It occured to me that one can express the curve of pointed clay glandes as an arc of a larger diameter circle. Following this gived a certain projectile size and/or volume, one could calculate the diameter of said larger circle and the arc length of the projectiles curve.

Based on this, one could mark and cut out said arc length from a pvc pipe of the correct internal ø and use it to shape glandes from clay balls in a precise and repeatable manner, much like Aardvark shaper, but with longer lengths one could roll multiple balls at once. By using softened wax instead of clay, blanks for the lost-wax casting of bismuth projectiles (please dont sling lead around)
For a 60g clay glande I calculated the following:
(Assuming 15% weight reduction drying air drying and a density of 1.4g/cm³)

60g+15%≈70g clay
70g/1.4g/cm³ = 50cm³

Ellipsoid volume =4/3πabc, where semiaxis a:c = 1:2.5 for a 1:2.5 curve ratio, the same for semiaxis b assuming a circular crosssection. This results in the unsimplified formula being V=4/3π0.4c×0.4c×c

Solving for c with a 50cm³ volume results in c= 4.2cm, meaning a & b both = 1.68cm. These semiaxis are then multiplied by 2 to get the final gland dimensions; 8.4cm long, ø3.36cm

Using this calculator  https://www.handymath.com/cgi-bin/arc18.cgi?convrad=cm&convarc=cm&convwid=cm&con... one can then input the values of c and a to find the arc length and diameter of the circle. For the above projectile this is an arc length of 9.27cm and diameter of 12.18cm.
This diameter correlates roughly to the internal diameter of 125x3.1mm PVC pipe with an ID of 11.9cm, the arc length reflecting how wide of a section (measured on the inner wall of the pipe) to cut out.

These formula can course be modified for other curve ratios and projectile weights and densitys. For a 1:2 curve a and b each = 0.5c, for 1:3 0.3'c etc

I intend to build this in the near future, once I get my hands on a few kgs of clay. Until then I welcome others to come up with their own versions.

Great idea, can't have enough bullets
The shape you describe is a "tangent ogive": https://en.m.wikipedia.org/wiki/Nose_cone_design, an ellipsoid has no pointy ends if I remember correctly.
I have derived the equation for the volume of its solid of revolution and designed press molds for 3D printing. They work quite well. Maybe I find the formula somewhere

Making clay projectiles is not difficult. I use two methods. You have to practice a method a bit, but then it is the fastest method. The other method is also very simple. You can find them in kitchen supplies. They are completely perfect shapes. Search for kibbeh maker. It costs little money. It couldn't be more perfect.

Using 110×3.2mm Pipe I knocked up a quick test rig.

I measured my clay as having 2.09g/cm³ density before drying. After forming and drying the the oven (20% water loss by weight) the resulting test glande weighed 60g.

IronGoober wrote on May 29^th, 2024 at 8:21pm:

Pics resized.  We have instructions to help with this.  If you're working on a smartphone, a quick online search will likely get some instructions pretty easily.


And agree with IG.  That setup and the glande look great!

IronGoober wrote on May 29^th, 2024 at 8:21pm:


Yeah I'm relatively pleased with the result, just figuring out the technique to it as not all of them come out that nice the first try.

Thanks for the heads up

that's awesome!
So do you think long linear is better than making shorter parallel channels?

Concrete seems to like compression. I have tried with some 3d printed rollers and didnt work. maybe a different mix could work but I 'd stick with hand shaping with concrete. Pros are it is the cheapest and can be more durable than clay. Cons are it can be more messy than clay, needs gloves, requires more time to mix and get ready and you have less time to work with before it sets.

if it is easy to slide the pvc pipe as it is, you could have 5-10 parallel channels each making 5 projectiles producing 25-50 projectiles in one roll. I'd use plywood for the frame. If this is achievable that would really make me interested in clay.