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[Phys-l] stress in a wound (clock) spring

Occasionally a clock smith will repair a broken spring using rivets (scab on). I suspect the stored E is mainly shear (bending) instead of tension. Enormous, comparatively, force is necessary to stretch w/ such a large cross section of spring steel. Therefore, not much stress on the broken part . The rivets will be under mostly tension? Am I correct? The reason I ask is a poster on a clocks group thinks "this is a recipe for disaster". The energy stored is rather great, and when one goes, if not ina barrel, ruins the clock. Occasionally barrels are broken.


p.s. We'll possibly know as a Polish list member has done the repair using screws in a (rare?) multiple face clock (master w/ slave faces) being unable to find a replacement.