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Central Ridge
Ahnlaashock:
I have been practicing on decent sized flakes, which often have a central ridge right in the best part of the flake. In my latest attempt, I prepared a platform like I was fluting it, and I drove a flake all the way to the tip, right down the ridge. I was quite pleased.
This created two ridges, so I tried to do it again, down the higher of the two. Naturally, it ran for about an inch, and then hinged out when it hit thicker material. No biggy. I thought, neither one is too high, and I should be able to get them from the side.
No such luck. The lower of the two seemed to be an excuse for flakes to hinge out, and by the time I got past it, with a hammer stone, I had a center ridge again. I actually got disgusted and used a high margin flake with the long flaker, to rip out a big chunk from each side near the tip, figuring if I could break the ridge, that I could then take it off a piece at a time. Nice deep flakes that run right to the top of the ridge, which is now steeper than it was.
How do you deal with center ridges? Thanks in advance!
Outbackbob48:
First off I am not an expert. When I have a central ridge and not a lot of width I set it up just like you did an take a flake down the center. If this stacks some times you can come from the other end. With no pictures i can only guess at what happened when you went down your second ridge, I'm quessing but probably hit it with less force an stacked. As far as coming from the side on the third ridge I'm guessing that it was slightly concave from side to ridge an this will create stacks. Remember with out pics I am just visually guessing at the problems. Hope this may help. As far as recreating a center ridge I would say your thinning flakes are not going past center from each side there fore creating a ridge, need to get your flakes to travel past halfway in order to thin. Hope this helps and is not to confusing. Get to a knapin an some one can help ya better than explaining.
JackCrafty:
Central ridges are good. I like them. If you mean "How do you NOT end up with a central ridge", well... that's tricky. Especially for beginners.
The easiest way is to start with a thin flake to begin with, with a ridge that is not down the center. A ridge on the side is easier to remove than one in the center. You can make this happen by trimming one margin back so that one edge is close to the ridge. Now, flakes don't have to run as far to remove the ridge.
seminolewind:
I don't mind center ridges but don't really care for triangular spalls. I will say from my limited experience if you are going to drive a flake from the base to the tip (same direction as fluting) do so when the spall or flake is at its thickest. If you wait till its worked down thinner the shock from the percussion usually will break the point right in the middle.
Ahnlaashock:
I never got a flake to cut the ridge, to have to recreate it. I just ended up removing so much of one edge, as to move it back to the middle.
Good read on what I was working with Bob. You pretty much nailed it. If I had been able to get a flake to cut through the ridge, I could have removed it. That is why I used the long flaker and high platforms, trying to break it, or at least weaken it, so I could break it from the other side. By the time I had corrected the line of steps, that ridge had been dealt with by basically eliminating everything on that side of it. before I was done, I ripped out thee millimeter deep high platforms to try to force a flake to go on through it, after using up the width trying other methods.
I did do the thinning flake from the base while the flake was still as thick as it started. The only thing I removed before that was the thin edges. I took it out and used a brass billet to do the percussion outdoors. It was too cold to play out there long, so I wasted the rest of the flake trying to find a way to flatten the one side, using pressure. Nothing I tried would let me deal with the ridge. I would have been better off to have beveled the flat side to a center ridge, and accepted the diamond profile.
Maybe indirect would have allowed me to cut through it.
On the basal thinning flakes, I tend to fold a piece of soft rolled up leather in half, and then hold the point between the sides where it is supported and cushioned full length. I have not broken one yet, but I am sure I will sooner or later. I have broken them every other way. It isn't like I am getting anything thin yet.
I guess I am going to have to use percussion to get closer than I have been before going to pressure.
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