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Making Stone Biconicals? (Read 2248 times)
Hirtius
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Making Stone Biconicals?
Mar 11th, 2021 at 12:46pm
 
I recently tried to make a shaped sling stone like those used in the Pacific. I've seen Timpa using a grinder. I'm trying the old fashioned way, which has involved a lot of grinding against a stone. However, I've found that I am completely unable to make an impact on the shape of the rock. I can grind off the smallest bits, but anything more is proving impossible. I spent an hour with no change to a small rock, I can only imagine how tough it would have been for people making a bunch of them.

I think part of what I'm struggling with is that the grindstones I'm using might be weaker than the rock I'm trying to shape. We have a lot of limestone in the area that I live, and those are what the larger stones are made out of. However, that gets smooth with little change in the stone I'm trying to shape.

Does anyone have any tips?
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Kick
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Re: Making Stone Biconicals?
Reply #1 - Mar 11th, 2021 at 12:51pm
 
It comes down to the materials. Softer slingstone, harder grinding stone.
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AncientCraftwork
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Re: Making Stone Biconicals?
Reply #2 - Mar 11th, 2021 at 1:21pm
 
My tip is screw the stone and opt for clay. Too much effort for a stone biconical in my view for something thats likely to be only thrown once.
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David Morningstar
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Re: Making Stone Biconicals?
Reply #3 - Mar 11th, 2021 at 1:41pm
 
Your grindstone must be of harder material. Typically people used a large rock stuck in the ground and moved the piece to be shaped against it.
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NooneOfConsequence
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Re: Making Stone Biconicals?
Reply #4 - Mar 11th, 2021 at 1:50pm
 
A little patience and a sandblaster might do the trick

https://m.youtube.com/watch?v=OVGt1nIyN3o
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“My final hour is at hand. We face an enemy more numerous and cunning than the world has yet seen. Remember your training, and do not fear the hordes of Judas. I, without sin, shall cast the first stone. That will be your sign to attack! But you shall not fight this unholy enemy with stones. No! RAZOR GLANDES!  Aim for the eyes! May the Lord have mercy, for we shall show none!“  -Jesus the Noodler
 
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Jaegoor
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Re: Making Stone Biconicals?
Reply #5 - Mar 11th, 2021 at 2:06pm
 
I have often asked myself this question.  It used to be done with water.  This is how stone balls were made for cannons.  Of course, you can also just sand by hand.  But the effort and the time is too big in my opinion.  It's not plausible.
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Sarosh
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Re: Making Stone Biconicals?
Reply #6 - Mar 11th, 2021 at 2:47pm
 
recent similar post here: https://slinging.org/forum/YaBB.pl?num=1612679736/6#6

Sarosh wrote on Feb 7th, 2021 at 10:46am:
https://youtu.be/nOxtdcgNDXI?t=188
^Timpa used a grinder, 5minutes for 2 stones, it is very fast. of course it is very noisy and you have to wear good dust protection. would not recommend for urban area.

Jaegoor wrote on Mar 7th, 2021 at 7:34am:
There used to be so-called ball mills.  These were operated with water.  Today they are rare.
https://youtu.be/B8JgKgrT00E


in ball mills video it doesn't show how they roughly shape the stones to ball. maybe it can be done with a bushing hammer i dont know.
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Sarosh
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Re: Making Stone Biconicals?
Reply #7 - Mar 11th, 2021 at 3:02pm
 
lol I answered before reading everything.
I have tried 60 grit flap disk with a small angle grinder it was not effective.
Maybe you should learn about the different carving stone methods like the bushing hammer and chisels.
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Martin_Greywolf
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Re: Making Stone Biconicals?
Reply #8 - Mar 11th, 2021 at 5:18pm
 
Jaegoor has it right, almost no one from stone age onwards did this sort of stone work by hand - water or pedal/handcrank powered grinding wheels were the rule of the day - and they could get pretty big. Using electricity instead of an apprentice to power said grinding is perfectly fine.

The stone RPM is, of course, slower with the historical way of doing things, but still much, much faster than doing it by hand.

As for what would they do if they didn't have a readily available helper or a water wheel, I suspect they wouldn't have bothered with grinding the stone.

Image from 1560s:
...
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Re: Making Stone Biconicals?
Reply #9 - Mar 11th, 2021 at 5:23pm
 
Its all about the Mohs scale. Try to grind a diamond with an emerald good luck. Try to grind two stones of the same or close hardness...good luck.

Get a substantially softer stone and grind it against a rough very hard stone. For example I grinded some beach pebbles. Certain things would barely touch it while other things put a pretty good wear on it after just a minute or two. And these werent soft stones. Keep water near by and continuously splash the grind stone to keep it clear of particles and to help guard against silicosis. Do this on a day with a constant breeze blowing with the water is best.

This is like fire by friction. Theres more to it than just the motion. You need the right materials as well.
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Jaegoor
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Re: Making Stone Biconicals?
Reply #10 - Mar 11th, 2021 at 5:52pm
 
Yes.  The hardness of the materials plays a role.  But not necessarily.  I have already drilled granite with an elder stick and sand.  But it takes a long time.  In a ball mill with water it takes about a day.  It takes several days by hand without additional tools.  Apiece.  In Guam you can find a lot of historical slingstones in biconical form.  I can hardly imagine that all of them were only processed by hand.  Above all, there are a great many good natural stones.  So why work forever on a biconical stone?  Maybe they were jewelry.
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Re: Making Stone Biconicals?
Reply #11 - Mar 11th, 2021 at 6:53pm
 
Not all of the stone biconicals in Guam are jewelry.  Maybe some for religious purposes but they sanded stone down themselves, not with technology.  Go talk to the Guam members here.  Native cultures just did thier thing.
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Jaegoor
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Re: Making Stone Biconicals?
Reply #12 - Mar 11th, 2021 at 7:00pm
 
Yes, I have spoken to some from Guam about it.  Even with archaeological experts there are different opinions about it.  Some are very big
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Re: Making Stone Biconicals?
Reply #13 - Mar 12th, 2021 at 2:57am
 
Two examples :

First in Polynesia. Soapstone was used. It is a hard rock but easy to sculpt.

Second in France. Chalk was used. It is a hard rock but you can use a knife to sculpt it.
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Jaegoor
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Re: Making Stone Biconicals?
Reply #14 - Mar 12th, 2021 at 5:45am
 
In Guam there are also stone glandes made of very hard material.  And there are some that are really big.
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Bono Mellius
 
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