Instructions for Making Ishi Sticks and/or Pressure Flakers

by James C. Keffer

Materials - Tip

1. 1/4" C110 (full hard temper) copper rod (available at OnLineMetals.com)
2. 99.9% copper
3. Tensile Strength - 50,000
4. Yield Strength - 45,000 Rockwell hardness - B50
5. Copper Rod - twisted to further work harden. 
6. ¼" set screw (Allen screw - coarse thread #20)

• Material - Handles
  1. Acetal plastic (Delrin brand name), 3/4" diameter round bar, 16" - 20" length for Ishi sticks, 5" - 6" for pressure flakers (also available at OnLineMetals.com)
  2. Drill (1/2" or real strong 3/8")
  3. #7 or #8 drill bit
  4. Vice
  5. Hammer and anvil

Instructions:

Pressure flakers and Ishi sticks are two of the easiest and most effective flintknapping tools one can make. 

1.     Start with a 12” length of 1/4" C110 Full Hard Temper copper rod.  Put one end of the rod in a vice and the other in a 1/2" drill and slowly twist the rod to work harden. I twist the rod 40 revolutions, more than than may cause it to break unpredictably (a sharpie mark on the drill chuck makes counting the revolutions easy).  Twist slowly and covef with a wet cool rag so as not to over heat the rod.  This makes the copper rod about 3 times as hard thus less likely to bend or deform. 

2.     Next the tips are further hardened by hammering into a 4-sided point. Point should be no more than 1” in length

3.     Cut the acetal plastic round bar to length. For Ishi Sticks use a 16” – 20” length of ¾” diameter Delrin round rod, for pressure flakers, 5” – 6”. 

4.     Drill a ¼” diameter hole down to a depth of 4” in one end to receive the copper tip.  The same works for both the Ishi stick and pressure flaker.

5.     Drill a hole ¾” from the tip end using a # 7 or #8 drill bit to receive the set screw.

6.     You can either use a ¼” tap or the set screw itself to cut the threads for the set screw (tap is easier but it can be accomplished with the set screw).  The set screw serves two purposes – it allows the tip to be replaced when worn out and keeps the tip from turning or twisting under pressure.

7.   The ends of the acetal plastic rod may be rounded or tapered and smoothed with any number of tools, from files to sandpaper.  I found that a 6" grinder with one fine grinding wheel and one cloth buffing wheel works great.  The cloth buffing wheel will both remove material and leave a smooth, shiny finish on the ends.