Author Topic: slab preform  (Read 3603 times)

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Offline 1442

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slab preform
« on: September 28, 2015, 01:59:17 pm »
I've traded a few slab preforms lately and want to show how I work them.
I haven't knapped in a while and I made a lot of mistakes here but am gonna post it anyway as a starter, and make a better one incorporating all the things that I neglected to do on this one.
Here's the preform.
Raw gravel 1/4" thick
then the first flake

Offline 1442

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Re: slab preform
« Reply #1 on: September 28, 2015, 02:03:42 pm »
This is the first pass of flakes down each margin. I work from the tip and alternate flakes from each margin on same side of point. The edge after first pass and the edge after nibbling off all the deltas. I should have nibbled the deltas as I went like I will show on the second pass but this works.

Offline 1442

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Re: slab preform
« Reply #2 on: September 28, 2015, 02:09:24 pm »
second pass, still alternating from each margin on same side. thebottom edge of the second photo is how the margin looks when the deltas are nibbled off as I go, then the second pass on the second side.

Offline 1442

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Re: slab preform
« Reply #3 on: September 28, 2015, 02:13:09 pm »
This is the margin after two passes on each side. I should have been working around the base each pass, but now I wound up with a stack on one side. take an x-ray.

Offline 1442

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Re: slab preform
« Reply #4 on: September 28, 2015, 02:16:18 pm »
OK! I sheared off an entire corner with a flake somehow :(
just have to work the base shorter and remove that stack while I'm at it.

Offline 1442

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Re: slab preform
« Reply #5 on: September 28, 2015, 02:25:16 pm »
notched it but sheared off the corners and didn't like the notches so I converted it to a stemmed point. Turned out 15/16" wide and weighs 70 grains.

Offline Knapper

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Re: slab preform
« Reply #6 on: September 28, 2015, 02:40:17 pm »
That's how ya do it 1442
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Offline mullet

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Re: slab preform
« Reply #7 on: September 28, 2015, 04:44:56 pm »
Nice point, Slab Knappers Unite!
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Offline Dalton Knapper

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Re: slab preform
« Reply #8 on: September 28, 2015, 05:45:30 pm »
You did two major things right that if not done, make slab points look like points made from slabs. Nice tutorial too!

1. You made the point pointed. Lots of slab knappers, especially if they start with a rectangular slab, wind up with a parallel sided point that tapers just at the tip, making for a bullet shaped point with parallel sides. You had a tapered slab to begin with (smart), but kept the triangular shape well. Most real world points begin their taper to the tip somewhere on the base or lower 1/3rd and may taper in (or expand) towards the base too - it varies of course according to point style.

2, You didn't skip from the first row of flakes to the last row of flakes too quickly so you got a very natural looking lens-shaped cross section and if you laid it down, it could be wobbled from side to side as well as end to tip. Lots of slab knappers don't get a true lens shape and if you laid their point down, the flatness of it would be very apparent. A flat point just doesn't look natural.

In short, you got a beautiful, natural looking point from a slab. Great job. I just hate points that look like a rounded, flat slab with a point on the very tip.

Offline Tracker0721

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Re: slab preform
« Reply #9 on: September 28, 2015, 10:02:47 pm »
That is a good looking point! I have a couple slabs I wanna try but they are crazy sizes and shapes so I'd need to cut em into manageable pieces- way too much work. Just gonna stick to tried and true Bop and pray
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Offline jeffp51

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Re: slab preform
« Reply #10 on: September 28, 2015, 10:35:53 pm »
Nice. What are you using as a flaker? If it's copper, how big?

Offline 1442

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Re: slab preform
« Reply #11 on: September 29, 2015, 02:45:08 am »
Thanks y'all,
Jeff, I'm using copper ground wire about 3/16" diameter in a delrin ishi stick and don't really keep it sharp, but I file it enough to keep off the burs and maintain the size of the end at about 1/16" ,I guess, then will use it till it gets pretty rounded or gets a burr, then file again.
I did another one tonight, and took pics, but left the camera so I'll have to post it later.
I broke a 1/2" off the tip and had to remodel it, but it came out exactly 70 grains like this one but it's 1" wide .