65 replies to this topic

[pyrosailor99]

Hi all!

i recently built my BallMill.

i've just finished milling my first batch.
i milled 3kg batch for 30mins. then as i understood 3kg was toomuch for the jar, i reduced it to about 2,3kg that seems the quantity i can see the last ball media surface.

well i milled this 2,3kg for more 2,5 hours so now i've milled that batch for about 3+ hour.

now i want to know how i can know if my powder is milled enough.

i made some test:

1) burned as it is.
2) burned after granulated with about 2% dextrin

1) give me the same result of coffee grinded powder (test made some week ago in a *safe way*!)... but this is what i can say from what i've seen... i can't really say if it is 10% better or worst...
2) give me the result that 0,7g of granules seems to burn in a 'woosh' (so quicker than 1) ) ... but my impression is that it is not comparable with lift charge i find under commercial aerial shell... if i burn 0,7g of this last, it burn in a greater woosh and quicker (i can't say if much quicker or few quicker)

a thing is sure, the powder i have now is the finest i have nerver seen... it pack it self with very easy... in a plastic container , two tap tap on the wall are enough to create deep cracks and canyons in the powder...
i think that i will not obtain a finest powder milling it further. i want to make present that, before milling BP, i milled chems separately to airfloat grade.

so now the question is: how can i 'measure' my powder?
do your granulated powder have the same explosive power of commercial shell's lift charge?

how could i improve my bp if you also think my powder quality is not so good?

thanks

[Mortartube]

The only real way is to video a measured amount burning and then mill for longer and video the same weight again burning etc, until you find no improvement and then you can determine the best milling time. Always use the same mill, mill jar and amount of media. Always mill the same weight and most importantly TAKE NOTES!!!. It can save a lot of problems later.

Basically it's trial and error to find the optimum mill times etc as all mills are different.

The way you granulate powder can affect burn speed. If you press it into pucks to a known pressure, under an arbor or hydraulic press, you will get more consistent results than by ricing

[pyrotrev]

I've found the most realistic way to measure powder performance is some kind of ballistic test, as it's what it does when lifting a star or shell that matters. I've made a couple of little 30mm ID "mortars" fixed at ~40 deg to the horizontal, I put an accurate 1g of powder into these with a 20g aluminium slug as a projectile, then just measure the distance achieved by a firing. Using some commercial BP as a yardstick is also informative.

Edited by pyrotrev, 08 September 2011 - 12:26 PM.

[Karl Mitchell-Shead]

i milled 3kg batch for 30mins

There not laws against this ie 100g?! Although the OP is clearly foreign and as such domestic leglislation will not apply BUT for a new poster flicking through be worth endorsing our leglislation as a pointer?

[Creepin_pyro]

.

Edited by Creepin_pyro, 20 September 2011 - 04:44 PM.

[martyn]

just come from APC and had a sense of deja vu

[megabusa]

I measure the speed of each batch of BP to be sure it is consistent. I also measure the speed of my rocket fuel each batch.

You have to decide on a reasonably accurate way to compare the speed of each batch & then make adjustments to improve it.

I have a length of 'V' section aluminium secured horizontally.

There are 3 microswitches that are held closed with fine fishing line that pases over the track. The first & last switches are 1 metre apart.

The 'V' is filled with powder for it's entire length & the switch combination triggers a stop watch. When the BP burns the fishing line melts immediately & activates the microswitch.

I can then time how long it takes to burn a 1 metre length of BP which is approx 15g.

1 metre of my lift (which is made using a 'good quality' BBQ charcoal) burns in about 1 second. Willow burst is faster. Rocket fuel is much slower.


As a quick guide, a small pile (spoonful) of fast BP on a piece of paper should burn instantly with a 'wooof' & not leave any residue or burn the paper.


Cheers,

Phil.

Edited by megabusa, 09 September 2011 - 09:11 AM.

[Karl Mitchell-Shead]

Are you serious?

Yes, why? Are you saying you reccomend milling 3kg batches??!!

[Creepin_pyro]

,

Edited by Creepin_pyro, 20 September 2011 - 04:44 PM.

[Karl Mitchell-Shead]

If that's the optimal charge for the jar size, then obviously, yes.

Do you have acquire a keep for blackpowder under COER? If you do not then producing quantities of Blackpowder over 100g is illegal. And since UKPS is heavily orientated around practising the hobby in a legit fashion maybe you should think twice if you want to suggest people should mill such large batches.

Regardless of what you do yourself, in the public face of things you need to keep the advice straight!

[exat808]

Do you have acquire a keep for blackpowder under COER? If you do not then producing quantities of Blackpowder over 100g is illegal. And since UKPS is heavily orientated around practising the hobby in a legit fashion maybe you should think twice if you want to suggest people should mill such large batches.

Regardless of what you do yourself, in the public face of things you need to keep the advice straight!

well said.........

[Creepin_pyro]

.

Edited by Creepin_pyro, 20 September 2011 - 04:44 PM.

[Arthur Brown]

Assuming MSER even applies indicates a very restricted view. Forum members come from several countries. To my personal knowledge there are members in the UK, USA, South America, Geographer's Europe, India and Australaisia. Each of these countries will have their own legislation.

I'm certain that Pyrosailor99 is not in the UK.

[pyrosailor99]

guys i don't know why i've not received email about replies notification for my topic. maybe notification is not set as default setting in my profile. i will check...
Anyway i'm doing things in legal way. so don't worry about this.

anyway I thank you for suggestions about how to measure quality. i think balistic test (measure of flight time of a projectile) and microswitch speed timing are the best methods actually.