Do I need a ball mill?
In a technical sense, you do not NEED a ball mill, but it's hard to progress too far in the hobby without one. They are by far the simplest, most cost effective, and least labor intensive methods to create black powder, and powder reasonable amounts of chemicals. They are also frequently used to create charcoal streamer compositions, such as tigertail (TT), Chrysanthemum 6 (C6), Chrysanthemum 8 (C8), and spider stars. When properly done, these are some of the most beautiful and elegant effects, along with being some of the simplest to create.
In doing research into black powder, you've probably come across several other methods.
Mortar and pestle – This can by all means be used to make serviceable compositions. It is potentially faster than a ball mill to make black powder, or other compositions. They are also useful to powder small amounts of chemicals. It has the disadvantage that it is extremely labor intensive relative to a ball mill.
CIA Method – This is done by rapidly precipitating out KNO3 with cold alcohol in the presence of charcoal and sulfur. This may be the fastest overall method to make black powder. It however is a rather expensive method with the rising costs of alcohol. It also requires the chemicals to still be finely powdered somehow.
There are numerous other methods I've seen over the years that are simply not safe. These include using a blender to mix the ingredients. Similarly coffee grinders have been proposed. There is a similar method currently being used to manufacture black powder for the military, but rest assured more precautions are taken that can be provided at home. There is one method I've seen proposed that utilizes a blender and alcohol or water slurry. I cannot comment on this, as not enough research has been done, but I however still would not suggest it.
Where can I purchase a ball mill?
Most people started with a rock tumbler. They are available at the lowest cost at Harbor Freight, running around $20 to $30. You will still need media. Lead shot is the most recommended media. It is cheap, and easily obtainable. It has a few disadvantages, namely the media will slowly wear away exposing both you, and the environment to lead. Brass has come under heavier use recently. It is harder to find in a ready to use form, and often is cut from longer rods, which require a few tools that one may not have on hand.
Rock tumbler: http://www.harborfre...temnumber=65838
(I chose the largest shot of the same price range.)
For approximately $45 you will have a functional ball mill and media, capable of creating BP in 8-12 hours. People have recommended going as long as 24 to 48 hours using the same setup. One will have to do some tests to determine when the quality of their BP is up to snuff. It has as much to do with the chemicals as it does with the machinery. I recommend taking a small sample every 4 hours for the first 12 hours, and then every 12 hours after that. Video taping the burn tests will give an easy way to compare.
As you advance in the hobby, a larger mill is often desired. Most are built to suit, but an appropriate mill can be purchased as well to an extent.
The 15lb mill will make approximately 1 kilo of composition in 4 hours. I will leave the media up to you. You will need approximately 150 ¾" x 1" cylinders. If using another size or shape, this corresponds with approximately 30lbs of lead, 18lbs of stainless steel, or 12lbs of ceramic.
What media should I use?
I consider there to be only 3 generally acceptable media for live materials. Lead, which can be cast to suit, or purchased as large caliber shot. 50 caliber is good for most mills. Stainless steel can be purchased as rod, and cut into appropriate lengths. Brass can be treated in the same way. It'd encouraged to somehow clean up the ends with a grinding wheel to avoid tearing up your jar. Be sure to check incompatibilities of these medias still.
Ceramic media - Ceramic CAN be ok. There is a firm, Coors-tek, that makes a non-sparking media for the explosives industry. If you are not 100% positive it came from this firm, and that it is designed to be non-sparking, save your ceramic for single chemicals. It is excellent for single chemicals actually.
Coinage - The money you're going to be LITERALLY putting into your mill will likely be enough to buy some lead shot. $10 of lead will be enough to fill a 3lb rock tumbler. I'm not positive on it's sparking or corrosion status either.
Glass Marbles - They will chip, and there is concern over sparking. I know you probably have a million lying around, but it's not worth it.
Rocks – I think this should be self-explanatory.
Making your own ball mill
For the more mechanically inclined, this is generally the preferred approach. There really is no right or wrong way to make a mill. Dozens of designs can be found by looking at pictures of other mills. I hope to include some here in the near future to give you some ideas.
There are a few important things to include in a design:
Exclude the motor from the ball milling area.
There are a few reasons for this. It will allow the motor to be properly ventilated. It also prevents any sort of powders from getting into the motor in case of a spill.
A motor capable of turning a full load.
For a 1 kilo sized jar, this will corresponds to a ¼ to ½ HP motor. It's better to go too big than too small. Do research on the appropriate type of motors, and what will work for you. Be sure to check the voltage, number of phases, if it requires a starting capacitor, how is it meant to be attached, as well as how it is cooled. TEFC stands for totally enclosed fan cooled, which is probably ideal.
An appropriate pulley ratio to get an ideal speed.
Below is a RPM calculator. There is an excellent one on passfire as well, if you are a member. The one below will require two calculations. The first should be self-explanatory. The second one, treat the diameter of your driven shaft (including any rubber wrapping) as the drive pulley, the diameter of your jar as the driven pulley, and use the RPM of the first calculation, as the input RPM. Don't worry about the other stuff so much.
The rest of the materials
This is where the fun comes in. The rest is really up to you for design. Below are some helpful hints though.
Searching under the term "pulley" may yield aggravating experience when looking for supplies. The term "sheave" will hopefully give more fruitful results.
Idle rollers, such as used on conveyer belts, make excellent undriven shafts.
Pillow blocks are generally used to reduce friction, but I've seen people mount other sorts of bearing into wood, as OTC as skateboard bearing with success.
Some are fans of placing the motor on a hinge, and using gravity to tension the belt.
Use lift bars in your ball mill jar.
Why isn't my BP any good?
- Are you using a ball mill?
- Did you follow the above advice with regards to obtaining a mill?
- Did you try milling for extended periods of time?
- If you've wet and granulated/corned it, have you waited at least a week for it to dry?