Steve, You know I'm not an expert, but it sound like you aren't "pushing/pulling" at just the correct angle. I push the flaker straight in and then try to push/pull it off at close to 90 degrees to the flat plane of the rock, grabbing the flake as I go. That is probably really confusing, but it's the best I can offer.
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I just have not done enough to explain it better. Fact is that may only be what I THINK I am doing. Have you heat treated the rock you are working? I'm glad i picked up one of those buckets of spalls, I know I won't be able to work anything bigger for a while any way, and I bet I'd make a whole lot of unusable junk working down a big piece. Plus it is a really nice variety.
Roger, It's a shame a "Claude" does not come attached to one of those clubs. Now that would be a handy tool to have.
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Swamp