How do you handle big bumps and triangular shapes?

[magick.crow]

I have been working with stone for a few weeks but I have run into a problem.
All the videos are by these great 30+ flintknappers and what they START with always looks better than what I get so I never see how they would deal with these problems.
First problem, a triangular shaped cross section. How do you make it flat? For that matter how do you turn a turtle shaped stone into something flat on both sides (or at least arrow shaped)
Second problem is a lot like the first, a big bump in the middle of the stone where none of your flakes managed to reach and often with steps? Toss it out? Go for the super flake?
Thanks,
Douglas Knapp who seems to have acquired a bleeding disease.

[Zuma]

Yep with chunky stuff take the super flake.
But first make a proper platform.
Zuma
Show me a pic and I'll try to help ya.

[Stringman]

You're right this is a common problem that doesn't get addresses a lot in the vids. Simple answer is: raise your platform! Also, don't try to take it all in one blow. This approach usually leads to another step or causes other equally frustrating problems. Instead take a good flake then reset your platform and hit it again.

It is possible to work yourself into a corner and then not have a lot of options on how to deal with the issues you've created. That's why it is good practice to slow down and think about your approach. The military says, "slow is smooth-smooth is fast!" So when you first pick up a rock, plan your strategy based on the obvious ridges. Flakes like ridges and will run more efficiently than thru flats or concavities. Use a pencil and plan your attack. Show us what youve got and let's try to help you through this.

[magick.crow]

Stone porn
https://youtu.be/-xE69T15RTA

I made a vid because I am a 3d artist (freelance, if you need anything like that) and I know how hard it is to show a 3d shape with a few photos.

This is my current best potential. I would like this to turn into something nice.
My other problem stones have been reduced to crumbs as I decided that if they were not going to do what I wanted then I would experiment on them and learn so I can't post any really bad stone pics.

I think this stone is flint. It is from the shore of the baltic sea between Germany and Denmark.

Thanks for the help.

[magick.crow]

You're right this is a common problem that doesn't get addresses a lot in the vids. Simple answer is: raise your platform!

OK, just to be clear by raise your platform you mean make a bigger one or put another way strike farther from the edge or deeper into the stone.

Another question. There seems to be two factors the angle of the edge from 90 deg to about 0 and I am not sure what effect that has on the flake. Also is strike angle from straight down to almost edge on. Seems to me so far that both extremes result in crushing or breaking of the edge and a good big flake is a hit that is more down but somewhat into the stone edge.

You also have stones that are like this
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   \
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or like this
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        /
     /

seems like the top one is the right one to hit but what is you start with the other? OR how about when you have a big slab with two 90 degree angles?

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            |
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Also I have one stone that more or less looks like a peanut. How do you handle round stones? So far everywhere I have hit it has resulted in nothing happening.   

:-)

[mullet]

Claude VanOrder taught me to tackle the turtle back first by setting up larger platforms and hitting it so it crossed the ridge diagonally. Taking it slow and whittling it down as Scott describes.

[Ghost Knapper]

Here is how I would tackle the piece in the video. Note that I would be using a copper bopper (smallish medium one)



So the first flake. This is about 12.75 seconds into the video. I would remove this flake from this face using the existing edge/platform. I would then remove some short clean up flakes and then remove one to the right of this flake to remove the remaining cortex. (see note at bottom)

Secondly I would do the following:



First I would remove the red area by removing short flakes. The platform is the area in red while the flakes would be removed from the opposite side of the piece. This would create a continuous platform.

Abrade continuous Platform

Next I would remove the short flake outlined in blue. This will help isolate the existing ridge for the larger flake.

Abrade again

Then I would remove the larger flake outlined in blue.

Those two examples should dramatically reduce the "turtle back" shape and make it more manageable.

Note: I would only use this existing edge if I was using a copper bopper, I personally do not think antler would react well to the existing edge, and I personally do not have enough experience in other percussors to say how they may react.

[bubby]

I love watching videos of guys like claude van order chipping, there is an ease ro the way they knap , heck if I'm not knapping slabs i still struggle

[mullet]

Bubby, I've known Claude for over 30 years. he has been my biggest influence since I started. What is frustrating being around Claude is he can carry on a conversation , not really look at the rock and then it seems knapping is tooo easy. I really hated it when he moved from 20 minutes of my house to two hours away.

[Ncsnipe]

I would point you to a few YouTube videos to help you along. The first vids are by BOHUNTER, they are his problem rock series. There's a lot of great info in these vids. Pay close attention to his platform setup. The next couple of vids are by paleomanjim in his two sandwich knapping series. This technique really helped me remove across the middle and coast to coast thinning flakes. The final vids I would recommend to help you out are by our own JackCrafty. His vids seem to deal with small and irregular rocks often. Hope this helps.

[magick.crow]

Thanks for the video hints! I have watched some of Paleomanjim's stuff but not that one. I think it was his bopper video that lead to mine. (BTW the copper head is coming off, is this common?).
So I just made a new rock porn video so that Ghost Knapper can keep helping me. I was shocked that that first big flack worked perfectly. Honestly, I did not even see that point as a platform!

https://youtu.be/AcZiABWWeb4

[Ghost Knapper]

Can you post a picture of your tool/tools?

[Ghost Knapper]

So here is what I would do again with a smallish bopper.



Trim the edge to remove the red area to set up a platform.

Grind the platform.

Remove the flake outlined in blue.

If the strike angle is correct it should remove enough material to remove the "turtleback" shape and look like the "after" below.

[magick.crow]

So here is what I would do again with a smallish bopper.

Trim the edge to remove the red area to set up a platform.

Grind the platform.

Remove the flake outlined in blue.

How big is smallish?

If the strike angle is correct it should remove enough material to remove the "turtleback" shape and look like the "after" below.

What is the correct angle and why?
Thanks!
Douglas E Knapp

[Ghost Knapper]

Smallish is about this big (holds out fingers). 

The one I would probably use based on how the material looks has a head on it that is a 7/8 copper cap. I like to swing alittle faster with a lighter billet vs using a heavier billet. Now if the material is stubborn I would use a heavier billet.

The proper strike angle is a little more vague. If you have books or watch videos there are great illustrations on how the angle effects the outcome. If you strike to straight in it may hinge out or step fracture. Too vertical to the platform and the flake will fall short or may travel a nice distance but it wont remove much material. It will basically skim the surface of the piece.

Can you post a video or picture with your tools, I noticed in a previous post about the head coming off.

Also there is more than one way to skin a cat, so using antler billets, hammer stones, billiard balls, 30-06 etc. will also work but platform prep, strike angle and other factors may/will be different.