Abstract: A clamp for holding lumber which is used to form roof trusses. A plurality of clamps are placed on a work table oriented to constrain plural pieces of lumber forming the truss until truss plates attach ends of adjacent pieces of lumber. The clamp includes an inner and outer sleeve, the inner sleeve telescopes with respect to the outer sleeve and a spring bias connection exists between the inner and outer sleeve through a threaded shaft which causes the inner sleeve to telescope so that imperfections in the lumber can be accounted for and several identically configured trusses can be formed without removing the clamps from the table. Specific types of clamp support for the lumber as well as a specific means for supporting the clamp on the work table is disclosed.