Expandable frame for silk screen

Claim 1

AN EXPANDABLE FRAME FOR STRETCHING SHEET MATERIAL COMPRISING: A PLURALITY OF FRAME MEMBERS HAVING GENERALLY RECTANGULAR CROSS SECTIONS HELD TOGETHER IN ENDTO-END RELATIONSHIP BY CORNER GUIDE BRACKETS; EACH OF SAID FRAME MEMBERS BEING FORMED WITH A GROOVE ON ONE SIDE AND EXTENDING LENGTHWISE THEREOF, THE CROSS SECTION OF SAID GROOVE HAVING AN INTERIOR DIMENSION PERPENDICULAR TO THE LENGTH THEREOF AND PARALLEL TO SAID SHEET MATERIAL IN EXCESS OF THE SIMILAR EXTERIOR DIMENSION THEREOF, SAID EXCESS LYING ENTIRELY ON THE SIDE OF SAID GROOVE NEAREST THE INSIDE OF SAID FRAME; A LOCKING STRIP IN SAID GROOVE, SAID LOCKING STRIP HAVING A CROSS SECTION SIMILAR TO THE CROSS SECTION OF SAID GROOVE; SAID CORNER GUIDE BRACKETS HAVING A BOTTOM AND UPSTANDING SIDES THAT DEFINE A PAIR OF CONVERGENT U-SHAPED PASSAGES WHICH RECEIVE THE ENDS OF TWO FRAME MEMBERS, RESPECTIVELY, IN SLIDABLE RELATIONSHIP; SAID FRAME MEMBER BEING ORIENTED SUCH THAT SAID GROOVE IS LOCATED ON THE TOPSIDE OF SAID FRAME; A MOVABLE ABUTMENT DISPOSED AT THE INTERSECTION OF EACH PAIR OF SAID CONVERGENT U-SHAPED PASSAGES, SAID ABUTMENT HAVING A PAIR OF CONTACT SURFACES FOR SIMULTANEOUSLY ENGAGING THE ENDS OF SAID FRAME MEMBERS; AND MEANS FOR INDEPENDENTLY MOVING EACH OF SAID ABUTMENTS IN A DIRECTION TRANSVERSE TOP THE U-SHAPED PASSAGES OF ITS CORNER BRACKET, THEREBY ADJUSTING THE POSITION OF SAID ABUTMENT AND SLIDABLY MOVING SAID FRAME MEMBER ALONG ITS ASSOCIATED U-SHAPED PASSAGE.