Black Powder Die
Once you've mixed and milled your black powder you'll probably be anxious to start using it. Sorry...it's not quite ready. The powder that comes out after milling is called meal powder. While it is useful for many things such as priming and making fuse, you need to process it further to make it into grains for purposes such as lifting. That's where this tool comes into play. It's my homemade pressing die. With a little work, you can greatly increase the efficiency of your powder. Thanks to Lloyd Sponenburgh for the design and details and to Dan Williams for posting them along with additional info.
The first step is casting the pistons. They are made from a mixture of silica sand and polyester resin. I was a little nervous to follow Lloyd's recommendations for materials as I had never worked with fiberglass. It was actually pretty simple. I used 3 inch ABS pipe for the forms, painted sparingly inside with a mixture of petroleum jelly and tolulene. The base piston is 13.5 cm tall and the top is 5.36 cm. I cut the pipe just a hair longer and clamped them to a piece of foil covered wood (also painted with the mold release). You need 24oz of resin and 32oz of sand. Since Lloyd recommends cutting back to 60% of the recommended hardner, the math becomes simple. Use exactly half of the hardner directed for a full quart. Then mix in the sand thoroughly (use an old or glass container because the only way to clean up this stuff is with acetone). Pour into the molds and let cure, I left mine overnight. Then they should slip out of the molds with minimal force. Once they're cleaned up, the base piston fits in a piece of ABS pipe 5 inches tall. The dimensions are important to enable the powder to be pressed to a specific density. This picture shows how the base piston extends .8cm beyond the base.
Here you see the top piston along with a 3 inch section of 3 inch diameter ABS pipe. This pipe becomes the chamber where the powder is pressed. It sits on top of the base pipe over the .8cm portion of the bottom piston and is supported by a repair sleeve and hose clamps.
Here is the die ready for use. It shows how everything fits together with the clamps. The top piston has a reference mark 1.46cm below the top to indicate when 8oz of powder is properly pressed. The mark isn't visible because I need to darken it with a permanent marker (you can't etch on these things to save your life). To press 4oz, the piston is pressed flush with the top pipe. The cakes of powder obtained after pressing are then broken up and screened into various mesh sizes corresponding to grain size. You can read a little more detail about this on Dan's Page.