Black powder puck density

[All10Fingers]

I'm working on corning my black powder. If I'm making 25 gram pucks in a 40mm die, about how thick should the puck be to achieve the desired 1.7g/cc? 

My first post so I hope everything is as it should.

[Arthur]

25g divided by 1.7g/cc = 14.7cc  Puck volume

puck area = (pi x r(squared)) 3.142 x 2 x 2 = 12.56 

14.7 / puck area = puck height 

14.7 / 12.468 = 1.17 centimeters

 

Is my suggestion. BUT with all things pyro the theory may be right but does it really work? You'll have to try it, remembering that it's hard to make a thick puck that's consistent all the way through. Also consider the powder moisture content, too wet and the nitrate dissolves partially in the water and this squeezes out to waste, too dry and the powder isn't lubricated into the puck as it's pressed. It's also hard to get big grains from a thin puck! the finished puck only needs to be 3 - 5 mm thick to get 0FA to 6FA when corned. between pucking and corning comes drying.

try 15g, 20g 25g and 30g portions and see what the puck is like then pick the best.

[All10Fingers]

Allready made these. They look...a little over a centimeter. Some are a little thicker than others but thier each "about" 25 grams. For water, I used literally two spoonfuls in 200 grams straight from the mill. Squeezed in a 12 shop press

[Arthur]

Store them as pucks, but try to form granulated powder in the grades you will need, as a guess the pucks are OK to a bit thick. They will corn but the moisture may influence the grades available easily.

[cmjlab]

Those are some nice looking pucks!  😉

They really do look nice and solid, how did you press them, and what did you use a store bought die or homemade?

[All10Fingers]

I used a hand cranked 12 ton hydraulic press from the 80s. The die is from Amazon. It's a  rosin "pre press mold" meant for preparing weed extracts.

[DavidF]

That's a good find. You could make a ring-shaped sleeve and slip it onto the plunger so that the stop on the plunger bottoms out onto it when pressing. Then you can press pucks of a known, pre-determined thickness. You can then calculate the finished volume of your puck, and add an appropriate weight of powder to press a puck of known density, consistently every time. That's how my small puck die works. I calculate for a density of 1.7 without the water, and then add it. That ensures the density is a 'titch' over 1.7 because the puck will always retain 'some' water.

I use a known, exact amount of water when dampening the mill dust. Then I screen it twice through 10-12 mesh, hand mixing in between screenings. Then the powder is left to temper overnight, and perfectly consistent pucks can be produced with ease. I made a wooden base with a hole in it to accept the sleeve, so the puck can be popped out conveniently. I use 2 1/2% water to dampen the powder.

If the puck is at least 1.7g/cc, that can be proven by immersing it in 99% isopropyl alcohol (NOT 91%) for 30 seconds or so and drying it off. If the puck does not gain weight from absorption of the alcohol, it's at least 1.7g/cc. That's a little trick from Edwin Brown, a respected expert in the area of black powder and rockets.

Is that tooling really all stainless steel? I think Woody's are all aluminum in the smaller sizes.

[All10Fingers]

2 hours ago, DavidF said:

That's a good find. You could make a ring-shaped sleeve and slip it onto the plunger so that the stop on the plunger bottoms out onto it when pressing. Then you can press pucks of a known, pre-determined thickness. You can then calculate the finished volume of your puck, and add an appropriate weight of powder to press a puck of known density, consistently every time. That's how my small puck die works. I calculate for a density of 1.7 without the water, and then add it. That ensures the density is a 'titch' over 1.7 because the puck will always retain 'some' water.

I use a known, exact amount of water when dampening the mill dust. Then I screen it twice through 10-12 mesh, hand mixing in between screenings. Then the powder is left to temper overnight, and perfectly consistent pucks can be produced with ease. I made a wooden base with a hole in it to accept the sleeve, so the puck can be popped out conveniently. I use 2 1/2% water to dampen the powder.

If the puck is at least 1.7g/cc, that can be proven by immersing it in 99% isopropyl alcohol (NOT 91%) for 30 seconds or so and drying it off. If the puck does not gain weight from absorption of the alcohol, it's at least 1.7g/cc. That's a little trick from Edwin Brown, a respected expert in the area of black powder and rockets.

Is that tooling really all stainless steel? I think Woody's are all aluminum in the smaller sizes.

Yes it's all stainless. It's heavy, like even when you're expecting it, it's still surprisingly heavy. All parts are milled from one solid piece. And the tolerances are immaculate. I found it on sale for around 30 bucks and bought the last two.

[cmjlab]

I don't puck my B.P., but if I did it'd sure be nice to find a deal like that.  I can't think of any stainless steel tools with that much weight to them,  that would cost that little! I can't even find a chunk of stainless steel blank that size for that price   That was a lucky find!

[Arthur]

Don't know about OP's puck tool, but, I saw one once that was a piece of plastic 2" drain pipe with two sliding pieces of polyester resin cast in situ to make upper and lower pistons inside the tube 37g made an 11mm thick puck.

[Arthur]

BP was always milled and pressed into pucks then the pucks were stored til needed. This ensures that a factory could always break down pucks into the sizes ordered by customers (inc army and navy). SO pucks would be corned (broken into wheat grain size pieces) as needed. These pieces would then be sieved into mesh cuts and some would be graphite glazed.

 

[ThrownBiscuit]

I'm jealous that you were able to find a stainless steel press that cheaply.  Mine is made of aluminum and makes 3" diameter pucks made from a piece of 3" rod and 3" ID tubing and a paper plate taped onto a piece of 1" thick plate. I use my 12 ton harbor freight press.