Pressure flaking 101

[iowabow]

I only learned this in June so I am really not great at it but will try to explain so you might understand.  I am going to take a group of photos to show you how I set things up.  My technique is just a little different than Shannon's because I can't make my hands bend just like his so you will have to adapt this technique to what works for you.  There are many ways to pressure flake so please read this as an option to not a how to.  This post is for those of you that can make a biface but are now having trouble switching to the pressure flaker for the more delicate work.
I generally use three techniques to approach pressure flaking. 
1.  Shearing which I use to shape and set platforms.  If I am just shaping I also want to do it so I have the platform on an advantageous side for my next pass.
2.  Short flakes- They are used for establishing convexity, to prevent steps near a concavity, and for running thin narrow flakes up to center.  The short flake technique is accomplished by pushing down a lot more than in. 
3. Longer thinning flakes are for reducing the thickness and thinning the edge.  This flake poses the greatest risk for over shot that results in nipping off the opposite side. 
So I will shoot a couple of still shots to illustrate the above three and will attempt to video tape how I do each of the three.

[iowabow]

These three photos are of shearing the first two are how I hold and the third is what the surface looks like after.

[iowabow]

Now the short flakes.  My son did not take steady photos but that is not important but cause what you need to be focused on is the angle of the tool to the bi-face.  The angle is sharper with the shorter flakes.  In the second photo I moved my hand so that you can see that I get power from my knee so that my wrist don't wear out. Also note that my left hand is supported by the left knee.

[iowabow]

This group shows how we take advantage of the ridge to thin.   Note that we have good convexity and that the two previous flakes broke past center and even undercut an earilier hinge due to good convexity.  Note the angle it is more inward than the short flake but it not inline with the convexity slope (the angle of the flake you are removing).  Holding the point  with your left hand will be covered tomorrow.  The movie will be made tomorrow. Also note that the right hand should be on the right knee like in the photos above.  This is real basic because I swicth it up so much.

[iowabow]

I thought I would say a little about the difference between the leather pad and a notched rubber pad. I use both but for different reasons.  I can tell you that the rubber pad works good but the leather works great! The reasons are many but the main and basic reason is that the tool stays with the flake longer and as a result drives the flake off without breaking.  This is because they flake is not allowed to flex as much because the point is against the leather.  Adjusting the pressure of your left fingers on the point  changes where the flake stops in relationship to the angle and pressure of the tool that is held in the right hand.

[Lee Slikkers]

This is perfect timing!  I spent the better part of my afternoon destroying some fairly decent rock    I still don't have very good luck at making preforms either but I was really struggling trying to make some long flakes and driving them past center.  Looking forward to the vid!

[bowtarist]

I've been in a droll for about 10 days now.  Busted several preforms, several near finished points, and am nearly out of stone.  I have had some luck on getting to biface and preform, so I have five or so to work with.  My dial-up connection wouldn't load all your shots.  I think right now my biggest deal is I haven't seen anyone set up a platform or abrade an edge.  I just do whatever feels right at the time and lately it's ended in disaster.  Anywho, I'll try to check you out on a faster connection, but I think I'll head outside right now for a bit anyway. 

Take are and thanks, dpg

[iowabow]

shearing flakes video
http://www.youtube.com/watch?v=QZu-e2QSCZk
short flake (establishing convexity) video *Note at the end of the video I say that shearing created shorter flakes than the short flake process which is true but the shearing was done to the other side in order to setup the platform.
http://www.youtube.com/watch?v=vt5wyP1eONI

[iowabow]

The thinning flake video will be posted tomorrow because I did not have time to make it today. The process is going to be similar to short flake removal but will involve inward pressure and an angle change. I will also need to make a video about how to hold the point in the left hand because it is the other 50% of what is going on. When Shannon showed me this to me this summer it was very hard to do because I was not use to working the stone with both hands at the same time. It took me about 60 days to figure all of this out. I am still learning. Sawfiler and Jeff helped me learn this at Twin Oaks during the IBO this summer. If you have not been you should plan a trip to meet some of these amazing flint knapper in TN.

[iowabow]

If you are new to pressure flaking I recomend that you use scrap flint to practace these techniques on. It will take a few week to develop the muscle memory and achive skilled flake removal. Anyway are the videos helpful?

[Gus]

Excellent Thread iowabow!!

Thank You for taking the time to put this together.

I'll be cutting out some leather padding this afternoon.

Just finished the Knapping chapter in TTBB Volume 3 (Scott Silsby)
He's using leather pads with a thumb hole cut in one end like an Artist's Pallet.
Looks like several loose layers of 3-4 or 4-5 oz. leather, cut to fit his hand.
It also looks like sometimes he uses 3, 4, or 5 layers at varying times and on varying
sizes or types of rock.

My pressure flaking is better than my percussion flaking...
but then again, that ain't saying much at this point in my rock crushing newness.

Rock On!   

-Gus

[iowabow]

Just shot the thinning flake video and it will be uploaded tomorrow morning at 8:10am.  It is good and should help those that need help.  I want to say again that just because you see it done does not mean it will be easy to do well without lots of practice.  When I watched a demo  I thought ok that will be easy but it took lots of practice.

[gstoneberg]

Thanks John, I really need this.  Unfortunately, every second of my time now is used to prepare for the deer opener Saturday.  Not sure I'll break any rock now until Sunday.  I for sure will try it all out then.

Thanks,
George

[iowabow]

Np G the post will be here a long time.  I am going to post two more real basic videos. I know these are not the best videos but maybe they will help someone.

[iowabow]

Trouble uploading new video i will have it up when i work out the bug.