Corner Cramp
From DT Online
Corner Cramps, or Mitre Clamps, are used to hold together right-angled frames or carcases as they are glued.
Band Clamps, or Picture Framing Clamps, employ a strap or just string to hold together frames.
Notes: Band Clamps are also useful for holding together round or irregular objects. Corners can be glued with a G Cramp if temporary blocks are first glued in position as shown - and planed off afterwards.