I have gotten by for years with a few hammer stones consisting of oblong shaped fine grained igneous stones of a couple variety of sizes small to large for percussion flaking and whacking out spalls, and a section cut off a broom stick with a nail stuck in the end, and also the occasional sharpened deer antler tine as far as percussion flaking goes.
I learned to percussion flake as a teenager by dropping a 16 penny nail into dad's empty beer bottles, covering the opening with a finger, and shaking the bottle to drop the bottom out in a perfect clean circle...and then flaking it into little glass arrow heads (glass is the exact same chemical structure as obsidian, and similar enough to chert, flint, and the like in the sense that they all fracture concoidially with no planes of cleavage)... I did not learn to percussion flake until I was older and had access to a steady supply of flint.
As far as concoidial fracture goes though, that is the absolute essence of pressure and percussion flaking. It took me a while to be able to understand it, and begin taking out flakes in a puzzlelike pattern that contributes each flake to form a projectile point. But i will try to explain it the way i read when it finally clicked the first time for me.
First of all, shake a nail in a bottle with a flat bottom and let the bottom drop out onto a soft surface, and set it aside. you learn everything you need to know about percussion flaking by pressure flaking:
When pressure flaking, to understand concoidial fracture, visualize a bullet hole in a pane of glass. It has a cone-shaped exit hole, right? The entrance hole, however, is a clean hole of the exact size of the bullet. This is the essence, and when you understand it, move on to this sentence: In appying downward pressure with a pressure flaker to the top edge of a thin piece of flint at its very edge, then where the flake pops off, there is half of a cone-shaped indent taken out from the bottom side, across the bottom surface, and in the direction of the center of your pre-form... and that indent corresponds exactly to your flake that has just dropped off in your lap: Try it several times on the glass bottom and knap it down chip by chip confirming each time that this is true. Once you actually understand this paragraph and have flaked your first bottle bottom down to nothing and verified this statement holds true for most angles, verify the following on another bottom:
Changing the angle of your pressure changes the length of the cone,
Pressing very hard or very soft will result in very long, or very short cones.
Adjusting the width of your flaker tip results in larger or smaller flakes accordingly.
You cannot transfer a flake across an angle of less than 90 degrees.
This is all you need to know to make arrowheads out of a pre-form. Make a few out of glass bottoms now. They actually look pretty cool once they're done...
Now, everything I just said about pressure flaking is automatically true with percussion flaking...you only have to modify 3rd statement, which comes out to: switching to a smaller or larger hammer stone results in smaller or larger flakes as desired.
When learning to percussion flake, you will need a hefty supply of flint nodules to practice on using the same 4 statements as well as the description of concoidial fracture i gave. Also, now, instead of knapping a projectile point, you are knapping a pre-form roughly the same shape and size of a bottle bottom, at which point, you will switch to a pressure flaker and continue on to finish that pre-form into a projectile point. That will be the first time you have knapped a head from start to finish out of raw materials....
Steps of learning are
1) Mastering pressure flaking on beer bottle bottoms first, and finishing good arrowheads out of them until you can do it reliably (about a week).
2) mastering percussion flaking by trying to shape pre-forms out of raw materials (flint, chert, obsidian, agate, jasper, johnsonite). About a weekend...assuming you have several pounds of nodules
3) and finally, using your pressure flaking skills to knap one of your finished pre-forms into a finished projectile point. A couple hours.
By the time you have mastered steps 1-3, you will be able to start with a nodule of raw material, whack out several preforms, and pressure flake each one into a projectile point and end with several arrowheads. This is how you do it... get a nodule of raw material, whack as many pre-forms as you can out of it, thus keeping yourself supplied with pre-forms; and you knap on those individual pre-forms during your free time making heads to show off to your buddies...if you've ever met or talked to a knapper, he either is showing you a head out of his pocket that he is working on, or has already finished...and probably is about to drag you out to his truck to show you several good ones if you've taken the bait and shown interest.
-Hope this helps get you started!
