Work out shear force for cutting instantly with clear inputs, formula shown and shareable results.
Parallel blades cut the whole length at once, needing length x thickness x shear strength. A raked blade engages progressively, so only a short zone is being cut at any instant and force falls to t² x shear strength / (2 tan rake). That is why guillotines use a few degrees of rake and why the cut sheet acquires a slight twist.
Parallel blades
F = length x thickness x shear strength
Raked blade
F = t² x shear strength / (2 tan rake angle)
F = length x thickness x shear strength. Parallel blades cut the whole length at once, needing length x thickness x shear strength.
More rake cuts force but bows and twists the strip being cut off, and it lengthens the stroke. Two to three degrees is the usual compromise on sheet.
This calculator takes 4 inputs: Length of cut, Material thickness, Material shear strength, Blade rake angle. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.