Tight backnut

[lipidicman]

My baths plastic backnut is tight all the way down, like it is crossthreaded. I have a plastic bath and I have managed to move it about 1mm down. Should I try to cut it off?

Alternatively I have been trying to use a 'claw' tap wrench (dont know the correct term). My cast iron 'basin wrench' doesnt fit, this type of tool might help me budge it - the claw is just shredding the hexagon shape away. I cant find a 'bath wrench' - are back nuts a standard size and what size are they?

 

[Bahco]

Should be 3/4 bsp. Use a heated screwdriver to melt the nut off or a blow torch. Safety first when doing this i.e goggles and gloves etc.

 

[lipidicman]

Scared of melting it off as the bath is plastic/fibreglass

 

[Bahco]

Try the hot screwdriver carefully.

 

[lipidicman]

OK, success. The cheapy steel template tool from Wickes did a nice job. It took about half an hour as the nut really was tight all the way down.

I now have another problem. The backnut is only just bigger than the hole in the bath - I mean 1/2mm on each side. I was hoping to get a washer that would snugly fit the tap thread, but have a larger outer diameter than the backnut. My plan was to silicone this in place and then apply silicone to the underside of the mixer and sandwich this down for a nice seal. However I cant find a washer to do this. The square based top hats are only a little bigger and the standard 3/4" washers are the same size as the backnut. My father suggested a piece of marine ply with holes drilled to match the taps and to silicone the whole thing underneath. He also said people used to use lead. Any ideas?

 

[Tinitus]

hi there is a new type of washer just for taps called split click , plumb centres and some plumbers merchants sell them, they centralise the tap and also stop the tap from coming loose would also advise buy brass backnuts far better and slightly bigger good luck.

 

[ChrisR]

yes they are quite good but again probably not big enough. I've always got away with a top-hat washer all filled with silicone, when I haven't had a bit of lead available. Oh yes, marine ply isn't too bad..

 

[brumylad]

could try an off the shelf solution

ESSEX FIXATAP for acrylic baths

http://www.andyplumb.co.uk/asp/catalogue/catsearch.asp?catval=101

 

[lipidicman]

yes they are quite good but again probably not big enough. I've always got away with a top-hat washer all filled with silicone, when I haven't had a bit of lead available. Oh yes, marine ply isn't too bad..

Got some top hats, just concerned that if I fill it will silicone this will jam the thread up and make a real mess. Will the tap be removable if the thread has silicone in it?

I am probably going to go with the larger polythene washer and the use of silicone to set the tap and fill the hole between the tap and the washer underneath. If not this will fill with nasty stagnant smelly water.

 

[ChrisR]

With the proper spanners you'd get it off even if it were stuck with silicone. You don't want water running through there, or sitting. as you say.
On old baths the holes were square and the corners aren't covered by modern taps so you have to fill with silicone.