Back box screw holes threaded.

tom1ie · 31-08-2024 9:08pm #1

hi all,

I’ve an issue in the bathroom with the light switch. The plate is lose and one of the screw holes has no thread to take the screw, the other screw hole allows the screw to tighten only so much and then it pops loose over time.
I can’t replace the back box as the edge of a large tile is overhanging the back box on all four sides of the box.
Is it possible to retap the screw holes or has anyone got any alternatives for this?
thanks for any help and guidance.

drury.. · 31-08-2024 9:15pm

https://www.boards.ie/discussion/2058367139/back-box-screw-holes-threaded

3.5 pozis is the usual solution I used , they usually grip when the standard screw doesn't

Watch u don't nick a wire

Probably other ways too

tom1ie · 31-08-2024 9:46pm

https://www.boards.ie/discussion/comment/122568901#Comment_122568901

yeah get ya, the only thing is it’s a chrome switch plate so a pozi head might look shite against the chrome if ya get me.

drury.. · 31-08-2024 9:52pm

Pozis may not fit the chrome type anyhow

Hole can be smaller on them

con747 · 31-08-2024 9:56pm

https://www.boards.ie/discussion/comment/122568984#Comment_122568984

Maybe some threadlocker with a bit of plumbers tape pushed in to the threads first?

https://www.woodies.ie/loctite-threadlocker-1186235

drury.. · 31-08-2024 11:19pm

The ptfe on the screw might be a solution, haven't tried it .Don't think i'd bother with thread locker as it won't be a reusable solution

Another method might be to drill and tap the back of the box . Extension stud or long screw into back box

Occasionally I think i've compressed the screw lug and re-threaded it .That would be a bodge if even successful

The 3.5 mm pozi is the go-to method for white accessories .

Theres probably other ways as it's a common problem

10-10-20 · 01-09-2024 11:26am

I did this once on a solid wall (not going to work on stud. Drill it with a 6mm bit and fit a rawl tightly, then screw in a screw-extension (or two) to provide threads. Only thing is that you have to get the alignment right when you drill, otherwise it's a mess.

https://www.toolstation.com/extension-studs/p79641

tom1ie · 01-09-2024 12:02pm

https://www.boards.ie/discussion/comment/122570043#Comment_122570043

oh now I like that.
I didn’t know you could get them at all.
I would indeed be drilling into a solid wall so i take it I have to:

Turn off power (of course!!)
drill out the old threads (what’s left of them anyway) with a metal bit to allow 6mm masonry bit to be used.
drill 6mm holes with masonry bit
Insert red rawl plugs
Screw in extension studs (actually how do you do this? Is there a slot to allow a flat head to screw the extension into the real plug?)
Refit switch plate and screw original screws into the extension studs.

One other question- how long is the threaded extension? The back box I have is a shallow one 25mm or something so the threaded extension would have to be less than that

Great idea

10-10-20 · 01-09-2024 1:48pm

A 6mm nut driver is what I used to screw them in.

They are this depth…

tom1ie · 01-09-2024 1:55pm

https://www.boards.ie/discussion/comment/122570456#Comment_122570456

Thanks very much, that’s great info.

smuggler.ie · 01-09-2024 3:23pm

https://www.boards.ie/discussion/comment/122570043#Comment_122570043

Great idea, will keep it for future.
I'd say it would work on timber background too (smaller hole to drill)
Also, once happy with alignment, i would put dab of PVA(other) glue on the extension threads - prevent screwing out if ever would need to remove/replace wall plate and/or grease on final plate screw to prevent seizing.

other potential solutions could be:
1.providing it wont stick out, get matching thread nut(drywall/plastic boxes have threaded inserts that could be used ) and tighten extension from behind the "damaged" ear. Defo want to seize the nut to prevent turning after