Natural Science Forum / Physics / Optics / January 2006

Hi,
I can only tell you that for metric screws, there are screws which have a
pitch of 0.5mm, 0.75mm and 1mm. And for a 3mm screws I guess, the correct
pitch could be either 0.5 or 0.75mm which you need.
If you need, I could get 3mm screws for you from a local hardware store here
in Austria or Switzerland and mail them to you - but you might need to wait
a week or so to get them.
Cheers George Nyman

First go to another store.  You need one with a huge assortment of screws.
Here in Atlanta there are two stores out of , gosh, how many hardware stores
that have large assortments of metric screws or use the internet.

When your buying a screw you need to know the head type (pan, cheese, etc.),
the size (diameter in mm.), the length and the screw type (see George's
post).  It also helps to know the metal type you can use or the minimum you
will accept.  Last but not least if the don't have, say,  the head type then
what will you accept.  It really help to know how to cut a screw, sometimes
you can get a perfect screw but its to long.  Get familiar with cutting
screws.  The key is to put a sized nut on the screw just below the cut line,
this keeps the threads in good shape and use a good, sharp cutter.

All ways buy more than you need, you never know were the second screw will
run of to.

Some screw, Zeiss is famous for this, are custom.  Good luck replacing
these.  Sometimes you can make a replacement for one screw our of several
easily made parts, sometimes your just screwed.

Good luck!

Kevin Cunningham
SMS

The metric screws are fully designed by their diameter and pitch. If
you ask a metric screw giving its diameter only, you will obtain the
'normal' pitch. For a metric screw of 3 mm of diameter, the normal
pitch is 0.5, but there are other pitches. With a microscope, it
should be easy to determine the pitch of that screw. (Check also that
the hole is free).

Logos
giocar44ABC@alice.it
Remove A B C

Been there, done that!!
I'm just a hobbiest, but if you have any on-going needs for "J. C.!!!"
screws of odd sizes, here's two suggestions:  old cameras and camera
lenses can be a good source--some camera shops and camera shows have
boxes of "dead" lenses and cameras, for a buck or less, which can be
disassenbled and their tiny treasures salvaged.  Also, and some purists
on this site may blast me to Pluto for this---if the scope is to be
fixed for real-world use, not as a collectable piece, re-tapping the
hole with a slightly larger, more common screw size might be the most
reasonable solution----ouch!!!!!!!
Bob Marable

I thought Nikon was using JIS. BTW, did you "Google" for metric screws (e.g.
http://www.microfasteners.com/catalog/products/MET.cfm)?

You can get a program that helps you convert from any standard system to any
other one (e.g. http://www.kisssoft.ch/english/manual/chap7.html)

Standards exist to screw anyone without access to a huge repository of
parts.

Gregor