Anyone good at making flint/obsidian/stone/glass knives?

L

Lagrangian

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Jun 25, 2011
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Is anyone here that is good at knapping flint or obsidian to make arrow-head or spear-points?
http://en.wikipedia.org/wiki/Knapping

Since obsidian can produce insanely sharp edges, I'm curious about it. Obsidian knives are _literally_ a hundred times sharper than a conventional razor. :eek:

So I thought it would be fun to make a edge 100x sharper than my regular knives, just to see what it can do. I might try to fracture some glass bottles, but the problem is I don't know how to make the fracture have a shallow angle, like say, 20 degrees inclusive. Those arrow-heads and spear-points I see in documentaries look pretty darn thin....

I'm not saying a glass knife is practical; I'm just curious out of a sense of fun, but I have no experience with this. Is there anyone who has expertise here?

Sincerely,
--Lagrangian
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"What grit sharpens the mind?"--Zen Sharpening Koan


P.S. Here are references showing that an obsidian knife is 100x sharper than a conventional razor:

According to Prof. Verhoeven, a modern sharp razor has a sharpness of 0.4 microns.
http://mse.iastate.edu/fileadmin/www...nifeShExps.pdf

Concoidally fractured obsidian has an sharpness of 0.003 microns.
http://en.wikipedia.org/wiki/Obsidian
 
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Lagrangian said:
Is anyone here that is good at knapping flint or obsidian to make arrow-head or spear-points?
Click to expand...

neanderthal3.jpg
 
@Razorsharp-Travis:
All the glass breaking I've seen produces included angles of around 90 degrees. Any thoughts about how to produce a very thin shard? I've seen videos of knapping obsidian, but I don't think that will work on glass bottles. :p

@singularity36:
lol! :)
So.... You know these guys? How can I contact them? :monkey:
 
What's also interesting about obsidian is that while a steel or other type of metal blade has irregularities there are almost none with a good obsidian edge.
 
There are several yt videos of people knapping arrow heads out of the bottom of glass bottles. It's pretty neat. I have always been intrigued with knapping but it looks like something that takes years of intense practice to be good at.
 
It is like many other hobbies. It takes a short while for a dedicated individual to get pretty good at...but a lifetime to master.

I have watched guys knapp chips that were as sharp as you can imagine. Those chips by themselves take a fraction of a second to make, and each chip could serve as a small cutting tool if held carefully;)
 
@Obsessed with Edges:
Thanks! :) I'll be sure to check out that thread, subform, and search around!

@singularity35:
Dang it... I can't find my DeLorean... Either it was towed, or car-jacked! :D

@everyone:
So can I ask a dumb question? For those of you who have knapped and made extremely sharp chips:

Will it cut a free-falling-hair?

If the answer is no, then I'm not going to believe anyone here can get a metal knife to cut a free-falling-hair. (Assuming that the chip you knapped out has a low total included angle.) To me, given that obsidian edge can be 100x sharper than a razor, well that would be pretty conclusive in my mind.

What do you think?

Sincerely,
--Lagrangian

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"What grit sharpens the mind?"--Zen Sharpening Koan
 
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Lagrangian said:
@everyone:
So can I ask a dumb question? For those of you who have knapped and made extremely sharp chips:

Will it cut a free-falling-hair?
Click to expand...

You can test this yourself pretty easily. Grab a glass bottle and break it. Carefully search through the shards for the piece with the most acute fracture angle you can find and test it out.
 
I used to do a lot of flint/obsidian/glass knapping years ago. It's a good idea to practice on glass bottle bottoms as they are free! You can also knap agate as well as noviculite, so there is a use for your old worn out Arkansas stones.

These days I carry a square piece of flint in my pocket when traveling by air. If someone tells me I can't carry a knife, I want to be sure that I have one... and there is no regulation about carrying rocks when flying. In the past 100 flights it's never once been even questioned. The piece I carry doesn't look like an arrow hear or spear point, but it will cut through a 1/2" hemp rope easily.

A couple of points (no pun intended.) First, neither flint nor obsidian get any sharper than a very well sharpened knife. I can certainly get my Benchmade as sharp or sharper. Second, a very acute edge on flint chips off with the first cut, but there is no need to get it so acute to be sharp. Third, if you are going to do some knapping yourself, be sure to do it outdoors with the wind blowing across you and not at you. There will be hundreds of micro sized chips coming off as well as small flakes. Be sure to wear a dust mask too. Don't knap in an area where dogs or cats will be walking around.

Keep in mind that knapped edges are for 'slicing,' not push cutting.

Now, get yourself some old glass bottles, a few pieces of very heavy leather for hand and leg pads, a couple of 'boppers' or an 'ishi stick' and get cracking!

Stitchawl
 
stitchawl said:
These days I carry a square piece of flint in my pocket when traveling by air. If someone tells me I can't carry a knife, I want to be sure that I have one... and there is no regulation about carrying rocks when flying. In the past 100 flights it's never once been even questioned. The piece I carry doesn't look like an arrow hear or spear point, but it will cut through a 1/2" hemp rope easily.
Click to expand...

Uh oh... NOW you've done it! :eek:

Somewhere, in a dingy cubicle deep in the bowels of the TSA, an employee is sitting at his computer, taking notes and preparing a memo, to update the 'Prohibited Items' list on airline flights. "No SHARP ROCKS allowed!!", is what we'll see posted at the security checkpoints next time... :D

Just kidding, Stitch. Good to hear from you again. ;)
 
Einstein said we will use rocks on the other side...little did he know the forces that would lead to this end.
 
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