Abstract: An open triangle made of rigid material planes each joined ninety degrees to one another and of sufficient thickness, rigidity, precision and construction for the triangle as a whole to serve as a brace for clamping, aligning, and joining workpieces, especially three workpieces at ninety degrees to one another; the opening of the triangular brace serving as a space for the operation of joining the workpieces, especially joining by means of high-heat welding but also by other means of joining, like drilling and fastening with bolts; the triangular brace being constructed of one piece, or a plurality of pieces in which one plane or all planes of the brace are removable and re-attachable, or rotatable in and out of position, by means of screws, bolts, pins, interlocking tongue-and-groove, magnets, axle for rotation, or other secure means.

Abstract: An open triangle made of rigid material planes each joined ninety degrees to one another and of sufficient thickness, rigidity, precision and construction for the triangle as a whole to serve as a brace for clamping, aligning, and joining workpieces, especially three workpieces at ninety degrees to one another; the opening of the triangular brace serving as a space for the operation of joining the workpieces, especially joining by means of high-heat welding but also by other means of joining, like drilling and fastening with bolts; the triangular brace being constructed of one piece, or a plurality of pieces in which one plane or all planes of the said brace are removable and re-attachable, or rotatable in and out of position, by means of screws, bolts, pins, interlocking tongue-and-groove, magnets, axle for rotation, or other secure means.