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&convhei=cm&convapo=cm&convtet=deg&convare=cm&rad1=&arc1=&wid1=10.6&hei1=2.12&apo1=&tet1=&are1=&submit=Calculate&numnum=1&moreless=1&decimal=5 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.

good idea on the pvc pipe channel.
I wanted to make a parallel array of channels to produce 10-20 projectiles at once. The dosage for each channel could be made by rolling clay into a long cylinder and then laying on the channels (like a pill roller) theoretically the same could be applied on concrete using a pipe to make a long concrete cylinder for the dosage.
but concrete needs compression so it didnt work. I abandoned the project because of the high prices of the 3d printed channels and clay price.
your idea might work with clay if you figure a way to make the parallel pvc channels stable.

in my case clay is expensive and it would make sense only if it was fired cheaply.

this is the first time I hear of bismuth projectiles, some people use pewter instead of lead. I personally would love some forged steel biconicals instead of lead

Great idea, can't have enough bullets :D
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

I'm surprised that there had been less discussion on lead alternatives (not that I have directly searched for it) given the risks and toxicity for both the processor and the environment. Bismuth has none the toxicity and a low melting point.

As for clay, a 10kg block (6€) would get me around 150 glandes at 3cent a shot. Rocks slung over field have a nasty habit of damaging mower blades... That and the consistency of clay glandes makes them a better option for me.

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.

A bit of help from Sketchup and chatgpt has given the attached formulas for finding the volume and length of 1:2.5 pointed glandes. Enough with the maths, time to head to the workshop... ;D

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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.

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That's beautiful man.

FYI, you should size your images down to about 20% of their original size to post, otherwise they show up huge.

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

FYI, you should size your images down to about 20% of their original size to post, otherwise they show up huge.

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! :thumb:

great result.
have you tried producing more than one at the same time?

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

That's beautiful man. FYI, you should size your images down to about 20% of their original size to post, otherwise they show up huge.

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

Sarosh wrote on May 30^th, 2024 at 2:01am:

great result. have you tried producing more than one at the same time?

With a 1m length, up 5 at a time has worked so far

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

Sarosh wrote on May 30^th, 2024 at 5:10am:

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

I think so. The only issue I've had so far is that occasionally two glandes may roll together and bind. With parallel channels it may be a bit cumbersome to exert equal pressure in the rolling direction. Ideally with this set up one drops in the 5 clay blobs spaced out but to side of the channel, then swipes the top roller across and the formed projectiles roll out the other side.

The limitations of my test rig so far:
- It would benefit from more rigidity (I did mount a long wooden strip on the top roller), either with the lower channel supported by frames or just expanding foam
- the cuts could definitely be more accurate or sanded down so that all edges are 100% parallel
- as the upper roller is unfixed, it does have a bit of "slop". An adapter to ensure only linear motion will be one of next upgrades.

On a side note, I recently watched your video on making concrete projectiles; kneadable concrete would most likely work with this method too. I saw a formula for it somewhere on the german internet..

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.

The formula for the kneadable concrete is as follows:

1kg coarse sand
1kg fine quartz/silica sand
1kg Cement
500g Cement based tile adhesive
2% by weight of fiber
600ml Water

Source: https://tinyurl.com/2cexxy9c

Thanks for the recipe and the link. :thumb:

Now the main question.  If you make one of those, let it dry, and sling it against a target, what does it look like afterward?

Jaegoor wrote on May 15^th, 2024 at 1:26pm:

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.

I tried a Kibbeh maker today but I had no end of problems with the unmoulding. Do you use anything to stop the clay sticking?

Oil, grease or talc ?
;)

irgendeinekiwi wrote on May 30^th, 2024 at 8:54pm:

The formula for the kneadable concrete is as follows: 1kg coarse sand 1kg fine quartz/silica sand 1kg Cement 500g Cement based tile adhesive 2% by weight of fiber 600ml Water Source: https://tinyurl.com/2cexxy9c

Tested today;
600ml of water was too much, I had to add more of the other ingredients. The formula needs a bit of revision, as it doesnt behave quite like clay does in my roller, I'm guessing a tad more tile adhesive. I ended up using just the lower section as a rolling surface to form the projectiles by hand. Once they are cured I'll see how durable they are.

I made a few more clay glandes well. They are great to shoot and I've already gone through 10kg of clay. A better constructed roller and a dosing scoop would speed things up, 2hrs of work for 20mins of slinging wasnt quite my intention ;D.

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thanks for sharing the results. some of those concrete slugs are very nicely shaped( 2nd, 4th, 5th from low left.) If you plan on going for range shots consider sanding and painting the concrete.


irgendeinekiwi wrote on Aug 11^th, 2024 at 7:14am:

2hrs of work for 20mins of slinging wasnt quite my intention

nothing beats a natural source of stones
maybe steel rods cut with hydraulic cutters could be as fun (relatively cheap and more durable than stone/clay/concrete/lead)

Sarosh wrote on Aug 11^th, 2024 at 10:01am:

thanks for sharing the results. some of those concrete slugs are very nicely shaped( 2nd, 4th, 5th from low left.) If you plan on going for range shots consider sanding and painting the concrete. irgendeinekiwi wrote on Aug 11th, 2024 at 7:14am: 2hrs of work for 20mins of slinging wasnt quite my intention nothing beats a natural source of stones maybe steel rods cut with hydraulic cutters could be as fun (relatively cheap and more durable than stone/clay/concrete/lead)

Steel rods can be quite terrifying if they ricochet; especially if you shape them into biconicals

Sarosh wrote on Aug 11^th, 2024 at 10:01am:

thanks for sharing the results. some of those concrete slugs are very nicely shaped( 2nd, 4th, 5th from low left.) If you plan on going for range shots consider sanding and painting the concrete. irgendeinekiwi wrote on Aug 11th, 2024 at 7:14am: 2hrs of work for 20mins of slinging wasnt quite my intention nothing beats a natural source of stones maybe steel rods cut with hydraulic cutters could be as fun (relatively cheap and more durable than stone/clay/concrete/lead)

The main time killer was individually weighing out each lump of clay/concrete. I might try and build a trough type thing like you tried a while back, but out of a few offcuts of wood I gave laying around, sanded then sealed

irgendeinekiwi wrote on Aug 12^th, 2024 at 11:40am:

I might try and build a trough type thing like you tried a while back

I started with a trough which was also taking time then used a pvc pipe  thinking that a cylidrical shape would be easily shaped into a pill but the pipe was trapping air increasing times and inconsistencies. I ended up using a short pipe cut off that was the volume I wanted each projectile, I picked up concrete from the bucket with that and shaped the concrete by hand.

I'd say concrete wins only in price, it can't win in time spent.(just because it needs mixing)
The good with clay is that maybe you could fire it and be more durable than concrete.

I think the only way to have concrete win timewise would be to make up a PU / Silicone mould with multiple cavities then use a casting concrete formula with added plasticiser and accelerator.