I've lost a nut off my glasses and as a nut is likely to be cheaper than a new pair, I'll fix them. The trouble is, I'm not that familiar with tiny thread sizes. The bold is 1.31mm measured across the thread. What size is it? M1.6 or could it be an imperial size?
Take them to your opticians, they replaced a screw on mine for free
They are off the shelf reading glasses, not prescription lenses. I doubt they'd have spares. Nice idea though.
Can you improvise? I lost one of the screws out of mine and now both sides are held in with mig wire bent over top and bottom! They’ve been like that for about 2 years no problem.
Wild guess, 12BA has an od of 1.29mm so pretty close.
I'd still try an optician - they usually stock a variety of bits to try and repair many different types of glasses. I've never been charged for such a repair either.
quote:
Originally posted by BigFaceDave
Can you improvise? I lost one of the screws out of mine and now both sides are held in with mig wire bent over top and bottom! They’ve been like that for about 2 years no problem.
Like others vote optician as well, unless they are from the pound shop in which case I would buy another pair and rob the screws
from them and throw the rest away.
My mate buys his glasses from the pound shop. His eyes are such that he cannot read the figures on his car speedo 
,
yet can afford to go on 3 or 4 cruises a year. At this moment he's in the Norwegian Fiords, not that he can see them. 
Paul G
One of my local poundshops had a glass's kit, screwdriver and screws kit for a quid,
but my eyesight wouldn't be up to fiddling with those tiny screws!
Now at my age even 5mm bolts are tricky
steve
[Edited on 30/4/18 by steve m]
I'd start with an optician as well even if they didn't supply the glasses.
SWMBO wears glasses and has had the same problem. Our local Specsavers have helped more than once for free.
We work with M1, M1.6 and M1.7s fairly regularly, could be any of those.
There's also the japanese screw standards for watches/glasses/optics. (JCIS)
http://www.japanesescrews.com/sections/screw-threads.html
Looks like it might be a 1.4?
[Edited on 30/4/18 by coyoteboy]
yes i was surprised as even a high st optician, just fixed mine for free and I was happy to pay
Whats wrong with a plaster like jack of you know what show
I bought a repair kit off ebay for a couple of quid. Nut spinner, pair of screwdrivers and a whole set of nuts, bolts and rubbery nose pads. So I went to the garage where I'd left the glasses after threadlocking 3 of the 4 nuts, only to find the lenses smashed. One had a big chunk missing and the other was cracked. Are plastic lenses attacked by threadlock? Could I have overtightened such a small screw enough to crack several mm thick plastic?
Polycarbonate is affected by direct contact and the vapours from uncured threadlock, causing cracking and embrittlement.
Other plastics and resins are also affected, there are special threadlocks for plastics.
Dave
a lot of the very tiny screws in spectacles are locked by 'deforming' the ends on the thread, and often have a central hole that a punch may be used