33 replies to this topic

[Flashy]

Hi there,

My BP doesn't have the same problems as this stuff but i didn't want to start a new topic. This is a link to a movie of 1 gram of my BP burning. Its only been milled for half an hour but it burns very slowly. It also leaves a horrible mess behind shown in the picture below. Any one got any ideas whats wrong with this stuff?

BP Movie

[Richard H]

It's either down to poor incorperation of the KNO3 / Charcoal / Sulphur, incorrect weighing of the components, or possibly both.

The first and most important thing is weigh everything accurately to 0.1g

Could you describe your ball mill and milling media to me? How much media do you use in the jar? What is the RPM of the jar?

[Flashy]

I weigh on a scale that is accurate to 0.1g and that is not the problem. I use a 5 inch PVC pipe with end caps for my milling jar. The jar spins at around 80RPM, i usually use 7 to 10 20 mm lead balls as my milling media. Could this problem be caused by "Dirty" KN03? I bought the KN03 from ebay, so i'm not sure how pure it is. I don't have much of it left so i'm putting in an order to www.timstar.co.uk.

[lord_dranack]

How long did you mill it for?

[dfk]

either mill longer with that amount of media (24 hours) maybe more.
or use more media, it seems your powder is nowhere near mixed enough.

[lord_dranack]

You need much more milling media!
Filling the jar half full of media, then a quater full of green meal is often recomended.

[Flashy]

Where do you all buy milling media? I don't have the facilities to cast my own media. I'm going to try and buy some from a gunshop tomorrow, the shot they use in cartridges for killing geese. I'm not sure if they will let me know it though, the guy that owns the place is strange to say the least.

[lord_dranack]

This has been answered many timed in the past! Search through previous topics!
You don't want lead shot. You need about 0.5" musket balls.

[Flashy]

Ok well i've searched the forums and i still can not find where to buy musket balls from. I do not want to order over the internet. Do gunshops sell this kind of thing?

[Phoenix]

You probably do have the facilities to cast your own media (though it might not look as nice as sasman?s). Get a piece of wood about 20mm thick, and drill a load of ~15mm holes through it (or larger, perhaps) Get another piece of wood and a few G clamps, clamp the hole board onto the other piece, to seal the bottom of the holes. Get a saucepan that you aren?t going to need to cook food in again (or, in a pinch, a bean can and some tongues, but this is not recommended), and a lot of scrap lead. Wheel weights are apparently the most common source, but another easy place to find it is in skips at building sites where lead flashing has been put on houses or where church roofs are being restored (I don?t know if that applies in the rest of the world, but in the UK churches very often have lead roofs). Guess at how much lead you will need to fill your board full of holes (if you get it wrong it doesn?t really matter ? better luck next time) and melt it in the pan. The heat source can be a camping stove, or even just a wood fire, but make sure that you do this outside, and keep yourself and anyone else in the vicinity upwind of the fumes. Once it has melted, pour it into the holes, allow it to solidify, remove the bottom board, and the poke the cylinders out. Lead melts at 328*C, so the mould should not be significantly damaged and can be reused. Do not pour water onto the mould to cool the lead quicker, as if the mould is wet, the water will boil when the next batch of lead is poured in, and spray molten lead all over you. It may not be hot enough to damage the wood much, but it does hurt!

[Richard H]

Any blackpowder firearms dealer will sell musket rounds, luckily I have a very large dealer rather close to me.

Alternatively, like I do, use brass round bar from an engineering supplier. About ?30 of brass was enough to fill my jar correctly (1/2 full of media).

[bobconan]

hehe. My jar cant handle being half full of media. Im guessing because its not round. The wood method is good thats how i made like 10 pounds of media. It does made alot of bad casts tho (15%)and they come out very porous from the grain of the wood. You definetly need antimony and tin in the mix tho. I bought Ingots with 12% Sb and 6% Sn from www.midwayusa.com

Edited by bobconan, 18 June 2004 - 02:44 AM.

[bmiller14]

For my media I just used lead fishing weights a little bigger than marbles and twisted off the loop so far it has worked very well.

Edited by bmiller14, 18 June 2004 - 05:56 AM.

[bobconan]

I did that to but when i milled just plain chems they came out grey

[Kembang Api]

There are several criteria involved in Milling media selection,
1. Size
2. Weight
3. Hardness
4. Sparking characteristics
5. Corrosion resistance
6. Cost
The most critical are Sparking Characteristics (life and death) and corrosion resistance to some chemicals especially Potassium nitrate. Size and weight are the most important criteria in determining the weight of each ball and the speed of the ball mill machine. Cost can be an important consideration.

Choices of Milling Media are,
1. Lead
2. Steel
3. Brass
4. Glass
5. Ceramic
An excellent choice is ceramic ball and Brass offer the advantage of being non-sparking but both are costly. My choice is fishing sinker and lead shot from BP Firearms.

Milling speed is the most critical and is tied up with the ratio of the diameter of the mill to the diameter of each ball. As a general rule of thumb for dry milling, the ball mill's speed should be run at 65% of the critical speed.

The formula for the critical speed is :
265.45 / √ milling jar i.d. ? ball o.d.

Stamp and Wheel milling considered mandatory in wet milling. It is just too dangerous to run in dry. Ball milling can be done wet for some materials but for Black Powder it is best in dry form.

Charging of material into the ball mill should limit to 25% and 50% of milling media. This is the most optimal quantities at 65% of the critical speed of the milling machine.

I hope this can be useful information.