Sciencemadness Discussion Board - Detonator casings

Detonator casings

nux vomica - 16-3-2016 at 03:19

Here's a neat find, if you open up 9 volt alkaline batterys the cells are 8 mm diameter and long enough to load the equivalent of a no8 detonator.
The caseing is very thin nickel maybe stainless steel but its the closest ive seen to a off the shelf caseing .
Nux

NeonPulse - 16-3-2016 at 04:18

Try these! That is if you are willing to risk importing them. I know that I'm not. But if you live in Europe or a country fairly lax then there should be no problems.

http://pyrofire.eu/detail.php?product=114#.VPqPj2SUde8

greenlight - 16-3-2016 at 10:27

@nux, is one end of those cells inside the battery sealed or are they open ended once you remove the contents? I can't see on the pictures

Loptr - 16-3-2016 at 10:48

I wouldn't be afraid to import those. They are used for making sensors and used as the housing. You could also contract out their manufacture as there are several companies in a Google search that will produce closed end tubes.

hissingnoise - 16-3-2016 at 10:53

NP's aluminium tubes look like the right stuff, but Pyrofire's shipping seems a bit rip-off!

Has anyone here had any dealings with them, I wonder?

Bert - 16-3-2016 at 11:36

Looking at their prices for Chinese shells, fuses, quick match, pyrotechnic chemicals & etc., they are a bit high. Oddly, the electric match prices were sort of OK (.5€) Didn't check shipping costs, as not ordering!

The picture does not show if the output end of the empty capsule is properly concave.

Hennig Brand - 16-3-2016 at 13:01

An experimenter could probably easily make a little punch and anvil set for making/shaping a suitable dimple/concaved end in the tubes if needed.

Herr Haber - 16-3-2016 at 13:59

Quote: Originally posted by NeonPulse

Try these! That is if you are willing to risk importing them. I know that I'm not. But if you live in Europe or a country fairly lax then there should be no problems.

http://pyrofire.eu/detail.php?product=114#.VPqPj2SUde8

I get mine from there. Very happy with these tubes. I'll post pictures of tests I made with them some day. I've got some copper ones that I'll try with something else than LA of course.
I get my fuse from them too. Their Visco is excellent and their Bickford fuse just need a roll of tape to make them a perfect fit for the tubes before crimping. Nice people, we exchanged a couple e-mails at a time.

The specifications are wrong though:
Outer: a tad more than 5mm
Inner: a tad less than 5mm
Lenght: 56mm
(Sorry, my "whatever you call this in English" isnt digital

They also have shorter tubes with a bigger diameter that I havent found a use for. I got some to see if they gave me ideas.
Outer: a tad less than 7mm
Inner: 6mm
Lenght: 36mm

Also, note that the way these tubes are made the walls are thicker at the bottom than at the mouth.

Herr Haber - 16-3-2016 at 14:09

Quote: Originally posted by Hennig Brand

An experimenter could probably easily make a little punch and anvil set for making/shaping a suitable dimple/concaved end in the tubes if needed.

An experimenter could. The bottoms are flat and as mentioned above, slightly thicker than the walls of the tubes.
The bottoms are marked (not deeply) with an "A" for Aluminium I guess.
Also, it seems to me that they are not perfect tubes. The open end is ever so slightly larger than the closed end.
I couldnt give data, but I noticed differences in behaviours when working with these tubes and different loads. One of my tools would get stuck with lesser loads.
Ah, maybe that's something I should explain if or rather when I create a topic about my experimentations.

@Bert: I belive they use these tubes, fill them with black powder and crimp whatever they need on top. I've gotten some other supplies from them (no, not chemicals they're way to expensive) but their finished products are sometimes very nice for the price.
I have a couple of pyrotechnic igniters from them where the bottom is deeply marked with an X to ensure it breaks there. They are the same that they use for some smoke bombs.
I guess they are selling the tubes alone because... well maybe they thought someone might want to use these tubes to house a sensor for example. Or other

[Edited on 16-3-2016 by Herr Haber]

nux vomica - 16-3-2016 at 21:27

Quote: Originally posted by greenlight

@nux, is one end of those cells inside the battery sealed or are they open ended once you remove the contents? I can't see on the pictures

Yep Greenlight you cut the crimped end off and its a deep cup .

Added a cople of other photos with some more dimensions including sidewall and bottom thickness

[Edited on 17-3-2016 by nux vomica]

greenlight - 17-3-2016 at 09:34

Thanks Nux, nice find there. I have been using aluminum tubing from a hobby shop but the bottom's has to be sealed before filling them

DrManhattan - 3-3-2018 at 20:17

I have thought of the idea of using an ETN/epoxy mixture for making a putty to seal the end of open tubes for use as a blasting cap. Once dried it should be reasonably strong, water tight, and unlike an inert plug it shouldnt decrease its initiation ability so long as it detonates from the pressed ETN charge above it. What do you guys think?

Laboratory of Liptakov - 4-3-2018 at 02:45

Your plug in output segment is too much thick. Without description of thickness. Here is more safety construction:

Daffodile - 4-3-2018 at 12:57

How would you crimp them?

Bert - 4-3-2018 at 13:25

Traditionally, a fuse cutting and crimping tool.

Occasionally, I have used a small tubing cutter with a deliberately dulled cutting wheel, this gives a very uniform crimp. But requires having my hands WAY too close to the cap.

50163651lg.jpg - 22kB

MineMan - 4-3-2018 at 20:46

Bert,

You have WAY too much cool stuff and antiques, those would fetch a lot of $.

Ok Time for safety talk. LOL, steel casings of that thickness should NOT be used for detonators, the shrapnel form that would be inconceivable. Steel wire gloves under steel wire gloves or Kevlar was shown to greatly reduce injury by Robert Matyas... but I have tried this, dexterity is sacrificed.

The most ideal detonator casing is thin (.05mm or less Al), lets talk about why. I have seen FLAKES of copper from a copper detonator casing pierce a 5 gallon bucket, these flakes would NOT register on a milligram scale. Copper is the worst material, because it is elastic, therefore the casing will bend before ultimate failure, producing the HIGHEST Gurney velocity... In addition, at high velocities penetration is modeled by two main variables, the density of the projectile, and the density of the target. The hardness does not matter at velocities over 1km/s. Therefore, copper is the worst material for shrapnel, tantalum, probably being the most violent material imaginable... and hence is used for advanced shape charges. Steel is brittle, but at a 2mm thickness, the fragments must be ungodly. DDT of CHP is still possible under .5mm aluminum, and should be used. your hand might miss some fingers but you wont have holes out your backside, and yes, I have seen copper FLAKES pierce 1mm steel after going through tough plastic. According to Matyas, even one pair of steel wire gloves helps a lot,same with kevlar or spectra. it will at the very least protect your flesh and hold bones and fingers together.

A cap like the above shown could really easily kill, not just mame. If the material cannot achieve ddt in .5mm Al, then a steel sleeve should be used, as it is in industry caps, but thick enough where it only deforms, not fragments. it only needs to cover 100mg of the material until it ddts...

No picture online shows a modern cap. But there is a thick sleeve that covers the LA, it helps if a truck runs over it, and it can help with our members too.

Fulmen - 5-3-2018 at 03:38

Bert: I have the same unit. Still works :-)

C6(NO2)5CH2CH(CH3)N(NO2)2 - 21-3-2019 at 13:42

I've opened up a 9v battery. Those are nicely shaped and sized casings. But the battery I opened had a very very hard graphite/Manganese oxide layer up against the casing wall. It could be removed in chips, but not removed completely without destroying the steel casing. Are there any special tips for getting rid of that layer, or should I just be more perseverent with the flat-tip screwdriver?

XeonTheMGPony - 22-3-2019 at 04:24

https://www.aliexpress.com/item/5-pieces-OD-6mm-OD-7mm-OD-8m...

If you know spechs, there are many possibilities

OneEyedPyro - 25-3-2019 at 06:41

Quote: Originally posted by C6(NO2)5CH2CH(CH3)N(NO2)2

I've opened up a 9v battery. Those are nicely shaped and sized casings. But the battery I opened had a very very hard graphite/Manganese oxide layer up against the casing wall. It could be removed in chips, but not removed completely without destroying the steel casing. Are there any special tips for getting rid of that layer, or should I just be more perseverent with the flat-tip screwdriver?

Submersion in dilute hydrogen peroxide should clean them up nicely if it's MnO2 inside.
Peroxide would likely begin to corrode the casings pretty quickly though.

ManyInterests - 19-10-2021 at 23:36

While I still haven't made my primary or secondary yet. I have been thinking very hard about the detonator design, because without that, there is no point in bothering to try making energetics.

While I've seen people speak very highly of aluminum tubes, I've also seen that cardboard or rolled printer paper can be used as a detonator housing. But I've also been looking at using the body of a ballpoint pen as a house. I've attached a blurry pic of what I plan on using.

The pen's inner diameter is apparently 6.5mm or so, because I fit a 6.35 mm wooden dowel in easily. When I removed the cap and the actual pen head/handle the result was a very nice plastic tube. I wanted it to be a little longer. So I cut off the head of the cap and sealed the end with hot glue, then I used more hot glue to completely seal the cap to the body (I put some near the edge of one side and pressed the head against it, bringing hot glue underneath it. The connection is very tight).

I made a paper funnel that will let me attach a glass lab funnel to that end, allowing me to pour the energetics into it easily (albeit I will need to tape them together to make a firm connection). I filled it with 2 grams worth of sugar just to see if it'll fit that much, and it left plenty of space for me to insert an electric match and seal the other end with epoxy.

Would this work as a detonator?

macckone - 20-10-2021 at 08:52

I like christmas tree lights.
And now is the season to get them.

They come with wire preinstalled.
fill and drain thin nitrocellulose syrup to coat.
Then primary and ETN.

Seal with thick nitrocellulose syrup.

Side note, the metal cans in 9v are usually zinc.
Same as other batteries.

Using a smaller christmas light initiator with a can filled with ETN would make an excellent larger initiator.

ManyInterests - 20-10-2021 at 11:45

Quote: Originally posted by macckone

I like christmas tree lights.
And now is the season to get them.

They come with wire preinstalled.
fill and drain thin nitrocellulose syrup to coat.
Then primary and ETN.

Seal with thick nitrocellulose syrup.

Side note, the metal cans in 9v are usually zinc.
Same as other batteries.

Using a smaller christmas light initiator with a can filled with ETN would make an excellent larger initiator.

I got halloween lights (which come in orange and purple) and clear christmas lights. They are good, but with many small and long caps (like mine) you will need to remove the bulb entirely in order to make it fit. This isn't a problem. I'm very good at cutting the tops off and filling them with pyrogen (I used crushed match heads).

The only thing you need to know is that christmas light bulbs are polarized, meaning one wire is positive while the other is the ground. If you are working with colored christmas lights, make sure you use the correctly corrected wires so you can connect them to the power supply correctly, otherwise they might not ignite correctly.

If they are clear and you see the filament on the inside, the longer part is the positive while the shorter one is negative, makes it easier to get the wires properly connected.

But if you completely remove the bulb from the container and attach the wires directly to the leg wires you do need take care that they don't touch and create a short, this might cause your bulb not to light up when it needs to.

Personally I perfer my own matches. They are quite current and voltage sensitive (much more so than christmas lights) but I do have experience building them and I did make sure what ever I have in mind will fit in my intended cap.

But that being said. If it works, it works.

My question still remains on making the setup to do the filling and pressing (the pressing is what worries me the most. Which is why I want to use only the most insensitive explosives out there for that purpose. ETN as the secondary and NHN as the primary (with fast black powder as the initiator).

but I am thinking about something. Is picric acid less sensitive than ETN? What about it's compatibility with NHN? I know picric acid hates all metals except aluminum, but would it eat through my plastic pen body and the hot glue stopper I have at the end?

I am thinking a simple homemade hydraulic press like this might suffice:

https://www.youtube.com/watch?v=aWVqmgX-VrY

I know it looks all childish, but aslong as it lets me operate the pressing from afar (and keep the cap in a container that will contain the blast and muffle the sound) I am OK with it.

[Edited on 20-10-2021 by ManyInterests]

macckone - 21-10-2021 at 13:31

That is an interesting hydraulic press.
I have been using a pretty sturdy metal press and a lever (pvc pipe) that allows me some distance.
But that could literally work from 100 ft away.

You need cheaper christmas lights, mine just use miniature light bulbs that run on 3v.
Hook 18v (two nine volts) to one and it vaporizes the filament pretty good.
The way the filament is oriented one side is longer than the other but it isn't 'polarized' in the sense that an LED is.

ManyInterests - 21-10-2021 at 15:55

Quote:

You need cheaper christmas lights, mine just use miniature light bulbs that run on 3v.
Hook 18v (two nine volts) to one and it vaporizes the filament pretty good.
The way the filament is oriented one side is longer than the other but it isn't 'polarized' in the sense that an LED is.

I think we're using the same incandescent mini-bulbs. I got them from a thrift store. They have an 'outdoor' mini-bulb that is rated for 3.5 volts each and an 'indoor' one for 2.5 or 3 volts. LED lights are useless for pyrotechnics.

I did make one into an electric match and it did light up with a small CR2032 button cell, but a 9v is necessary to really get to light up. Albeit you must not forget that the filament will still burnout once you break the bulb. They tend to not like the open air that much.

For my purposes even 2 9v batteries connected in series will not be enough. 9v are good if you're working close to the thing. But if the wires are very long (and I cut some LONG wires) you'll not only need a strong voltage, but also a stronger current. connecting 6 or 8 D cell batteries in series will give you 9 or 12 volts respectively, but the current provided by the D cell will crush anything a 9v can do.

Brightthermite - 21-10-2021 at 16:50

You should all do yourself a favor and go out and get a 12v lead acid lantern battery from Home Depot or Lowes and you wont go back to regular cell batteries.

ManyInterests - 21-10-2021 at 17:27

That's too much. 8 D-cell or even C-cell is plenty for my purposes. I made an electric match using 2 3-meter long wires to my RF module for a test and it light up nearly instantaneously. I did this with C-cells (D-cells are even more powerful). I cannot ask for more. I plan on putting my RF module in a box to shield it from any debris while I will be as far away as I can, but still within line of sight

Speaking of which I wish to showcase my expertly created hydraulic press!

macckone - 22-10-2021 at 08:24

2 x 9v will provide 5 watts with alkaline cells, maybe more if you use lithium. You get some voltage drop but it is going to max out in that range.

Considering the light bulb is rated at half a watt, that is more than sufficient.

If you are doing a string of igniters, you may want a higher voltage and amperage potential. D cells are totally overkill. AA are plenty for this type of igniter system and 9v cells are sufficient. Assuming a single igniter. 6v is sufficient to cause the bulbs to burn out.

Professional systems charge a capacitor up to 100v then release the charge with the button push. But they are designed for a string of explosives. They also have safeties and such that are probably going to be lacking in a non-certified system.

Estes rocket launch controllers put out either 6 or 9v depending on the model. The 9v model uses C cells.

MineMan - 23-10-2021 at 23:15

Quote: Originally posted by ManyInterests

That's too much. 8 D-cell or even C-cell is plenty for my purposes. I made an electric match using 2 3-meter long wires to my RF module for a test and it light up nearly instantaneously. I did this with C-cells (D-cells are even more powerful). I cannot ask for more. I plan on putting my RF module in a box to shield it from any debris while I will be as far away as I can, but still within line of sight

Speaking of which I wish to showcase my expertly created hydraulic press!

I don’t see that working. There will be a force on the cardboard bridge.

NHN and ETN are pretty stable stuff. Imho, you can do it by hand. Minimum amount is a beauty. Your making this way to complicated, unless you enjoy the process.

ManyInterests - 24-10-2021 at 14:14

Quote:

I've tested dozens of e-matches and will likely do more tests before the whole thing. Outright Failures are quite rare with my matches. The one thing you need to remember about ultra-thin nichrome wire vs 'just' thin nichrome wire is that it the 0.08mm and 0.1mm like to jump around, this means getting them to make continuous contact with the match head is tricky. I might end up having to use some of my 0.25 nichrome wire because it isn't as springy. I did manage to find a way to light up a match with 0.25mm nichrome wire using 2 AA batteries (alkalines. Steer clear of the carbon-zinc stuff for this purpose!) But if the wires are very long you will need more than just the 3 volts afforded by the 2 AA. 8 AA batteries worked, but I'll use the C cells because I want to guarantee they'll work.

To make sure that the wire touches the matchhead with 0.08mm or 0.1mm I've wrapped a bit of the wire around the head. This does create a short, but in this case it is actually what you want because shorts in a nichrome wire do cause it to get white-hot very quickly

And yes, for me it's ALL about the process!

katyushaslab - 25-10-2021 at 02:18

For your batteries, skip the shite alkaline cell ones and just buy a LiPo pack + charger with a high discharge rating (high "C" value) from any hobby/RC store online or locally. Usually I go for ones around the 11-13V range for lighting electric matches. They will instantly heat up even the thicker nichrome at the end of a long wire.

Another good option is the portable jumpstart boxes for cars, but those are heavier.

You seriously do not want to under-power your initiation setup, nothing is worse/more likely to kill you (or someone else) than a device failing or going into an unknown state because you cheaped out on the initiation setup. You can't just leave it there and fuck off, you have to deal with it.

Laboratory of Liptakov - 26-10-2021 at 08:41

Today's Li-Po's discharge current is even 80 times higher than the value written on the cells. So 1000 mAh will supply an instantaneous current of 80 A. 1800 mAh will immediately supply 144 A. Therefore, it is necessary to focus on a quality switch (relay). Which can withstand a surge.

ManyInterests - 9-11-2021 at 19:45

Absolutely Li-Po batteries are the best for this sort of thing. But they're very expensive and I don't have any (unless you count the power bank I have for my phone).

Quote:

You seriously do not want to under-power your initiation setup, nothing is worse/more likely to kill you (or someone else) than a device failing or going into an unknown state because you cheaped out on the initiation setup. You can't just leave it there and fuck off, you have to deal with it.

Absolutely. This is why I've done more testing regarding this than anything else. I am very confident in current setup. I've already several test caps using black powder, nitrocellulose, and sugar-chlorate mixtures and none have failed to go pop. I tested them with lower power battery packs. The one I will be taking with me on my final test will be substantially more powerful.

Again this is not to say I don't think that Li-Po battery packs aren't good. They are the best, but my current setup is already above and beyond.