Cannot tighten 2 gang switch to wall

[b13kal]

There is another option , if the back box is available , the lungs can be changed ? Apple are easy to change ?

 

[333rocky333]

If there old boxes they may be imperial thread which is larger than 3.5mm,did you keep the existing old screws

if your using new 3.5mm screws its may be there wrong size for the holes and the reason there loose, therefore rethreading at 3.5 will be pointlesss

 

[EnfantTerrible]

If there old boxes they may be imperial thread which is larger than 3.5mm,did you keep the existing old screws

if your using new 3.5mm screws its may be there wrong size for the holes and the reason there loose, therefore rethreading at 3.5 will be pointlesss

Screws are the same as old ones (I kept them). I'll do the rethreading after work tomorrow and report back!

 

[333rocky333]

Visibly they look similar have you tried with the old screws or just the ones supplied with the new switch and the ones you brought.

If you say the screw pulls right out then the lug is sheared rather than the screw.

Personally I dont see how you can cut a new 3.5 thread into a sheared 3.5 lug.
That would only work if the screw thread was damaged and the lug ok, which if that was the case the screw would be unlikely to pull right out.

 

[EnfantTerrible]

I was going to try squeezing the lug slightly to make it oval so I can cut a thread into it but yeah, I thought the same time thing about cutting a 3.5 thread into a sheared 3.5 hole.

It's definitely the lug and yeah, I tried the old screws but same problem. Fine until it starts getting tight then it just loses bite and spins freely.

I liked the idea of glueing nuts to back of lugs so if rethreading fails, I'll try that.

 

[Scoby_Beasley]

You can also get a 4mm re-thread tool that's not really for the likes of back boxes but if you've stripped a 3.5mm thread you may find the 3.5mm re-thread tool will just fall through the holes, as do your screws.

You just need to get some 4mm threaded screws then. Oh, and be more gentle in future!!

 

[bernardgreen]

Spire clips might be the answer, I haven't tried them in back boxes so cannot say if they will fit on the lug.

http://www.wurth.co.uk/data/productdocuments/010096.pdf

 

[EnfantTerrible]

OK my shopping list for today is:

Rethreading tool m3.5
Rethreading tool m4
Pan Head Machine Screw BZP M4 x 20mm Pack of 25

First I'll try rethreading at m3.5 with the lugs slightly squeezed into an oval. If that fails I'll rethread at m4 and then use the m4 screws. I'm guessing I'll need to drill 4mm holes into the switch cover as well for the screws to fit which means the little white caps that cover up the screws won't fit anymore.

If all this fails I'll look into spire clips and/or gluing nuts to the lugs.

 

[Scoby_Beasley]

I'm guessing I'll need to drill 4mm holes into the switch cover as well for the screws to fit....

They'll usually drop in, plenty of clearance for the 3.5mm...

which means the little white caps that cover up the screws won't fit anymore.

Not seen those recently. But then I am blind!!

 

[EnfantTerrible]

I'm guessing I'll need to drill 4mm holes into the switch cover as well for the screws to fit....

They'll usually drop in, plenty of clearance for the 3.5mm...

which means the little white caps that cover up the screws won't fit anymore.

Not seen those recently. But then I am blind!!

Ah that's good then! I'll report back tonight

 

[EnfantTerrible]

Hi guys, just a quick update.

Squeezing the lugs with the grips and then rethreading them did the trick it would seem! I did test it with the 4mm screws and although they went through the holes in the swtich, the screw heads were too big and would stick out of the switch a little and look stupid.

Anyway, all done. Thanks for all your help!