[EE] Obscure screw size
I have a Hammond 1551R box into which fits a small PCB.
The recommended shape of the PCB is given in the datasheet:
I have received the PCB and it fits perfectly, but the Hammond box only
came with the 2 screw for the lid and none for the PCB mount holes. The
sizes specified are 2.5mm for the PCB hole diameter, but the screws are
given as 32 x 3/16" self tapping.
So the question is - what does this translate to in metric sizes? I get
the 3/16" is probably the length, but what does 32 stand for? Is it for
a 1/32" thread?
I have trawled through pages and pages of all the many different
"standards" - Whitworth, BAS, UTS, etc but I can't fit 32 into anything
that seems to fit properly.
The UTS (Hammond are US so I assumed this would be the most likely) is
specified as X-Y where X is the diameter and Y is the thread turns per
inch. 1/32 would give a diameter of 0.8mm and 3/16 means nothing in
terms of turns per inch. Even if you swap them round it doesn't make sense.
Whilst linking to the above datasheet I noticed it's actually different
from the one I have, and gives #2 x 3/16" instead of the aforementioned
32 x 3/16". This makes more sense as #2 equates to 2.18mm diameter
shank, but I'm still unsure as to the thread (not that it matters too
much as it's self tapping, but I'd like to know anyway)
I'm going to order some number 2 screws, but can anyone help me to
confirm exactly what the numbers mean for future reference?
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