Obsidian Knife Texture

JTknives

JTknives

Blade Heat Treating www.jarodtodd.com
Knifemaker / Craftsman / Service Provider
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Jun 11, 2006
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I am working on a knife that i want to have an Chipped Obsidian knife look but be made from steel. I have been doing some experimenting With a 400,000 rpm air grinder and its working ok but thought i would see if anyone had any tips on how to archive this look. I will post a picture of what I'm getting sofar. Thanks
 
I remember one of Jerry Busse's earlier knives was like that, I am not sure on the coating but I would go for the edm to do the pattern.
 
here is what i have come up with. it is not as deep as it looks and is very smooth and not rough. i like it but i thought i see what you think.

flintterxture.jpg
 
It looks good but not like chipped stone to me. Obsidian an flint look more like flats at different angles to me. But my memory could be screwed up cause I'm exhausted.
 
Ya I'm excited to play with it, i just got an air compressor to run it. I have had it for awhile but just not had the air to power it.
 
I use a 1/4" carbide ball burr and a 1/4HP flexshaft to do that. I handle them in stag, just like the photo.
Here is a basic build:
Start with 1/4" steel. I have done most of this type in BG-42 and ATS-34, but carbon steels like O-1 and 108X will work fine.
Shape the blade to its basic profile by forging or grinding. Make it a bit thicker than the desired finished blade. Grind in a convex bevel, leaving the edge about .100 thick. Using a sharpie or Dychem, black out the blade areas that are to knapped (carved in a chip fashion). Start at the edge and make sweeping cuts with the burr, creating a rough serrated edge. Do the edge from both sides. Proceed up the blade toward the spine, overlapping the cuts in a more or less random placement ( avoid neat rows). No need to do it all in one pass. Go back and deepen the "knapps" randomly, to create more variety in the texture.I prefer to flip from side to side as I work, to keep the pattern more even . It will take about an hour to knapp out a 3-5" blade. At this point it will look pretty rough. Take a 1X1/4" medium Cratex wheel ,which you have rounded the edge on, and go over the whole thing again ( I often hit it with a fine toothed ball burr first ,to get the deepest grind marks out. A diamond ball burr does well here ,too.). This will smooth out the grind marks and allow you to adjust the knapps to look more like chips in stone. While using the cratex, take the edge down to a scalloped serrated edge. After both sides are done, clean up any other areas on the blade and stress relieve well before HT. After HT and temper, etch the blade briefly, then repeat the cratex grind, taking the edge down to almost sharp. It will make an amazingly sharp edge when those scallops are hollow ground by the small wheel. Once all looks good, etch again to darken the surface .Buff the blade well with black compound. When you are happy with the final surface, clean and etch the blade deeply. Give the edge its final touch up (the edge only) with a cratex wheel and blue if desired , or just give it a quick etch again (I like the dark grey color of the etched steel).

If you used carbon steel the blade will be dark grey or deep blue,depending on your etch/bluing treatment. If you used stainless steel, etching in muriatic acid will create a grey stone like surface. The advantage of the stainless steel is that there is little problem with taking the blade to almost sharp before HT. What goes into the HT foil is pretty much what comes out .

The only photo I could find of one I did is a really ugly one, but you will get the idea.

Stacy
 

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Hello:

Didn't Mr. Bill Cheatham down in Phoenix (I think) do this in his "chiopped flint" knives back in the 1980's or so. Maybe you shouild try to hunt him down (if he is still alive..I know he's a retired Phoenix Police Officer) I am sure he will tell you how he did it..

Jason
 
bladsmth said:
I use a 1/4" carbide ball burr and a 1/4HP flexshaft to do that. I handle them in stag, just like the photo.
Here is a basic build:
Start with 1/4" steel. I have done most of this type in BG-42 and ATS-34, but carbon steels like O-1 and 108X will work fine.
Shape the blade to its basic profile by forging or grinding. Make it a bit thicker than the desired finished blade. Grind in a convex bevel, leaving the edge about .100 thick. Using a sharpie or Dychem, black out the blade areas that are to knapped (carved in a chip fashion). Start at the edge and make sweeping cuts with the burr, creating a rough serrated edge. Do the edge from both sides. Proceed up the blade toward the spine, overlapping the cuts in a more or less random placement ( avoid neat rows). No need to do it all in one pass. Go back and deepen the "knapps" randomly, to create more variety in the texture.I prefer to flip from side to side as I work, to keep the pattern more even . It will take about an hour to knapp out a 3-5" blade. At this point it will look pretty rough. Take a 1X1/4" medium Cratex wheel ,which you have rounded the edge on, and go over the whole thing again ( I often hit it with a fine toothed ball burr first ,to get the deepest grind marks out. A diamond ball burr does well here ,too.). This will smooth out the grind marks and allow you to adjust the knapps to look more like chips in stone. While using the cratex, take the edge down to a scalloped serrated edge. After both sides are done, clean up any other areas on the blade and stress relieve well before HT. After HT and temper, etch the blade briefly, then repeat the cratex grind, taking the edge down to almost sharp. It will make an amazingly sharp edge when those scallops are hollow ground by the small wheel. Once all looks good, etch again to darken the surface .Buff the blade well with black compound. When you are happy with the final surface, clean and etch the blade deeply. Give the edge its final touch up (the edge only) with a cratex wheel and blue if desired , or just give it a quick etch again (I like the dark grey color of the etched steel).

If you used carbon steel the blade will be dark grey or deep blue,depending on your etch/bluing treatment. If you used stainless steel, etching in muriatic acid will create a grey stone like surface. The advantage of the stainless steel is that there is little problem with taking the blade to almost sharp before HT. What goes into the HT foil is pretty much what comes out .

The only photo I could find of one I did is a really ugly one, but you will get the idea.

Stacy
Click to expand...

hay Stacy,
is it possible to find a 1/4 ball diamond burr with a 1/16" shaft. my dremmel tool is on the fritz so i only have the air tool right now.
 
There was a fellow at the Oregon Show about 10 years ago that was doing that look just by using the edge of his contact wheel.
 
Probably not, and probably a good thing. At the speeds of an air grinder, the tiniest bit of out of round will break the shaft and send a missile across the room (hopefully with nothing fleshy in the way). With a 1/16 shaft and a 1/4 ball, the 4:1 ratio is huge,easily bending the shank, and thus being unsafe.
However, a flame burr might work OK.

The biggest problem is that 1/16" air grinders are fine work tools ,and not for hogging steel. Far better to get a flexshaft (a dremel won't hold up to that kind of use, probably).
Send me an email and I'll see about fixing you up with a Fordom unit and handpieces.

Stacy

Note to all:
NEVER USE AN AIR GRINDER,OR OTHER HIGH SPEED HANDPIECE, WITHOUT SAFETY GLASSES OR A FACE SHIELD !
Better you never experience the thrill and excitement of something coming off at 400,000 RPM, but if you do, there has to be something very shock resistant between your eyes and the handpiece. This isn't one of those " We all learn by our mistakes.." things that some chaps love to spout when caution is advised. The learning curve here can go from zero problems to zero vision in about .001 second. I know I am always giving stern safety advise, but this is one of those things where you best trust me.
 
Don Fogg once hosted a tutorial from a knife maker from Argentina , that gave a step by step with pictures that was real good , but I no longer have the link . Maybe he has a link on his web site , or someone else may have the link . I think he called it a stone knife , but it was made out of metal .
 
I can rememeber when Blade Magazine did a article on Mr. Bill Cheatham years ago.They also showed how he did his tecnique of carving the chipped blade.He used a cut off wheel in a dremal and cut gouges out of the steel to resembel the chipping on flint.It looked really cool.I did some back then but dont have any pictures.
Bruce
 
This was my attempt at an obsidian look. I didn't spend as much time on this piece as I had wanted, but have had people see it and instantly say "wow is that made out of obsidian". So I guess it fooled a few.

I have went further - actually have a test plate with different attempts need to get a picture of it.

DSCN7624.jpg
[/IMG]
DSCN7642.jpg


Let me know what ya think.
 
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JT Sure would like to see a pic of your knapped steel blued. After looking at it again it really does look like a carefully knapped flint or obsidian tool. To where mine looks maybe more like obsidian in a natural form.
 
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