What size machine screw is Sink Waste

[Diyisfun]

Need to replace sink drain plug (due to leak), bought new kit, but screw is to short. As you see in this image previous person has used a bolt.
I need to buy new screw what diameter is it? it measures at 4/5 mm not easy to measure, also what head is it, although that's not that important.

 

[Madrab]

May be an M4 or M5 countersunk ...

Or stop being cheap and just buy a new waste for £3 with everything in it .....

 

[oldbuffer]

You'll need to measure the diameter of the screw properly. Put it on a ledge with a block of wood (or similar) either side, close the wood to the threaded part of the screw, make sure the two blocks are parallel and measure the gap.

Alternatively, wrap a piece of paper round the screwed part, pinch it tight, mark the points either side, flatten out, measure between the lines, multiply by 7 and divide by 22 to give (approximate) diameter.

The diameter is likely to be a little smaller than the nominal size of the screw, say 3.9mm for M4, 4.9mm for M5, 5,9mm for M6.

Try and get a stainless steel screw.

 

[Diyisfun]

Need to replace sink drain plug (due to leak), bought new kit, but screw is to short. As you see in this image previous person has used a bolt.
I need to buy new screw what diameter is it? it measures at 4/5 mm not easy to measure, also what head is it, although that's not that important.

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I bought a new waste. The screw wasn't long enough. It would have been OK for a stainless steel sink, why don't they just supply a long screw that will work on all sinks.
I ordered 4 & 5 mm screws it was a 5mm x 50mm that did the trick

 

[Nige F]

I got a waste kit from PTS and the flippin screw is about 15 mm too long for s/steel - lucky I've got a power screwdriver

 

[ReganAndCarter]

Can you take the screw down to your local iron mongers to match it up with something longer?

 

[Diyisfun]

HeHe ironmongers, I live in the sticks.
Guess the size, order on Ebay & wait.

 

[Diyisfun]

I got a waste kit from PTS and the flippin screw is about 15 mm too long for s/steel - lucky I've got a power screwdriver

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Looks like you had my 15mm, now behave.