Kn03 not milling fine.. Still coarse

[giod]

My kn03 has been in the ball mill with 50% .5" lead media for two days, and it's no finer than it was after 3 hours. Twice now my kn03 only grinds to rough powder, it's still palpable on the finger tips.. Using it for flash, smoke generators, and rocket fuel. It's fine dust, but I can still feel it when smashed between my fingers..

Questions :

Is this normal?

Does it matter?

[PyroCube]

This is definitely not normal. How fast does your ballmill spin, what are the dimensions of your milling container?

 

 

greets

[giod]

It's a chicago brand double mill 5" diameter/ 5" canister.. 65 rpm.

Again powder is fine, but no where near 10 micron. Maybe 100 micron?

Maybe that's as fine as it gets?? Fine, but. Not as fine as powder AL or powdered sugar.. Trying o get it to the same sons instance as powdered sugar for good integration for rocket fuel and/ or flash.

[bob]

One thing I find when milling kno3 in a ball mill, particularly when using a small mill, was that if I left it for say 1 hour, half of it would be a decent mesh size, and the other half wouldn't have changed at all. Then if I left the kno3 in the mill for 4 hours, there wouldn't be any powder just larger chunks than what I first started out with. Yes the kno3 should get much finer then what your describing. How much media do you have in the jar? Yeah I know you said 50% but I'm not sure if you mean that the jar is half full of media or if you are referring to something else. Have you tried using a blender to grind it? Maybe I shouldn't say this but if your having trouble grinding KNO3 then I don't think you are ready for flash powder.

[TYRONEEZEKIEL]

Try this to help your mill work better. You should be able to make your KNO3 finer than powdered sugar.

 

This is taken from Sponenburgh's book.

 

You want to fill your jar 50% empty volume with grinding media. Then charge it with 25% empty volume of KNO3.

 

The optimal RPM for your jar is 65% of the critical speed. The critical speed is the point where the media will begin to stick to the wall from Centrifugal force. Here is how the critical speed of your mill is determined.

 

Critical Speed= 265.45

Sqrt(Jar ID - Media OD)

 

So in your case.

Critical speed = 265.45

sqrt(5-0.5)

Your critical speed is 125.134 rpm. That being said. Optimally your jar will rotate at 65% of that.

 

Your jar needs to spin at 81 rpm.

Edited August 16, 2013 by TYRONEEZEKIEL

[giod]

Will try to increase mill speed. Yes I charge the canister with 50 percent lead media and 25 percent kn03. Again, it gets fine enough to cake, but still feels slightly gritty.. I guess I want to get it like 20 micron, but never seems to get there even after days. It's hard to explain, it's fine, but I can still feel very fine grit when rubbed between my fingers.. I switched to kcl04 for flash, no need to mill, works perfect at 70/30 right out the bag. The kn03 seems to work fine for my BP comps. Edited August 18, 2013 by giod

[Mumbles]

You might want to try to dry everything out next time. I had the same problem you're having. My KNO3 would never grind to a completely fine mass. I'm relatively confident that this was due to the KNO3 caking. The fine powder would cake around the bigger particles, and prevent them from being totally ground. What generally worked to fix this was to pre-grind my nitrate, and then to dry it in an oven to expel moisture. You might also try to dry your jar and media. I've seen some people also cook their media and jars, but I was never this brave. What I did was to add a packet of strong desicant to my sealed jar for 24hr, and do a couple rounds of this. Drying my nitrate largely fixed the issue on it's own however.

 

You mentioned anti-cakes in another thread. That might also be worth a shot. If I was milling with something to lubricate the nitrate, like charcoal, I never had any caking or grinding issues. As mentioned though, adding anti-cake has caused some binding issues for some.

 

I feel like I have to say this. You seem to have a good interest in pyro, and look to understand it, but also have sort of an uncomfortable fascination with flash powder. I urge you to stay away from it until you get more experience. The issues you've been having, while common, are also fairly simple issues that an experienced person would easily fix.

[giod]

You might want to try to dry everything out next time. I had the same problem you're having. My KNO3 would never grind to a completely fine mass. I'm relatively confident that this was due to the KNO3 caking. The fine powder would cake around the bigger particles, and prevent them from being totally ground. What generally worked to fix this was to pre-grind my nitrate, and then to dry it in an oven to expel moisture. You might also try to dry your jar and media. I've seen some people also cook their media and jars, but I was never this brave. What I did was to add a packet of strong desicant to my sealed jar for 24hr, and do a couple rounds of this. Drying my nitrate largely fixed the issue on it's own however.

 

You mentioned anti-cakes in another thread. That might also be worth a shot. If I was milling with something to lubricate the nitrate, like charcoal, I never had any caking or grinding issues. As mentioned though, adding anti-cake has caused some binding issues for some.

 

I feel like I have to say this. You seem to have a good interest in pyro, and look to understand it, but also have sort of an uncomfortable fascination with flash powder. I urge you to stay away from it until you get more experience. The issues you've been having, while common, are also fairly simple issues that an experienced person would easily fix.

 

Yeah, when I make my BP it seems to get dust fine at the end of it all.. Maybe the charcoal helps it .. It def cakes ALOT when milling alone. I'm gonna try the cab o sil next time I mill some kn03 . I have decident in the storage jar. Will try pregrinding it in the magic bullet next time also. The cakes seem "moist" but not. Will advise next run. Glad to know someone else had the same prob. Re the FP, yeah not gonna lie, it was the second thing I made, although I spent two weeks researching how to do it safely (as safe as can be) before I made it. Found that kcl04 and 5 micron bright or Elkhart work perfect 70/30. Everyone like things that go bang right? Def treat it with respect always diapering, and never more than 10g at a time.. Great for salutes. Working on my first mortars now.. No FP needed, until I get to salute shells. Today I made my first star roller, and first batch of BPCR. Got granulated BP down. Next step stars and shells.

[TYRONEEZEKIEL]

Giod. You certainly will need flash powder for small shells or at least a similarly powerful booster. (H3, whistle, Nitrate flash). It's not a bad thing. Flash is a very useful and valuable comp in pyro, but it just commands respect. This is simply because it is some very nasty stuff when used in an unsafe manner. I know from experience. When I first started in pyro I made "flash powder" by shaving a magnesium block with a knife, and grinding some stump remover in a mortar and pestle. I would combine the flakes and granules and lit it with a flint and knife. (Very. Very, Very poor decision on my end, but I just didnt know better at the time). The comp would just smolder and then flash similar to a strobe. So I thought thats what flash powder was. Shortly after, I got my hands on very fine stuff. I lit a half gram of it with the same manner. It instantly roasted all the skin off my pointer finger. It was pretty nasty. Luckily for me it was a small batch of slow flash. Now imagine if I would have done that with 70:30 dark perc flash.

 

Thankfully I am perfectly healed and have no scars from it, but it did teach me the power of flash and what it actually is capable of. All this being said, just treat it with respect. Big booms are fun to make from time to time, but they are just like candy. If you eat too much of it you will get sick. The real steak and potatoes comes with the infinite assortment of neat pyro devices that shoot out colors and showers of sparks. You will see exactly what I am talking about

[giod]

Giod. You certainly will need flash powder for small shells or at least a similarly powerful booster. (H3, whistle, Nitrate flash). It's not a bad thing. Flash is a very useful and valuable comp in pyro, but it just commands respect. This is simply because it is some very nasty stuff when used in an unsafe manner. I know from experience. When I first started in pyro I made "flash powder" by shaving a magnesium block with a knife, and grinding some stump remover in a mortar and pestle. I would combine the flakes and granules and lit it with a flint and knife. (Very. Very, Very poor decision on my end, but I just didnt know better at the time). The comp would just smolder and then flash similar to a strobe. So I thought thats what flash powder was. Shortly after, I got my hands on very fine stuff. I lit a half gram of it with the same manner. It instantly roasted all the skin off my pointer finger. It was pretty nasty. Luckily for me it was a small batch of slow flash. Now imagine if I would have done that with 70:30 dark perc flash.

 

Thankfully I am perfectly healed and have no scars from it, but it did teach me the power of flash and what it actually is capable of. All this being said, just treat it with respect. Big booms are fun to make from time to time, but they are just like candy. If you eat too much of it you will get sick. The real steak and potatoes comes with the infinite assortment of neat pyro devices that shoot out colors and showers of sparks. You will see exactly what I am talking about

 

Yeah, thanks for that, I'm def respectful of the flash. I Made 1, 2, and 3 gram salutes. It amazes me how freaking loud just a gram of dark perc fp can be, in just a tiny plastic cap. I was using wire nuts with 1 gram in them with a fuse threaded in first, then hot glue for sealer. Omg so loud, just 1 gram. Yeah the stuff scares me. I get nervous putting hot glue on top of it even on the low setting.. I just made my first star roller, so I'm on to that now... Question about small shells. Gonna start with 2" canister shells, will mcrh work for burst, or do I need fp boost. Or should I use just straight meal powder?

 

[TYRONEEZEKIEL]

You are definitely making great strides in the right direction. As for breaking 2" canister shells I broke mine with a flash bag. NightHawkInLight has a very good tutorial on youtube showing this method beautifully. I took a 2" square of wax paper and wrapped it over my thumb, creating a little cup. I poured 1.5g flash in, then placed my visco time fuse in. Then I took a very small zip tie and zipped it around the set up. I finished it off with just a dab of hot glue around the fuse so the flash wouldnt fall out.

 

This method is absolutley perfect for breaking such a small shell. However if you are looking for a more traditional break method, then you can use pulverone with just a touch of flash for boost. For my case, since I was still so new at star making/shell building/BP manufacture that I didnt even want to mess with a BP based break.

[giod]

You are definitely making great strides in the right direction. As for breaking 2" canister shells I broke mine with a flash bag. NightHawkInLight has a very good tutorial on youtube showing this method beautifully. I took a 2" square of wax paper and wrapped it over my thumb, creating a little cup. I poured 1.5g flash in, then placed my visco time fuse in. Then I took a very small zip tie and zipped it around the set up. I finished it off with just a dab of hot glue around the fuse so the flash wouldnt fall out.

 

This method is absolutley perfect for breaking such a small shell. However if you are looking for a more traditional break method, then you can use pulverone with just a touch of flash for boost. For my case, since I was still so new at star making/shell building/BP manufacture that I didnt even want to mess with a BP based break.

 

So with the little FP bag, what else filled your canister? Just stars? I just finished my first 2 inch canister shell from scratch, spiked and all! My lift powder and meal powder are great I got it down I think. What visco do you use for time fuse? What mm size/ rate of burn. Do you prime it? How? Can not wait to soot my first shell, but it's too dry here, and too much fire hazard. Have to wait.. Grrr.

[TYRONEEZEKIEL]

I am in a burn ban where I live and have not had stars light the grass on fire. I do keep 2 extinguishers handy when I shoot though just in case. I just filled the rest of the shell packed with cut stars. Rolled stars dont work as well in canister shells, but it may not matter as much on a small guy like that. I used the regular ol' green visco you can buy at the fireworks stand. I think its 1/8" and burns at around 1.5s/inch. I bought mine from pyrodirect as waterproof green visco. Make sure it isnt fast fuse. Visco really likes to take fire, but what I did was snip the end in half with some small wire cutters and dip it in some good ol' Vitamin F. I suppose you could dip in in NC laquer then into some 3F BP if you are paranoid, but in my case visco really likes to take fire.

 

I would recommend wrapping the whole visco time fuse in a single turn of masking tape just to make sure it wont take fire from the sides.

 

You really cant go wrong with these kinds of shells. They are pretty forgiving, and with the nature of canister shells, symmetric bursts aren't really a concern. I really think it is the best way to learn how a shell works and how to build one.

 

Good job spiking. That is crucial to can shells.

[giod]

. Visco really likes to take fire, but what I did was snip the end in half with some small wire cutters and dip it in some good ol' Vitamin F. I suppose you could dip in in NC laquer then into some 3F BP if you are paranoid, but in my case visco really likes to take fire.

 

I would recommend wrapping the whole visco time fuse in a single turn of masking tape just to make sure it wont take fire from the sides.

 

 

Vitamin F for flash? Do you moisten the Cisco with something to get it to stick? Also the tape wrapped visco, do you tape the part in the lift bag/cup, or the part inside the canister, or both? On my second shell I ran visco through the side of the lift cup, and straight on into the canister, one continuous piece, so that it would work dual purpose, ingnite the lift powder and keep burning through tomthe core of the canister, I can see why we would wrap the part inside the lift cup so that it keeps burning and doesn't have a secondary ignition further down the fuse. Gonna be hard to time I guess though..

[Mumbles]

I gave up using visco as a time fuse a long time ago. You might want to look into spolettes. They're easy to make, and very reliable.

 

Back when I was using it, lightly moistening the end of the fuse with water or something and dipping it into finely granulated meal did the trick for me. I wouldn't suggest using any sort of moistening agent that isn't going to evaporate or burn. Typically I taped the section I wanted to have a delay. 1" of tape would correspond with about 3 seconds of delay. I left some exposed visco on both ends to prime and give better fire transfer.

[giod]

I gave up using visco as a time fuse a long time ago. You might want to look into spolettes. They're easy to make, and very reliable.

 

Back when I was using it, lightly moistening the end of the fuse with water or something and dipping it into finely granulated meal did the trick for me. I wouldn't suggest using any sort of moistening agent that isn't going to evaporate or burn. Typically I taped the section I wanted to have a delay. 1" of tape would correspond with about 3 seconds of delay. I left some exposed visco on both ends to prime and give better fire transfer.

 

yeah I can see that if I ever want to make a reliable well timed shell, I should just use the timed fuse.. to many different visco fuse times anyway. Spolettes seem to me like a cool and traditional, yet somewhat antiquated way of timing a fuse, I mean not hard to make, but isn't it just far easier to by already timed fuse ? I'm not a purest at heart, I don't feel the need to make everything from scratch.. its like rolling your own salute tubes, it can be done.. or making your own hemis, it can be done, but when you can buy them sooo cheap, i'd think your time is worth more than the few pennies you save doing it your self, plus lets face it, the reliability of timed fuse over timing your own spolletes.. not likely your timed spollete will be more accurate than timed use..

[Mumbles]

I will agree in part with you. Buying time fuse is certainly easier, and probably a little faster than making your own spolettes. However, when given a choice between spolettes and trying to adapt visco into a time fuse, spolettes are less troublesome and probably faster. Spolettes are however significantly more reliable and more accurate than timefuse. To even approach the accuracy of spolettes, special jigs and tools need to be made, and additional techniques are employed.

 

Thats part of why we do this though. If you think your time is even worth pennies, it's far cheaper, easier, and faster just to buy fireworks.