Abstract: End mounts (92, 94) of an attachment are connected to bed (14) and bending leaf (44) portions of a shet metal brake (10). A right angle outer corner (102) is formed where an upper edge surface 46 of the bending leaf (44) intersects a side surface (48) of the bending leaf (44). A bending member (90) extends between the end mounts (92, 94) and is mounted for pivotal movement between a start position and a forming position. The bending member (90) carries force applying surface means (38) which rests on an overhanging portion of a sheet metal member (42). The operator swings the bending member (90) downwardly and as the bending member (90) so moves, the force applying surface (38) bends the sheet metal member (42) down about the right angle corner (102). The end mounts (86, 88) are formed to include arcuate slots (104, 106) having geometric centers which coincide with the bending corner (102 ).