Complex sentence: If the saw began closing, it could cause the saw to bind and increase friction; wedges, most often made of convenient bits of wood, could be inserted in order to keep the kerf open and reduce the friction.
Split into simpler sentences: If the saw begins closing, it can cause the saw to bind and increase friction. Wedges, most often made of convenient bits of wood, could be inserted in order to keep the kerf open and reduce the friction.