The Klopfsäge mill was built in 1808 entirely from wood and stone. Iron was expensive so only used where necessary. it is in the Frond district of Holz and is the last of its kind in the Black Forest and now a museum. 

The term "Klopfsäge" (knock saw) is derived from a very simple functional principle of the saw powered by water power. The saw frame is lifted by a roller on the drive shaft of the water wheel In the highest position, the cam rotates away from the gate so that it falls down under its own weight and makes the saw cut.The falling gate is cushioned by a wooden pole, which gives the typical beating, knocking noise of the system. A part of the weight of the gate is taken up by a pair poles attached above it. The cutting process is repeated several times with each revolution of the mill wheel, depending on the number of cams, up to three can be attached.The trolley with the material to be sawn is usually moved forward by a pawl hat engages in a toothed wheel on the side of the trolley and is driven by the gate via a lever mechanism