253 replies to this topic

[Richard H]

You would find that there is a point beyond which there is little advantage to further milling.

[EnigmaticBiker]

Just out of curiosity, did any of you ever consider milling their BP for an insanely long amount of time? Say, 100 days or something. And how fast would the BP be when it's done?

No, just building a mill at the moment.

I guess that the BP would be fast but imagine that it would reach a certain level of mixing/particle size early on and probably not change much after.

The point at which it becomes homogenous could be found by sampling at set intervals, checking the speed and drawing a graph.
I'd like to see a graph of that, someone has almost certainly done it already.

Simon

[Nerro]

The thing is I'm just really curious what the utmost burning rate of BP could be. So with the best materials and a hugely long milling time to ensure perfection.

[paul]

Read something about 60 hours of milling as a maximum. After that time speed of combustion won?t improve anymore.

Just what I read in rec.pyrotechnics IIRC.

[Andrew]

I was thinking, I don't know if this has been suggested before, but does anyone else thing that the following is a good idea?

A bit of very accurate standardised kit gets sent round all the people that want to join the quest for the fastest BP. When one person has finished with the burn rate tester, they say so and the next address gets sent to them. The next person gets it and so on; a bit of a chain competition if you will. There would obviously be rules and the tests would be standardised. Each individual person?s method of manufacture would be carefully documented with a standard form downloadable from somewhere to fill in. It would lead to a bit of armature research on mass. Everyone would enter their test results and a bit of a league table could be done. Obviously the amount of BP you would need to fill the device would be less than 100g to make sure no one gets buggered by MSER and cannot enter. Each person would be responsible for shipping it to the next, and so on, la de la la. Perhaps a bit of a competition incentive could be thrown in. To ensure no cheating occurs, well that?s complicated and I cannot think of everything!!

Any thoughts???

Would anyone enter? PM me if you would be interested, if enough people are I would not mind organising it.

Is anyone interested???

On the milling for ages topic. I have found that milling for more than 3 hours actually slows the burn rate of your milled powder, grain is a different story of course.

[fishy1]

Is anyone interested???

On the milling for ages topic. I have found that milling for more than 3 hours actually slows the burn rate of your milled powder, grain is a different story of course.

if it gets slower after you keep on milling it, i think their's something amiss.

[EnigmaticBiker]

Is anyone interested???

On the milling for ages topic. I have found that milling for more than 3 hours actually slows the burn rate of your milled powder, grain is a different story of course.

I'm interested, but am in the process of building equipment so couldn't compete.

Curious about your last comment, do you have any theory as to why the burn rate would slow?

Simon

[Frozentech]

I'm interested, but am in the process of building equipment so couldn't compete.

Curious about your last comment, do you have any theory as to why the burn rate would slow?

Simon

I've pretty much settled on 3 hours of milling ( in my particular mill, with my usual media) as being about optimum also. I think the reason over-milling actually slows down the burn rate of meal powder is that there is not as much space between the grains for the flame front to propogate, the grains are more 'packed' together.

I imagine that using pressed and corned BP, it might get faster with longer milling since burn rate will depend on grain size in the corning process, 'combustion chamber' pressure, etc.

[EnigmaticBiker]

I've pretty much settled on 3 hours of milling ( in my particular mill, with my usual media) as being about optimum also. I think the reason over-milling actually slows down the burn rate of meal powder is that there is not as much space between the grains for the flame front to propogate, the grains are more 'packed' together.

I imagine that using pressed and corned BP, it might get faster with longer milling since burn rate will depend on grain size in the corning process, 'combustion chamber' pressure, etc.

Ah, of course, I think I remember now, something like...
The distance the flame front can propagate will apply on the scale of powder, in a similar way to the much larger grain. But when corned, the greater milling time gives a better mixture and the grain size takes care of the flame propagation speed.

I guess the milling limit might change slightly if harder and heavier media used.
I the recent TV programme about the gunpowder plot, a reconstruction was done and the spanish mills producing the gunpowder for that, put huge energy into it.
Sounded less like tumbling and more like beating it to death .

Simon

[Andrew]

I am just guessing that there is less air and thus less space for a flame to propagete through in an unltra fine powder; a true fluid powder will only end burn where as a powder than has courser particles will burn through as well as on the end. Thats a guess btw, probably holds some truth!

Don't worry this is not based on ponderings, but actual observations. I would like to do a study into burnrate/milltime etc one day, the competition I suggested is partly to achieve this.

[EnigmaticBiker]

I am just guessing that there is less air and thus less space for a flame to propagete through in an unltra fine powder; a true fluid powder will only end burn where as a powder than has courser particles will burn through as well as on the end. Thats a guess btw, probably holds some truth!

Don't worry this is not based on ponderings, but actual observations. I would like to do a study into burnrate/milltime etc one day, the competition I suggested is partly to achieve this.

Basically in coarse grain, at any one moment in time, more of the BP is burning than in a block or fluid powder.

[fishy1]

hehe, whipped up 8g of sulphurless balsa BP, just put it through a sive a few times, didn't mill it.
the 8g had a volume of about 1/2 a pint, and burnt incredably fast! a line of it was gone faster than i could see, and burning 2g in a pile dazzled me from 10m away.

very nice, especially if you don't have a ball mill but need to make something fast.

only bad thing is, balsa wood is expensive as hell.

[EnigmaticBiker]

hehe, whipped up 8g of sulphurless balsa BP, just put it through a sive a few times, didn't mill it.
the 8g had a volume of about 1/2 a pint, and burnt incredably fast! a line of it was gone faster than i could see, and burning 2g in a pile dazzled me from 10m away.

very nice, especially if you don't have a ball mill but need to make something fast.

only bad thing is, balsa wood is expensive as hell.

Yay! That's pretty fast, haven't tried balsa yet, but will when I find a cheap or free supply.

I've always used sulphur with KNO3, which do you find faster, with or without?

Simon

[fishy1]

Yay! That's pretty fast, haven't tried balsa yet, but will when I find a cheap or free supply.

I've always used sulphur with KNO3, which do you find faster, with or without?

Simon

normally faster and easier to light with sulphur, but this balsa wood was so quick i made it without sulphur.

[completebeginner]

I just tested some pine bp and have found it to be quite slow in comparison to alder bp but if you are going to make alder bp use 70 20 10 proportions