Countersink or Try to Dimple .040 4130 Steel?

[David Paule]

On my RV-3B, there's a 4130 flange inside a rib and skin. The rib and skin will be dimpled; they're too thin.

So should I try to dimple the steel flange, or try to countersink it? At .040, it's probably thick enough.

Thanks!

Dave

[Mike H]

I would countersink it. Use a lower speed than you would with aluminum and some lube.

[ppilotmike]

Yup. Countersinking this would be the way to go, since the flange is 0.040. If it was a little thinner, I might dimple. It sounds as though you have enough "meat" so I see know problem with countersinking.