests]
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dettoo456
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Quote: Originally posted by pjig  | | Have to ask, but is the bp necessary to get the det train enough temp to get going , or is ematch, or the heat of 1/4” time fuse enough to ensure
100%ignition ? |
BP may be enough to decompose and allow for a fast DDT of an ETN segment but it’d be too unreliable to leave it to chance. Time fuse and/or E-match
directly on an ETN charge would be even more unreliable.
A good primary (adjacent to a time fuse or E-match), even in small (<10mg) amounts can help tremendously to sensitize the ETN ignition charge and
ensure a proper DDT to move along the detonator train. If you’re unable/don’t want to prepare 5-nitrotetrazoles, NAP or SADS should work.
[Edited on 22-8-2024 by dettoo456]
[Edited on 22-8-2024 by dettoo456]
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pjig
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Copy that. I was just trying to make sense of why Bp serves any purpose in a det cap. Assuming a 50/50 primary and etn is the 1st segment, I can se
it will raise Temps to hot spot the mix to det. But there is so many other hotter comps to serve this function.
I agree on the standard det train . Primary over secondary.
Some pack 1st a primary,followed by a 2nd segment as the primary/secondary 50/50 then base charge . I assume this is for weaker primaries, or
secondary that need help getting going. Such as a sleepy base (less sensitive).
Teterazoles seem like another rabbit hole to venture.
[Edited on 23-8-2024 by pjig]
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fx-991ex
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The BP is mostly some kind of flame catcher, to make sure everything ignite correctly.
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ManyInterests
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I assume BP means black powder? Would using a simple safety match with nichrome wire wrapped over it also suffice?
| Quote: | | Some pack 1st a primary,followed by a 2nd segment as the primary/secondary 50/50 then base charge . I assume this is for weaker primaries, or
secondary that need help getting going. Such as a sleepy base (less sensitive). |
I do believe we have LL to thank for the 50/50 charge since I have never seen it before he mentioned it to me. For NHN and ETN it seems like a such a
winning combination that I wouldn't bother with any other primary mixture unless I was simply experimenting with it for fun (like DDNP and mercury
fulminate, which I plan on making anyway).
But as a general rule, this has been the case, a lightly pressed primary over a more strongly pressed secondary, for a very long time. I am not sure,
but I think even old 19th and early 20th century detonators that just used a mixture of mercury fulminate and potassium chlorate, probably had two
segments that were pressed at different densities.
For me I am still really excited to see how my bottomless (but double taped) detonators will behave. LL recommended that and I only have seen him use
aluminum foil bottomed ones.
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Laboratory of Liptakov
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Bottomless detonators are used on first page in thread LL8 from Dr. Liptakov.
http://www.sciencemadness.org/talk/files.php?pid=669793&...
Left white, has output segment from pure high pressed ETN. Test runned without any tape. Next is Cu8, next CHP. All pressed on high density, tape was
removed after pressing.
On seconds sides is see pressed black powder used a like plug for electric wire....
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ManyInterests
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Ahh, I didn't look at earlier posts. I might as well read the whole thread again since it has been a while. (someone once mentioned to me that I
needed to press the primary only lightly years ago, but I had forgotten...)
And I am very glad that they perform super well on such thick metal. I hope my ETN detonators do that on my next trip.... I also hope that I didn't
add too much aluminum foil, since it could take some 5mm of space at the bottom. In some caps it isn't 100% blocked a few solid smacks (when not
against a surface of course) could push the foil out, but I guess that still means it is good enough? The bottomless ones with double tape I am not
worried about since I am pretty sure that the tape will not impede the explosive train that much.
My other question: When you made bottomless caps, was there anything you did to keep the energetic material from not falling out? Is simply putting
the cap against a surface, loading it, and then pressing enough to hold it in place or what?
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Laboratory of Liptakov
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My other question: When you made bottomless caps, was there anything you did to keep the energetic material from not falling out? Is simply putting
the cap against a surface, loading it, and then pressing enough to hold it in place or what?....Yes....
Material hold in the open cavity automaticaly and itself. Because is high pressed, arise solid the ingot. Yes, at open design is possible use
nitrocellulose laquer, which create 0,05 - 0,1 mm layer. After drying....
[Edited on 25-8-2024 by Laboratory of Liptakov]
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ManyInterests
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So as I mentioned, maybe I added too much aluminum foil that took up around 5mm of space. Too much or am I worrying too much?
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Sir_Gawain
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Yeah, 5 mm is way too much. You need more like 0.5 mm.
“Alchemy is trying to turn things yellow; chemistry is trying to avoid things turning yellow.” -Tom deP.
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ManyInterests
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OK good, since I didn't load any of the caps I will take out the foil and add less. Good thing I waited since otherwise I would have wasted more
material.
I did make one aluminum cap, around 70mm overall length and only taped at the end. I loaded 1.13g of ETN and 0.34 of primary mixture and it was barely
half full. I don't intend on putting that one against a test plate, but I just want to detonate it while it is lying there, just to see how does.
for using nitrocellulose lacquer. I have NC spray (oxford brand), I might give it a go, but I am content with simple electrical tape.
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pjig
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The only loss you would have experienced ( with too big of a base plug)would be energy lost at base of cap. Side walls transmitting the det energy
laterally. Only an issue in shape charges needing needing energy focused on a conical point to maximize efficiency for a focal point of energy o punch
holes. If the focus of the cap is for initiating general charges, then no big deal.
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ManyInterests
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| Quote: Originally posted by pjig | The only loss you would have experienced ( with too big of a base plug)would be energy lost at base of cap. Side walls transmitting the det energy
laterally. Only an issue in shape charges needing needing energy focused on a conical point to maximize efficiency for a focal point of energy o punch
holes. If the focus of the cap is for initiating general charges, then no big deal.
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My aim is still to make as efficient a detonator as I can. It is a personal goal. I did notice that laterally my caps did a great job. They blew the
sides of the fence bracket apart on a very consistent basis, but I am concerned about one thing regarding brass cartridges. If you look at my images,
you'll see they did a lot less lateral damage than the steel ones. While the brass cases obvious had a much tougher bottom (something which I will
remedy next time by drill a hole through the bottom and having the explosive train start from there) the sides should have still given enough
confinement for a full DDT and blown that apart, too.
Or are the steel cases simply that much better?
edit: I hope the aluminum caps I am trying out won't fail like that. Most commercial and military caps are made of aluminum after all.
[Edited on 31-8-2024 by ManyInterests]
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pjig
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Yes commercial caps are aluminum. It’s an alloy, but one close enough source is spent or 2nd hand arrow shafts . If you know an archery club or some
avid shooters, those al shafts are very good cap bodies. The steel I’m sure is better for confinement, but, If your det train is hot , it’s not
needed. I do like the aluminum ball approach for a base plug. The use of epoxy type materials created too thick of a plug . The aluminum ball can be
sealed with super glue if desired after hammering into place.
[Edited on 31-8-2024 by pjig]
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ManyInterests
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| Quote: Originally posted by pjig | Yes commercial caps are aluminum. It’s an alloy, but one close enough source is spent or 2nd hand arrow shafts . If you know an archery club or some
avid shooters, those al shafts are very good cap bodies. The steel I’m sure is better for confinement, but, If your det train is hot , it’s not
needed. I do like the aluminum ball approach for a base plug. The use of epoxy type materials created too thick of a plug . The aluminum ball can be
sealed with super glue if desired after hammering into place.
[Edited on 31-8-2024 by pjig] |
So adding a dab of super glue on the end will seal it? Sounds good.
For aluminum tubes. I can get fresh arrow shafts that are 7mm OD and 6mm ID, but what about the aluminum tubes that you can buy from aliexpress or
Amazon? The obes I got to test are 8mm OD and 7mm ID giving them more space for larger charges. But they are very soft and easily malleable. I
thought of getting thinner ones but I think they would be too thin at that point.
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