Sheet Metal & HVAC Unfolding

When bending a 4-flange sheet metal pan or electronics chassis on a CNC press brake, the outer fibers stretch while the inner fibers compress along a neutral axis governed by the material's K-Factor (typically K = 0.42 for mild steel and aluminum in air bending). If you do not subtract the Bend Deduction (BD) from each flange or omit corner bend relief notches, the metal tears at the corners and finishes oversized. Our parametric unfolder calculates exact DIN 6935 90-degree bend allowances and places square corner relief cutouts for fiber laser, plasma, or waterjet cutting.

Fabricating a structural sheet metal U-channel, servo bracket, or clevis mount requires subtracting two 90-degree Bend Deductions (BD) from the total flat blank width so the bent side legs finish at exact parallel spacing (L). Our parametric U-bracket unfolder applies DIN 6935 neutral-axis K-Factor math (K = 0.42), chamfers all four outer mounting corners for deburred safety, places 6 precision closed bolt holes across the web and side legs, and isolates the two press-brake bend lines on the BLUE CREASE layer.

Unfolding a sheet metal HVAC duct reducer, exhaust hood, or pyramidal hopper transition requires true-length 3D triangulation because the vertical elevation height (H) is shorter than the true sloped slant height of the four trapezoidal facets. Our parametric sheet metal unfolder computes the exact true slant height (S_true = sqrt(H² + ((D_bottom - D_top)/2)²)), develops all four contiguous trapezoidal facets into a single radial flat pattern with a Pittsburgh/spot-weld lock seam allowance, and adds top and bottom flanged attachment collars.

Structural 90-degree corner gusset plates—used to brace welded steel tube frames, CNC machine gantries, and 2020/3030/4040 T-slot aluminum extrusions—require an inner apex relief chamfer so the plate sits flush past the weld bead or corner fillet, plus accurately pitched bolt hole arrays along both orthogonal legs. Our parametric corner gusset generator builds a symmetric or asymmetric right-angle triangle plate (`L × W`) with a clipped inner weld-relief chamfer, truncated safety tips on the outer corners, and 5 precision bolt holes (`Ø = H`) aligned along both structural axes.