Tapping a thread in resin

[huldah]

Depending on the application, a rivnut might be more reliable than a tapped thread but, for high loads, I'd agree with those who suggest casting a nut in place.

I've never needed to do it, but I think plan A would be to grease a bolt, thread the nut on it and cast the whole lot in position. Once the resin's gone off, unscrew the bolt.

When the resin has set there is zero clearance between the bolt and the resin which can lead to difficulty. One way round this is to stretch TPFE tape round the thread.

 

[Seatrout]

I recently tried 'chemical metal' on an exhaust elbow where the thermostat housing adjoins. The tapping was unsuccessful, and a drill-out and installation of a hell-coil did the trick. OTOH, the chemical metal repaired a crack on the elbow with great results.

 

[aquaholic]

Thanks for all the response and sorry for not replying sooner. The threaded part of the screw is a support for a hand rail and have decided to drill out the hole and use bridger compound which is an epoxy paste with fibreglass strands. Have packed the hole out and screwed the thread into it and will leave it to set for a few days and will see if it is man enough. Will post back with results.