Sciencemadness Discussion Board - Det Cap Strategies

Det Cap Strategies

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ManyInterests - 17-8-2022 at 09:37

Quote:

Commercial caps pretty much all use pressed RDX which has a critical diameter of about 1mm, cast ETNs critical diameter is probably about 8mm from what I've personally seen but others say 5mm.

They also generally use an unnecessarily large amount of lead azide as the primary instead of NHN and an aluminum tube rather than plastic.

I'm not sure how fast NHN undergoes DDT or its critical diameter but I know it's not nearly as fast as lead azide or as small of a CD, it's certainly a lot more powerful though.

The size of your cap is roughly the same as a commercial #8 but that's where the similarities end. With all that said I'm thinking they'll work.

Dr. Liptakov is the God of caps on the forum, funny he hasn't commented on your design.

So the inner diameter of the cap is 6mm. I know this because I got a wooden dowel from an arts & crafts section that is of that exact diameter. I think commercial and military blasting caps are 6 or 7mm. The very bottom might be less since the end-cap is not completely straight. That shouldn't be a problem with melt-cast though.

From my experience NHN will go DDT in the plastic pen body. Though I need to actually find a place where I can safely set them off on the regular to make sure it will do consistently. In grand total I set off 4 blasting caps. 1 (my first) was absolutely powerful, the 2nd one appeared to have a partial detonation (reason unknown) the 3rd was also partial, the 4th went full detonation, but due to the degradation of the ETN (likely due to acid remaining, even after recrystalization).

So far I don't see any degradation in my cap, and it has been quite a few days. If i was working with my previous batches it should have shown some issue by now, but I see nothing, and that is good.

I should take more pictures instead of relying on memory, but I do believe nothing is going wrong. If there is some change, the barrier I put through should prevent it from being significant.

Also I just learned what critical diameter is... More info?

OneEyedPyro - 17-8-2022 at 13:59

ManyInterests

DDT takes a bit of distance or run up so to speak before the explosive reaches full detonation velocity, that distance varies with different compounds.
Maybe the NHN isn't consistently reaching full power by the time it hits the ETN, I only have a bit of experience with it though.

Critical diameter is simply the diameter an explosive must be to reliably maintain a consistent detonation.
Think of a mile long tube filled with an explosive. At or above its critical diameter it will consistently detonate from one end to the other in the same amount of time. Below the critical diameter it may have an erratic detonation velocity and possibly just fizzle out completely somewhere along its journey or barely go off at all.

I'm thinking the NHN not reaching full power is the culprit for the weak detonations.
Maybe try firmly hand pressing a little bit of powdered ETN on top of the cast ETN with your next batch of caps.

Also, I'm quite certain NHN and ETN are entirely compatible with each other. Maybe someone else can weigh in on this?

[Edited on 17-8-2022 by OneEyedPyro]

ManyInterests - 17-8-2022 at 15:52

Quote: Originally posted by OneEyedPyro

ManyInterests

DDT takes a bit of distance or run up so to speak before the explosive reaches full detonation velocity, that distance varies with different compounds.
Maybe the NHN isn't consistently reaching full power by the time it hits the ETN, I only have a bit of experience with it though.

Critical diameter is simply the diameter an explosive must be to reliably maintain a consistent detonation.
Think of a mile long tube filled with an explosive. At or above its critical diameter it will consistently detonate from one end to the other in the same amount of time. Below the critical diameter it may have an erratic detonation velocity and possibly just fizzle out completely somewhere along its journey or barely go off at all.

I'm thinking the NHN not reaching full power is the culprit for the weak detonations.
Maybe try firmly hand pressing a little bit of powdered ETN on top of the cast ETN with your next batch of caps.

Also, I'm quite certain NHN and ETN are entirely compatible with each other. Maybe someone else can weigh in on this?

[Edited on 17-8-2022 by OneEyedPyro]

Duly noted on what critical diameter is.

Also this cap I made is the first ever cap using melt-cast ETN. All previous ones were purely done with powdered ETN.

Also I believe that the reason why I had degradation in my last batches was due to the acid. I don't think that NHN and ETN have issues with each other. But maybe I will make a test cap (with no igniter. Just a dowel secured on top with tape) and no separator between the two and monitor that. The fact that it isn't sealed will allow me to either put an igniter later or just tap out the material for neutralization.

I'll make a cap like that tomorrow. Very small quantities. I'll photograph it and keep photographic evidence on a daily basis.

Bert - 22-8-2022 at 06:31

Quote:

I need to actually find a place where I can safely set them off on the regular to make sure it will do consistently.

Get a couple of 5 gallon plastic paint buckets. Get enough fine sand to fill about 3/4 full, make sure to pre screen it and ensure all sand will all go through about 20 to 30 mesh. Make a screen up to fit bucket top with the size mesh your sand will easily pass through to reclaim any resulting cap fragments/duds/partial dets.

Put about 1/2 of sand in bucket, level off surface. Place cap and any witness plate, etc. in center of bucket. Carefully pour in rest of sand. Place in a safe area, get behind barricade. Fire cap electrically. (small "TOONK" noise unless you have gone WAY over #8).

"Boomer" used to do this in a CLOSET. In his occupied apartment building. I DO NOT recommend that, test outdoors

Laboratory of Liptakov - 22-8-2022 at 08:13

In an apartment building, you must use a hammer drill. And testing of charge while drilling into the brick.

Microtek - 23-8-2022 at 00:33

I would recommend Liptakovs original method with wood chip. In my experience it muffles the sound better than sand, and works well up to about two grams of HE. In neighbouring appartments it will sound like you dropped something heavy on the floor.

ManyInterests - 23-8-2022 at 23:25

Quote:

I did that before. I believe I posted the results of my first test (5 gallon bucket, filled with inflammable cleaning dust. Mildly expensive, but it is safe) and the results were frighteningly powerful, with just a 0.5g ETN (gently hand pressed) and 0.2g of NHN (also hand pressed). The bucket jumped up, the cover flew off, despite putting another bucket on top of it and it even made a small hole in that bucket.

I was legit afraid of using a bigger cap in that bucket because my worry is that it will bust the bucket. 0.5 grams of ETN is basically a #8 (as it is almost as powerful as PETN, and I believe they use 0.45g of PETN in a modern #8 cap) but right now I have 0.5g of melt cast ETN, topped with 0.3g of hand-pressed ETN and 0.3 grams of NHN as the primary. That is beyond what a #8 is.

I don't have the bucket with me (it is stowed away at a different place) but I don't want to try it in my apartment for those reasons. I can take it out to a park or some relatively remote place where no one will hear the pop in the bucket, and if the bucket does break. I can bring some large garbage bags to pick up the pieces and the dust and just walk away with no one being the wiser.

I do want to try a metal witness plate, as LL recommended before, to see what my caps are capable of.

LL I am also working pretty hard to make some CHP as I promised. I just need to make ammonium perchlorate. I only need to make sodium perchlorate from the chlorate I made. Having some issues, but it isn't anything I can't overcome.

I have some questions about caps using CHP. I know you said that CHP works well alone and doesn't need ETN or PETN as a booster. But how much do you put in a cap? Do you hand press? How much and how hard? Does CHP melt cast? What is the loading density you recommend? I know you've used metal cap bodies, but I will experiment with my bic round stics.

Oh and one final note. It's been more than 10 days since I made my cap, and I see no degradation of the ETN or NHN in my cap. So far it seems like I have a very stable formula! I'll still give it another 20 days before looking for a good place to set it off in the bucket (with the witness plate).

[Edited on 24-8-2022 by ManyInterests]

B(a)P - 24-8-2022 at 02:49

Quote: Originally posted by ManyInterests

I have some questions about caps using CHP. I know you said that CHP works well alone and doesn't need ETN or PETN as a booster. But how much do you put in a cap? Do you hand press? How much and how hard? Does CHP melt cast? What is the loading density you recommend? I know you've used metal cap bodies, but I will experiment with my bic round stics.

[Edited on 24-8-2022 by ManyInterests]

I think you will find most of your answers on the first page of this thread.

https://www.sciencemadness.org/whisper/viewthread.php?tid=158259

Laboratory of Liptakov - 24-8-2022 at 04:47

CHP require solid metal cavity for full DDT. If you change the cavity for plastic or some else, CHP will not works. Others parameters and setting are described by thread LL8.

ManyInterests - 24-8-2022 at 12:53

Quote: Originally posted by Laboratory of Liptakov

CHP require solid metal cavity for full DDT. If you change the cavity for plastic or some else, CHP will not works. Others parameters and setting are described by thread LL8.

I'll review it. But that is duly noted. When I make do CHP ones I will use tubes such as these: https://bit.ly/3TenykA

karolus28 - 24-8-2022 at 13:08

Quote: Originally posted by ManyInterests

I'll review it. But that is duly noted. When I make do CHP ones I will use tubes such as these: https://bit.ly/3TenykA

the link shows me a 404, could you post another one?

B(a)P - 24-8-2022 at 15:03

Quote: Originally posted by karolus28

Quote: Originally posted by ManyInterests

I'll review it. But that is duly noted. When I make do CHP ones I will use tubes such as these: https://bit.ly/3TenykA

the link shows me a 404, could you post another one?

These work well when brass is compatible with your composition/s.
They are widely available in hobby stores.
https://www.hobbytools.com.au/brass-rnd-tube-5mm-od-x-44mm-wall-x-300mm-12-3pc/
BRASS ROUND TUBE 5mm OD x .44mm Wall

ManyInterests - 24-8-2022 at 15:08

Bleh, I hate it when it does that. I won't post a link since those always get screwed up, I'll post the search term:

5 pieces OD 6mm OD 7mm OD 8mm SS304 One End Round head Closed Stainless Steel Thermowell Thermocouple Protection pipe L30-500mm

Search for that on aliexpress.com, it should be the first to come up.

[Edited on 24-8-2022 by ManyInterests]

ManyInterests - 30-8-2022 at 21:53

My previous post didn't make it due to file size...

So it's been nearly 20 days since I made the cap. Is it just me, or is there some very, very slight yellowing happening on some small portion of the ETN. I think this has to do with the fact that there is a hair that made it into the cap by accident.

At any rate, I don't think it'll do much to hinder the cap's performance it is very paint and only affects a very small part. The melt-cast ETN is completely intact. I think it is the hair that's doing it.

MineMan - 31-8-2022 at 02:19

Quote: Originally posted by ManyInterests

My previous post didn't make it due to file size...

So it's been nearly 20 days since I made the cap. Is it just me, or is there some very, very slight yellowing happening on some small portion of the ETN. I think this has to do with the fact that there is a hair that made it into the cap by accident.

At any rate, I don't think it'll do much to hinder the cap's performance it is very paint and only affects a very small part. The melt-cast ETN is completely intact. I think it is the hair that's doing it.

Your over thinking this. PETN, and nickel AG perchlorate. In plastic so no shrapnel. No need for melt cast. It’s a cap. Perfect is always the enemy of good

OneEyedPyro - 31-8-2022 at 04:22

Quote: Originally posted by ManyInterests

ETN always gets a bit off white when cast due to heat decomposition.
Assuming you properly neutralized it you won't see any further changes.

As far as the hair goes, it tells me that you are possibly being a bit sloppy and careless. A hair isn't going to cause decomposition.

Remember that this hobby is very unforgiving, there's no time to react when things go wrong.

It's usually that 1% that will bite you and the other 99% that didn't which makes you complacent enough to get bit in the first place.

ManyInterests - 1-9-2022 at 18:27

I am extremely aware that it only takes one mistake to fuck your life up (or end it). The only error I made in construction here is the fact that there is a hair in there. Everything else went almost perfect.

For future caps I can make the design smoother and cleaner.

If that is the case with the slight yellowing, then I guess I am good! A working blasting cap that I should test at the earliest opportunity.

And I am very confident that all acid has been neutralized, even before I recrystalized the ETN. I washed the ETN numerous times with water until I tested the pH as neutral, then I washed them again several more times for good measure. Then I recrystalized them after they fully dried and washed them some more. I'll be a monkey's uncle if there's any acid left.

Last time I am confident that I didn't fully neutralize the acid, which is why it turned a sawdust brown. This is not happening now, which is a good thing. Also the melt-cast ETN has not changed at all, only the loose powder seems to have a very mild change. The NHN is also completely intact.

XeonTheMGPony - 15-9-2022 at 03:26

Quote: Originally posted by ManyInterests

I am extremely aware that it only takes one mistake to fuck your life up (or end it). The only error I made in construction here is the fact that there is a hair in there. Everything else went almost perfect.

For future caps I can make the design smoother and cleaner.

If that is the case with the slight yellowing, then I guess I am good! A working blasting cap that I should test at the earliest opportunity.

And I am very confident that all acid has been neutralized, even before I recrystalized the ETN. I washed the ETN numerous times with water until I tested the pH as neutral, then I washed them again several more times for good measure. Then I recrystalized them after they fully dried and washed them some more. I'll be a monkey's uncle if there's any acid left.

Last time I am confident that I didn't fully neutralize the acid, which is why it turned a sawdust brown. This is not happening now, which is a good thing. Also the melt-cast ETN has not changed at all, only the loose powder seems to have a very mild change. The NHN is also completely intact.

add tiny amount of urea during the recrystalization, the scavenger helps.

ManyInterests - 15-9-2022 at 18:49

I will re-recrystalize it then. There's no rule saying you can't do that.

I noticed a very strange thing... there was a net weight GAIN after the recrystalization. I never saw that happen before.

Edit: I also found a tube cutter at a local thrift store. I should be able to cut my own tubes now instead of buying premade ones. I saw LL flatten one end partially and then cramming a small of aluminum foil into the other to completely seal it.

Still for my NHN and ETN caps I will continue to use plastic bodies for now.

[Edited on 16-9-2022 by ManyInterests]

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