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Author: Subject: Det Cap Strategies
FeedMe94
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[*] posted on 5-4-2019 at 07:26


My det casings are 6mm x 50mm. Today i detonated 0.8 PETN with 60mg SADS. The second test failed and a friend told me about critical diameter of PETN which is 9mm. If thats true how did the first detonator went off ?

https://ibb.co/gJ18FnS
https://ibb.co/4ShDxLr
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Laboratory of Liptakov
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[*] posted on 5-4-2019 at 07:55


Whats the question? Critical diameter (minimal diameter of a rod that can sustain detonation propagation): 0.9 mm for PETN at 1 g/cm3, smaller for higher densities (other value: 1.5 mm)
https://en.wikipedia.org/wiki/Pentaerythritol_tetranitrate




Safety explosive Alfred Nobel 1867. Safety ecologic detonator Dr. Liptakov 2015.
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FeedMe94
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[*] posted on 5-4-2019 at 08:06


Sorry but my English are not good. Critical diameter is the lowest diameter of the detonator case that will allow PETN to explode , right ? My case is 6mm and still detonated
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MineMan
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[*] posted on 5-4-2019 at 20:52


Quote: Originally posted by FeedMe94  
My det casings are 6mm x 50mm. Today i detonated 0.8 PETN with 60mg SADS. The second test failed and a friend told me about critical diameter of PETN which is 9mm. If thats true how did the first detonator went off ?

https://ibb.co/gJ18FnS
https://ibb.co/4ShDxLr



Your friend is wrong. Industrial detonators use PETN in 6mm!!! PETN works in detcord which is 2mm. You need more or a better primary.
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FeedMe94
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[*] posted on 5-4-2019 at 23:04


Quote: Originally posted by MineMan  


Your friend is wrong. Industrial detonators use PETN in 6mm!!! PETN works in detcord which is 2mm. You need more or a better primary.


I thought SADS was a good primary. At the moment i can only have TATP and SADS
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Rocinante
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[*] posted on 6-4-2019 at 13:05


just use more, at least 170 mg
be warned, tho... SA.DS does degrade if not well sealed and isolated (10 days+)
SA.DS will degrade from direct contact with PETN, esp. not recrystalzed... the remains of sulfuric acid will convert the surface of SA.DS....
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Laboratory of Liptakov
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[*] posted on 6-4-2019 at 13:19


SA.DS is best primary between classic materials. But is weak. Has 3460 m/s at best density. Is it not some great. Lead azide has 5200m/s. And commerce filling is 300 mg. Therefore your det. device are no-reliable with 0,06 SA.DS. Thats clear...:cool:...LL



Safety explosive Alfred Nobel 1867. Safety ecologic detonator Dr. Liptakov 2015.
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XeonTheMGPony
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[*] posted on 7-4-2019 at 13:05


Quote: Originally posted by Laboratory of Liptakov  
SA.DS is best primary between classic materials. But is weak. Has 3460 m/s at best density. Is it not some great. Lead azide has 5200m/s. And commerce filling is 300 mg. Therefore your det. device are no-reliable with 0,06 SA.DS. Thats clear...:cool:...LL


Commercial is an 80% Lead Azide and 20% Lead Styphnate

In a re-enforcing cap pressed it can be as low 100mg.

But for some one new with out much practical experience best never go below 300mg of primary till you develop some basic tooling.
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Laboratory of Liptakov
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[*] posted on 7-4-2019 at 13:18


My word, same opinion. On amateur field with amateur cavity is better always use 300 mg for any primary compound.



Safety explosive Alfred Nobel 1867. Safety ecologic detonator Dr. Liptakov 2015.
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MineMan
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[*] posted on 7-4-2019 at 15:10


Did you follow the correct procedure for SADS?! Preparation effects power. Mix 20 percent PP in. Should only need 50-100mg. Make sure you have 100mg of loose PETN on top of your pressed PETN. SADS will do fine. Is your product white as snow? Because mine DDTs in under a mg.

Make sure you read the section in Primary Explosives.... synthesis temp is VERY important.

Also. Why not just make CHP or TACP with glycine??
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FeedMe94
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[*] posted on 7-4-2019 at 21:08


Is not pure white but detonates unconfined even at 1mg. Cannot make CHP or TACP cause i don't have AP
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Herr Haber
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[*] posted on 8-4-2019 at 08:04


300 mg ?!

When ETN / PETN is initiated by as low as 20mg that seems like massive overkill.
Ok, 20mg is not practical because it's to small and or / might mix with your secondary if not correctly pressed.
But 300 ?
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[*] posted on 8-4-2019 at 08:12


Regarding pressing of either primary or secondary, is it not possible to press it slightly wet, and then include some desiccant inside the (sealed on both ends) det cavity? Seal, crimp, or whatever, and let the energetics dry internally?

Second: Does anyone know if there are incompatibility with epoxy glues and SADS or ETN/PETN? Seems like I read some story about someone who left out some epoxy with peroxide ini it and his dog stepped on it. Yikes!
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XeonTheMGPony
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[*] posted on 8-4-2019 at 14:22


Quote: Originally posted by Herr Haber  
300 mg ?!

When ETN / PETN is initiated by as low as 20mg that seems like massive overkill.
Ok, 20mg is not practical because it's to small and or / might mix with your secondary if not correctly pressed.
But 300 ?


For some one just starting it is better to go massive over kill to ensure full initiation, Vs some one ending up with a live fissled cap sitting on top of a main charge!

As they gain practical experience they can start going smaller as they learn the art n science of dets.
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[*] posted on 8-4-2019 at 21:17


Xeon says wise words. For beginners is better bigger cap-charges with lower density. And step by step, with bigger experiences and quality cavity and tools is possible go to on on smaller det. cap with high density.



Safety explosive Alfred Nobel 1867. Safety ecologic detonator Dr. Liptakov 2015.
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Herr Haber
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[*] posted on 9-4-2019 at 03:26


You are both of course absolutely right :)

Thank you for reminding me that this can happen.
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FeedMe94
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[*] posted on 9-4-2019 at 05:49


You are both absolutely right , like Herr said. As always !!
Science madness is the best school i could ever attend
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[*] posted on 9-4-2019 at 15:18


Quote: Originally posted by twelti  
Second: Does anyone know if there are incompatibility with epoxy glues and SADS or ETN/PETN? Seems like I read some story about someone who left out some epoxy with peroxide ini it and his dog stepped on it. Yikes!


I've read that story too. It wasn't completely clear whether the epoxy reacted and made the compound more sensitive, or if it was just a mechanical effect of holding it together in a brittle block. peroxides are pretty sensitive already. As far as nitrates and acetylides are concerned, that's a really good question-that I don't know the answer to.

https://www.thevespiary.org/rhodium/Rhodium/www.roguesci.org...

Incidentally, Does anyone know if that archive is a complete copy of the roguesci forum, or are there other threads that did not get incorporated into the mirror?





Put that in your pipe and smoke it!
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twelti
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[*] posted on 14-4-2019 at 14:36
tubes


So, I think I understand the reasoning for metal tubes. Protection of the inside, and possibly confinement for some materials. Aside from the confinement issue, I'm guessing that commercial dets must use sturdy metal tubes since they never know what handling there may be in the field - transportation, construction sites, etc. BUT for me, I only need to make it from my basement to the back yard (or in the near future to a bucket on sawdust IN my garage - a la Liptakov). In an extremely controlled environment like that, is there any advantage to metal tube? Does the confinement around the sides, together with minimal confinement on the business end add to the initiating power?
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[*] posted on 14-4-2019 at 22:39


With the exception of shrapnel, the solid cavity contributes positively to all necessary parameters for the detonator. Reliability, durability, easy filling and so on.....:cool:...LL

berta on 4mm.jpg - 588kB




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Herr Haber
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[*] posted on 15-4-2019 at 05:37


@Twelti: Factors affecting the efficiency of detonators.
Get that pdf from the library. It was truly an eye opener for me. This should help you answer some of your questions.
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twelti
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[*] posted on 15-4-2019 at 11:18


Quote: Originally posted by Herr Haber  
@Twelti: Factors affecting the efficiency of detonators.
Get that pdf from the library. It was truly an eye opener for me. This should help you answer some of your questions.


Very useful, thanks. i wonder if it can answer the question: is a smaller metal tube det more or less safe as a larger less confined det of same initiating power? I'm sure that depends on many other factors.
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[*] posted on 16-4-2019 at 04:35


I'd say that with a smaller tube you'll make a more efficient detonator that what you'd do in a larger tube with less confinement and lesser density.

If it's less dense it's VOD will be lesser and will probably be "safer" to handle if things go wrong.
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[*] posted on 16-4-2019 at 23:22


Industry detonators are thin Al tubes. With a steel sleeve surrounding the primary. Ideally. Very thin tubes are wanted as we want energy going into the explosive not accelerating the case/tube. But for DDT strong tubes are usually needed. However I have had success in a carbon fiber arrow tube. But the ddt formula for that is complex.
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FeedMe94
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[*] posted on 17-4-2019 at 00:49


I made a small detonator with 300mg recrystalized ETN slightly press inside a plastic 2ml tube. The rest was filled with al foil and ignited by visco fuse. It sounded like it detonated but im not sure if it went full order.

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