robgraham wrote:
On 29 May, 15:41, dg wrote:
Apart from reasons of practicality, is there any reason for not using
coach screws instead of coach bolts for fixing large timber sections -
ie is the strength and longetivity of the fixing the same?

dg

For a start lets do the pedant thing and at least get them called by
their right names - they are "coach bolts" and "carriage screws".

The argument on sheer and tensile is cobblers as diameter for diameter
the sheer strength is going to be the same.

This is not the case. The key difference is that the valley of the
screw threads concentrate the sheer forces on the metal at the bottom
of the vally on the loaded side. With a plain shanked bolt this
concentration does not happen and the load is distributed over a
larger area.

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd