How this calculator works
The FAA sheet-metal rule uses about three times the thickest sheet for rivet diameter. A further 1.5 diameters of shank is allowed to form the shop head. The chosen increment rounds diameter upward; it does not certify an available stock size. This is not a boiler-joint design method.
Formula
minimum d = 3 x thickest sheet; selected d = increment x ceil(minimum d/increment); forming allowance = 1.5d; shank length = grip + 1.5d; hole = d + supplied clearance.
Worked example
For 1 mm thickest sheet, 3 mm grip and 1 mm diameter increments, selected d is 3 mm. Shop-head allowance is 4.5 mm and shank length is 7.5 mm.
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Frequently asked questions
Does head type change the shop-head allowance?
The allowance forms the opposite shop head. A countersunk manufactured head changes the catalogue length reference and needs its actual head height.
Can I use this for blind rivets?
No. Select blind rivets by the manufacturer grip range and hole specification.
Is hole clearance a universal constant?
No. Enter the clearance required by the rivet manufacturer and installation method.