Unfold cylinder

Hello everyone, I would like to unfold a sheet metal cylinder with an outer radius of 3000 ep 2
using the K factor for unfolding, the problem is that having fixed the K factor at the minimum, (0.01) I am always too long, (test done on a rolling machine) whatever, does anyone have an idea. Thank you for your answers, I'll put a screenshot
Capture d’écran (64)
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Marco.