Make a set of mill stones - PEM BB traditional.straw.millstones

This is a badge bit (BB) that is part of the PEM curriculum.  Completing this BB is part of getting the Straw badge in Traditional Skills.

Everyone likes bread and circuses, but how do you turn wheat into flour?  Let's make millstones for a small grist mill!

 
 

Here's one way to do it:


Minimum requirements:
  - Make a set of mill stones for grain
  - Stone grinding surfaces
  - Curved spiral grooves in both stones (one curves left, the other right)
  - This bb can only use materials that existed 200 years ago

Provide proof of the following as pictures or video (<2 min):
  - The stones you're starting with
  - Several views of the stones getting shaped
  - Finished mill stones