Sciencemadness Discussion Board - Centrifuge for pressing primary

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.

because it makes a massive difference in performance and amounts used. Try reading more info on Detonators and efficiencies, it is well listed across the board of the charts.

Same reason you need to press the secondary.

Amateur / beginner level is lose pack
moderate experience light packed compressed
Experienced Hard pressed = peak performance

Pressed primary pellet and paper carrier

Finished assembly

150mg pellet and paper carrier alone, pressed to apx 100lbs

[Edited on 5-5-2019 by XeonTheMGPony]

[Edited on 5-5-2019 by XeonTheMGPony]

MineMan - 4-5-2019 at 20:14

Maybe off topic but related to gloves, just bough these (and some sleeves):
https://www.mscdirect.com/product/details/07050636
I hope they are a good choice.

The cut and penetration level is what you want. But.. it says they are made from cotton. You really want stainless steel fibers and Kevlar type material.

Yah. I only hand primary’s. But, well. I don’t hardly use primary’s.

twelti - 4-5-2019 at 22:01

Quote: Originally posted by MineMan

Maybe off topic but related to gloves, just bough these (and some sleeves):
https://www.mscdirect.com/product/details/07050636
I hope they are a good choice.

Crud, I only looked at the cut resistance level, which is 5 so how can it just be cotton? Strange... I'm gonna order some of those UHMWPE gloves and compare.

markx - 5-5-2019 at 09:46

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.

MineMan - 5-5-2019 at 13:24

I believe the above is correct. The exception is NPED. Anyways, duds are the most dangerous as they can catch the material on fire. I don’t see a need for over 100mg of primary. Light pressing is all that is needed.

twelti - 5-5-2019 at 21:46

Would it be correct to assume that if using an (energetic?) binder to safely get higher density without pressing, the loss from using the binder would offset the gain due to increased density? Or, can we have our cake and eat it too?

markx - 5-5-2019 at 22:49

Would it be correct to assume that if using an (energetic?) binder to safely get higher density without pressing, the loss from using the binder would offset the gain due to increased density? Or, can we have our cake and eat it too?

Depends on binder, energetic and a load of other factors, but as a rule of thumb one can assume a drop in sensitivity (thus a stronger tendency towards failure) and an increase in critical diameter (thus it might render a small device inert for practical purposes).
What is this mystical "gain" that we actually talk about here? Something that punches through 2mm steel plate vs. something that punches through the same, but with "extreme prejudice"? Depends of course what the objective of your research is, so I'm not suggesting that one should not work towards the sharpest bang in the smallest volume. But consider wether that is really a requirement for your purposes before entering the realm of brute force and high density.
Keeping it simple, thoroughly planned and avoiding strong forces are your best allies. Shield yourself, but within reason.....packing on a kevlar armor suit, two sets of gloves, a massive mask and trying to accomplish intricate tasks by working around a shield that blocks your access shall likely make one very clumsy and provoke dangerous situations as a result. Usually things do not go off on their own, they do go off if strong forces are redirected by mechanical failure and translated into shock loads. And working on the type of compounds that do react without provocation should be avoided like the plague. There are alternatives.

XeonTheMGPony - 6-5-2019 at 04:19

Quote: Originally posted by MineMan

To two of you: There is a reason Industry does what they do, if it wasn't needed I can assure they wouldn't be doing it!

The goal of any one is to ever seek to improve their craft and aim for best efficiency. When you can't press you need to use more of the active material, the more caps you wish to make the more primary and base charge you need to achieve what I and lipkove and others can do with a fraction of the material.

This in practicality means one needs to make and handle more materials, this increases risks across the board far more so then having a good assembly method that involves a press system, why I call this an advanced level, you really can't go further with out inventing some new and novel system.

making the tooling is a one time investment and will last your life, do if you intend to play with this for any length of time you should be investing in the tools to do it safely.

Pressing isn't just for performance either, it all so covers handling safety, it vastly reduces risk of accidental detonations. I do not think you guys have don any serious research into this stuff to be making the statements you're making!

If you just want to linger in the kwel realm of things as you do it rarely then fine, I understand this, but if serious about it there is no escaping pressing, there is a reason why armies and industry do it, it isn't a "fad" of the hobbyist nor a simple obsession, it is grounded on hard data and safety reasons to say other wise is to parade ones ignorance of the field.

To Mineman: You are quite right, there is no need for more then 100mg when one has perfected their art with a good primary and basic good pressing system, even less with a strong mechanical press! As I said in another thread how ever for the start it is better to use more then ideal to ensure initiation as you have stated, best to overdrive then have a fizzle.

XeonTheMGPony - 6-5-2019 at 04:40

A detonators job is to detonate, this is achieved by a powerful impulse transmitted to the secondary.

Rather simple in theory, takes some effort in reality. the #8 cap of old, this was achieved with 3 grams of pressed mercury fulminate and chlorate at 80/20% mixture, this evolved through several iterations befor being replaced by better materials and compound caps.

The goal is a sharp, well focused shock wave, the plate tells us how well we achieved this, I use 3mm plate atm but would like to see the same result through 5mm as this means peak performance, and it will set off any thing out there!

If his goal is to make a initiator then the goal is to have as described above, the only next question is how many.

if just a handful then the kwel method may suite their needs, but given the nature of his question sounds like they want to get to a more professional style cap.

I have found that the 6mm/5.5 OD/ID Cap loaded with 500mg of ETN, Primary being Lead Azide/ Lead Styphnate 80/20% pressed, is sufficient for most energetics the only difference between it and an industry standard cap is a "P" missing.

For added safety you can press the primary into a small carrier sabot by its self, then press that into the shell loaded with the base charge. (This is my method, I use a paper sabot holding the pressed primary, and a small seal of the Base charge on the bottom to fill any remaining space, this acts as a small booster as well)

Attachment: Efficiency of detonators.pdf (759kB)
This file has been downloaded 415 times

Attachment: Initiation and propigation in primaries.pdf (2.6MB)
This file has been downloaded 390 times

[Edited on 6-5-2019 by XeonTheMGPony]

Attachment: Critical diameter of fulminated mercury and Pb Azide Naval report.pdf (3.7MB)
This file has been downloaded 383 times

Laboratory of Liptakov - 6-5-2019 at 07:53

I Agree. 500 mg ETN is enough for in basically any using. Quality detonator with exact charging inside (density, amount) is base key for any next attempts. And not, that every attempt had different detonator. Because on amateur field is often tested sensitivity, or brisance, or the power for secondary, thus own secondary EM, or booster. Is tested is almost always different material. But detonator must be always same. And reliable.

markx - 6-5-2019 at 08:21

Quote: Originally posted by XeonTheMGPony

I do not think you guys have don any serious research into this stuff to be making the statements you're making!

No of course I have not don any serious research into the "stuff".....what on earth made you think along these lines?
I'm just trolling here and trying to give bad advice to keep you all from striving towards excellence.
With your kind permission I shall therefore remove my further presence from these topics.....

twelti - 6-5-2019 at 13:39

@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.

XeonTheMGPony - 6-5-2019 at 19:26

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.

Herr Haber - 7-5-2019 at 03:25

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.

Herr Haber - 7-5-2019 at 03:38

@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.

Laboratory of Liptakov - 7-5-2019 at 10:49

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.... :cool:

...LL

XeonTheMGPony - 7-5-2019 at 16:46

Quote: Originally posted by Herr Haber