Thread tapping into fiberglass-best method?

[preserved_killick]

I've never been a fan of relying on screws into fiberglass, but I need to install a hatch fastener for my forward hatch, and there's no way to through-bolt:


What's the best way to get the fasteners to hold? Tap threads into the fiberglass?? I've only seen taps for machine bolts with tiny threads. Self tapping screws? Glue inserts?

Jeff

[Tim]

You can tap effectively into fiberglass for machine screws, and the result is much stronger than self-tapping screws. I tap all fastener holes, even when through-bolted. Use regular taps; if you're going into a blind hole, there are special taps with flat tips that work best without bottoming out too early.



To add strength, and if future removal isn't an issue, you could add some adhesive on the threads--adhesive caulk or epoxy. I am not sure this is necessary for what you are considering, and you'd only want to do this if could foresee no future need to remove the fasteners.

[tpl]

another way, is to glass on small wood blocks in the way of yr fittings.
we use plywood, with several layers of cloth epoxied over. Short fat self-tapping
screws go in very satisfactorily, and hold well. If fanatic, you could embed t-nuts.

[mitiempo]

I think I'd tap and wet the threads with epoxy before tightening down. If you have to remove it at any time just heat the machine screws a bit and they will lose their hold and come out easily.

[preserved_killick]

Thanks guys,

I've got the taps. I'll give it a test run on some junk fiberglass first. I might try just a dab of 4200 on the threads.