An apparatus for cutting a workpiece, the apparatus having a pair of spaced apart rails fixed to a handle, the rails extending away from the handle in a first direction, a guide carriage slidingly engaged with the rails, a blade carriage slidingly engaged with the rails between the handle and the guide carriage, a pair of runners for supporting the workpiece, one of the runners joined with the handle and a second one of the runners joined with the guide carriage, the runners extensive in a second direction non-parallel to the first direction, and a cutting blade engaged with the blade carriage in a position for cutting into the workpiece during relative movement between the apparatus and the workpiece. With the guide carriage adjusted for receiving the workpiece on the runners between the guide carriage and the handle, the blade carriage is adjusted to a location for severing the workpiece.