Abstract: A guide to be clamped on a door or similar object to guide a portable circular saw to insure accurate cuts. The guide has an elongated, rigid member having a block pivotally attached at one end. The object to be cut with the saw is clamped between that block and a second pivoting block slidably secured to the member. An eccentric device including a cam cooperates with a lost motion coupling for the second block to permit rapid initial installation of the guide followed by an increase in the clamping force to secure the guide in place. An elongated rib on the guide serves to stabilize the saw as the cut is made and the saw base slides along a planar portion of the guide member protecting the object from damage during the sawing operation.