How to mend a broken key for peanuts (well, almost)

[MistralS60]

This note will probably apply to any 5-button key, not just P2 ones.

One of my P2 S60 5-button keys having been broken in mysterious circumstances, no-one knows how, I set out to avoid paying north of £150 for a replacement. The blade was broken at its base end where it is weakened, presumably by design to avoid it damaging the driver in a shunt.

First I bought a blank, complete with plastic mount, springs, etc, here for under £6 including 1st class postage, then set out to find someone to cut it. Apparently these keys have to be cut by laser, so a few enquiries were needed, but I was told of a master locksmith not too far away who charged me £20 to cut it. I've since been told he's expensive, so you might get it done for less.

This gentleman said that as the unbranded blanks vary somewhat in size he couldn't guarantee the key would be any good, but having miked up my blank he said it should be OK, and so it has proved. I don't know if the blanks from any one supplier vary in size.

Now for the sticky bit. The transponder - the bit that has to be coded so that the car will accept it and start - is a sealed glass tube about 11 x 2mm and lives in the slot arrowed in this pic, borrowed from the seller's listing, which I assume is in the public domain. At least the transponder isn't moulded into the plastic !

IME, if the two halves of this part of the key aren't stuck together in the factory as would make sense from Volvo's POV, they need to be stuck by the user to stop them falling apart in use, which makes it difficult to extract the transponder without breaking it.

Not knowing what I was looking for I used a razor saw, screwdrivers and BF&BI, but if I do it again I'll try cellulose thinners, acetone, and dilute nitric acid in that order to dissolve the plastic. (But HNO3 will dissolve the metal part as well.) Actually, now we know where the fragile bit is, a carefully placed saw cut, followed by some levering, would probably do the trick.

Having thankfully found the transponder intact I put it in the new shell (it needs a gentle push), fiddled the spring etc into place, and superglued the lot together for the reason hereinbefore stated.

HTH !

[MistralS60]

Cellulose thinners won't dissolve the plastic. Does anyone know of something that will, short of nitric acid ? I think I'll try caustic soda next. At least that won't go for the glass or metal.

[hillmangt]

Carr's Butanone solvent melts some plastics. It is highly volatile and extremely inflammable.
Used by modellers to fuse plastic kits together.

[MistralS60]

Thanks, GT, sounds just the stuff !

A quick look on The Bay reveals that 2-Butanone is also known as Methyl Ethyl Ketone or MEK, which I've met. Is that the same stuff ?

I hardly need a litre so I'll try its relative acetone (nail-varnish remover, which I can pinch from She ).

[hillmangt]

Yes I believe MEK is the same stuff.
It should be available from modelshops in small bottles.
Not sure if acetone will work.