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XeonTheMGPony
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well that's the pellet presses job, is to hold every thing together during the pressing stage, then eject the finished part with my hands no where
near it. the one I showed in pics is a very crude tossed together one, but it works reliably.
the empty paper shell is loaded, then you add the primary and press it, repeat till full, if any remaining volume cap with secondary till it is
completely filled.
once filled and pressed, the bottom is pressed and this ejects it, I usually do this directly into the det tube, then tamp it down (at this point it
is only paper rubbing against the tube walls.
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Herr Haber
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Quote: Originally posted by markx  | | Quote: Originally posted by Rocinante | | There is no reason to press any primary explosive, I fail to see how this strange, exotic obsession became reality. Light force is enough, you don't
need the efficiency the industry is aiming for - lead azide, mercury fulminate, SA.DS, peroxides.... none require any forceful pressing to work
(beyond very slight force). Obviously, having a completely loose powder inside the cap is a no-no. |
I second that! It has long been amazing me.....the constant compulsive fixation on having to press everything "guudentoit" until the seams burst. And
yes.....I do understand full well what it is supposed to accomplish and what purpose it should serve. But trust me, it is totally unneccessary for
practical approach and it does tend to create more problems than it solves. Not even talking about the safety related issues here.
A light touch is sufficient in 99% of cases that fall under the realm of situations the members here might confront in their research. And for the 1%
remaining there are alternatives that do not require the execution of brute force. At least not on the most sensitive primary part.
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There's pressing and pressing.
I'm willing to bet most of you press your primary if only not to have it in powder form wandering about the det casing.
Well, maybe not Rocinante with his 3-4grams TCAP dets...
You dont need to "burst the seams" as it has been said, not even for the secondary but you really want intimate contact between primary and secondary.
And for that you need pressing, even if it's only a few kg to keep the thing in place before you proceed with the rest of assembly.
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Herr Haber
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| Quote: Originally posted by twelti | | @XeonThe MGPony, you mentioned this "sabot" method before. It makes sense to me to press primary and secondary (if you ARE going to press it)
separately, then simply/safely slide them together in a tube. I don't understand why the need for your special pellet press, or how it works. can we
not just press the primary into a "sabot" as you call it, using a small ram, add squib or fuse, then slide that into a larger tube which already has
the secondary in it? Does your gizmo press it up from underneath? Not gettin' it. |
Yes, yes and yes.
When Xeon mentioned whacking his pressed primary I felt a bit... uneasy.
Furthermore, this sabot can easily be made using a paper straw.
Paper straws are now replacing plastic straws and... they can be nitrated !
I'd love to nitrate one of these straws, gently press the primary in it and just moist it with acetone before dropping it down the detonator before
letting it dry.
Benefits: primary hold in place by binder and sabot glued in place if the secondary is ETN.
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Laboratory of Liptakov
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It is also possible pour primary on secondary and shake it down slightly. And then use acetone with 2% - 3% nitrocellulose. Maybe only one drop. And
press. And let it evaporate for an hour or two. (Before closing the detonator). Is necessary try it this operation as separate specimen. Only after
examinate final mechanical properties is posible use for live detonator.... ...LL
Development of primarily - secondary substances CHP (2015) Lithex (2022) Brightelite (2023) Nitrocelite (2024)
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XeonTheMGPony
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| Quote: Originally posted by Herr Haber | | Quote: Originally posted by twelti | | @XeonThe MGPony, you mentioned this "sabot" method before. It makes sense to me to press primary and secondary (if you ARE going to press it)
separately, then simply/safely slide them together in a tube. I don't understand why the need for your special pellet press, or how it works. can we
not just press the primary into a "sabot" as you call it, using a small ram, add squib or fuse, then slide that into a larger tube which already has
the secondary in it? Does your gizmo press it up from underneath? Not gettin' it. |
Yes, yes and yes.
When Xeon mentioned whacking his pressed primary I felt a bit... uneasy.
Furthermore, this sabot can easily be made using a paper straw.
Paper straws are now replacing plastic straws and... they can be nitrated !
I'd love to nitrate one of these straws, gently press the primary in it and just moist it with acetone before dropping it down the detonator before
letting it dry.
Benefits: primary hold in place by binder and sabot glued in place if the secondary is ETN. |
just "whacking it" would most likely end badly, why I say to test and understands your primary is to that reason, tamping, not whacking it or
hammering, pressing ideal, tamping carefully effective but some added risk.
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MineMan
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Xeon...
I understand why you took offense, you have contributed greatly to this thread and have shared the smart methods you have developed. Thank you for
that!
But... clearly Marx and I have done our research,we’re just not as methodical as you and don’t need our detonators to be top guns. I don’t
believe those starting out need to be either.
Industry also uses LA because they have tons of it left over from the Vietnam war... but the explosive industry is also very very slow to change...
even when there are better options out there. Trust ol mine man! I very narrowly lost my life due to one... (saw an excavator narrowly miss it)
Xeon. I cannot really think of many charges that care if PETN is pressed to 1.4g/cc or 1.75. After all 500mg is going to do it... which is exactly the
amount industrial dets use. Already a factor of safety built in obviously since it kicks off the pentolite or emulsion every time...
Xeon, most people don’t have access to the tools you have.
LL and Xeon, I agree for sensitive expierments caps should be as identical as possible with overdrive.
I just don’t like pressing, we know it has been done for ages, we know more pressure actually causes the explosives to be inert... I just don’t
like it and will avoid it at all possible, IMHO this is a very stressful hobby. Maybe it’s not a safety issue just an anxiety issue. But I have
anxiety. And I don’t like pressing caps.
This is too small of a field for use to make our disagreements personal. Marx, your invited back.
[Edited on 8-5-2019 by MineMan]
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XeonTheMGPony
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Dead pressing only occurs in some, MF being the gold example of this effect.
In every paper on conventional caps, compounded lead azide beats all other primaries for handling and initiations (Newer green options are being
developed and look to be good, but moderately complicated syntheses.
I agree the amateur doesn't need the millions of pounds of pressing force, but they need some degree of pressing, and a means to do it consistently,
it is as much for safety as for performance, when blasting rock for road ways there was an adage with dets, you get one free hit (as in if some thing
lands on one odds are you're going to be fine, after that how ever, it got tossed in a bore hole with the main charge) Keep in mind commercial ones
the primary is in a steel tube!!!!
and if one is going to make more then a handful of detonators they need to invest some degree of time to make some tooling to achieve this, all one
needs is access to a drill press, drills, & a file, for the younger crowed most schools have a machine shop. and then some scrap metal. I had a
ton of stuff stolen, so I am literally remaking most of this stuff from scratch and memory, as I get around to it will post here to see how simple
they are, and will post the test blasts as well (simulate an unintentional detonation to prove effective safety of the proposed systems) Some thing
every one should do with their ideas test them irl as what works on paper does not all ways play out in the field!
The aim is to have a safe detonator Assembly system with a very high degree of consistency, and investing in the time to make some basic tools puts it
through the proverbial roof. keep each stage well isolated and focus solely on that stage, IE Bridge wires, then doping the bridges with primary, when
dun put away to dry, then (for me) press primary pellets, set into container with desiccant and in a safe spot, then assemble tubes with base charge,
lay these in a cloth lined baking sheet. assemble when needed
For those wishing to avoid pressing there is the slurry method as well, it was a molded primary based on Mercury Fulminate. There is a military paper
discussing the idea of primaries made into ink and printed to spec.
One could try mixing a slurry and casting it in a paper carrier to achieve the gas seal, reason I prefer the conventional system, is the binder is a
new variable. When time allows I'll take some of my supplies and make a 150mg lead azide slurry and cast it.
[Edited on 8-5-2019 by XeonTheMGPony]
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MineMan
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Sounds good Xeon.
Yes. Commercial dets have a steel sleeve encapsulating the LA... something I would like to find a way to copy in our setting.
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twelti
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Pressing with water
A possibly related point, I read a procedure for PETN synth (including one of the more detailed instructions for ReX I've seen), by "Agent Orange"
whoever that is. It actually has a lot of details in it (solubilities, gas products etc.). In it he says that PETN should be pressed with 10% water
to drive out the air and increase the VOD. It also would be safer for pressing, if you were going to press it - which is why I bring it up here. I
wonder if this is correct? The paper in question looks very detailed, but also says that PETN "explodes when subject to a slight impact". I was not
under the impression it was THAT sensitive (?)
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Laboratory of Liptakov
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PETN is established as secondary. High impact sensitivity is nonsense. You take hammer and try it. The safety matches are sensitive sure more. And yet
are sales in miliard pieces. They have in any tobaccos stands. You can compare.......LL
Development of primarily - secondary substances CHP (2015) Lithex (2022) Brightelite (2023) Nitrocelite (2024)
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twelti
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I DID just find in another SM thread reference to this idea.
Also:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a293530.pdf
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