From DT Online
The edges of thin sheet metals can be extremely sharp and dangerous, especially when cut, so often need to be made 'safe'. The simplest way to achieve this is to fold the metal over on itself along the edge. This is known as making a Safe Edge (or Hem).
Making the Joint
- Mark out the width of the Hem.
- Fold initially to an acute angle using Folding Bars and Hatchet Stake or Bench Folder.
- Use a Boxwood or Rawhide Mallet to beat it flat down on to a Bench Block or similar surface.