On 22/05/2021 20:42, newshound wrote:
On 22/05/2021 19:25, Joey wrote:


"Harry Bloomfield"; "Esq." wrote in message
...
Last time I used the car, as I parked up in my garage back home, one
of the lenses of my driving glasses fell out, just as I removed them.
The clamp screw had udone itself, releasing the lens. In a bit of a
rush, I just tapped myself down, hoping the screw would land on my
seat, so I could find it later.

Getting the car out yesterday, I realised I forgotten to deal with
the problem, so I searched the seat, the car floor and the garage
floor without finding the missing screw. I grabbed the glasses and
lens, to take indoors to see if I could find another to fit, only to
find the missing screw still caught in the frame. All it needed was
the lens put in place and the screw tightened into place.

All of those screws have been captive screws with all of my frames
and I have had lots over the 65+ years I have been wearing glasses.

Often not sufficiently captive though. They seem to be centre punched to
secure them; presumably glasses shops have a neat jig for holding them
securely, with either a press or a guided punch. I have often thought
about asking them how they do it.
None of my glasses have ever had captive screws. Fortunately I have a
decent stock of obsolete glasses for spares



--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal