Tapping holes in phenolic sheet

[Tom Bain]

I mis-drilled some tap holes in phenolic sheet and now I need to fill those holes and drill and tap new ones just beside the old ones. I was thinking of using epoxy to fill, but that would mean the new tap threads would partially be in the epoxy. Any ideas or suggestions? I should add this isn't a high stress/load application.

-Tom

[Erik Loza]

Could you fill with JB Weld?

Erik

[Steve Demuth]

Epoxy bonds well to phenolic, and a filled epoxy, taps and machines well. But I've tapped other epoxies as well, so I think your solution will work fine.

[Richard Coers]

I'd make a plug of phenolic and epoxy that in the hole instead of just filling it with epoxy.

[Tom Bain]

Could you fill with JB Weld?

Erik

Possibly. It's not a large hole (10-24 tap) so not sure about how well the JB Weld would "flow" into hole.

[Jack Frederick]

Perhaps tap the current hole, then fill and re-drill. That provides a shoulder for the glue to bite into.

[Jim Becker]

Is this solid phenolic sheet or phenolic covered plywood? That can make a difference here relative to the best way forward.

[Robert Engel]

I've tapped into holes filled with epoxy and didn't have an issue. It has to be well-cured.

[Tom Bain]

Is this solid phenolic sheet or phenolic covered plywood? That can make a difference here relative to the best way forward.

Jim — It’s solid phenolic … also, I don’t have spare phenolic or the right sized plug cutter … which is why I was leaning toward epoxy or some other type of fill.

[Mark Bolton]

I'd make a plug of phenolic and epoxy that in the hole instead of just filling it with epoxy.

This is the most rock solid solution without a doubt even if the holes are on the small side. At least your repair will only have an epoxy glue line as opposed to solid epoxy that could just fracture out of the hole.

[Jim Becker]

Jim — It’s solid phenolic … also, I don’t have spare phenolic or the right sized plug cutter … which is why I was leaning toward epoxy or some other type of fill.

Sounds like a resin fill is your best, most immediately available, bet then. Let it cure fully with a generous amount of time and make sure things are well supported when you do the redrill so there's no wandering.

[Tom Bain]

This is the most rock solid solution without a doubt even if the holes are on the small side. At least your repair will only have an epoxy glue line as opposed to solid epoxy that could just fracture out of the hole.

Understood … I’m thinking I could order some phenolic dowels/rod material to use as a plug … any thoughts on where I might find that?