Spiral Screw Forming Development Formula

Helical screw design calculation1 1.Without mismatch by partial weldment and then follows the step 4.6 to 4.9.4.10 after completion of helicoidal screw forming make partial weldment into permanent weldment at joint area.Result: flight profile with welding as shown in fig.7.Spiral flight development varindo megatek.How to calculate.