Abstract: Clamping apparatus for holding a workpiece such as a log comprises a cruciform support frame of legs the upper limbs of which define upwardly open V-shape volumes for receiving a log. Arcuately clamped arms are pivotally connected to respective legs and spring biased to a closure position by springs joined by chains to a rigid connector link pivoted to the clamp arm by a pivot projecting onto the opposite side of the clamp arm from the pivotal connection by which it is connected to the leg frame allowing it to be moved to an over-center cocked position in which a curved tail portion projects into the V-shape volume to act as a trigger initiating closure of the clamp arm with the log is placed in position.In other embodiments a flat working surface replaces the diverging support arms.