Screw-Flight / Auger Flat-Pattern Developer

How it works: one turn of each flight edge is treated as a helix. Its length is √((πD)² + pitch²). The two helical lengths become the outer and inner arcs of an annular-sector blank whose radial width equals half the difference between flight and shaft diameters.

Print at 100%, verify the calibration mark, cut the sector, then form it to one pitch around the shaft.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Flight outside diameter

300 mm

Shaft / inside diameter

100 mm

Axial pitch per turn

250 mm

Extra outer-arc allowance

0 mm

Primary result: Blank outside radius: 170.00 mm.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

A screw flight is a helicoid, which is not an exactly developable surface. This is the established annular-sector workshop approximation and forming, springback, material thickness and welding can change the finished dimensions. Make a test piece before production.

The optional allowance extends the sector angle at the outer radius; it is not a radial edge, root gap or thickness compensation.