Re: [Leica] BAD NEWS: magnetic screwdrivers

[John Collier <jbcollier@home.com>]

I may well be paranoid but here goes. Do not use a magnetic screwdriver in
small delicate workings. The screwdriver also magnetises the part you are
working on and this can cause problems down the road. Magnetic screwdrivers
are fine for screws because if fine metallic particles are attracted to the
screw, they will not cause any damage. Small parts or bearings that rub
against other parts can wear excessively or jam if metallic particles are
attracted to them. In my business we use magnetic screwdrivers on dash or
body screws but not on internal engine, transmission, etc parts. A small
warning from a slightly paranoid guy.

John "You talking to me?" Collier

> From: V8PWR@aol.com
> 
> I came back from my last mission in the UAE in a C130 hercules . A 4
> turboprop aircraft that has the particularity to send bad vibrations into the
> deepest part of your bones . ( some of you may know what I'm talking about )
> This fact is surely the cause of the front part of my 16 years old 35
> Summicron to slightly unscrew . This is no big problem if nothing goes
> further . But it was not the case .
> I carefully retightened the thing but , much to my surprise , the diaphragm
> wings where no longer closed into a round hole , but rather into an eggshaped
> hole : I mean they were loose in the lens , going where they wanted to .
> This is where I began to get chicken skin ! Really scared !
> Buy the way I tought It was no more damaging , at that point ,to remove the
> front element completly to see what was going on.
> After removing the front lens , there is another smaller one , that comes
> easily also . Then I found the internal diafragm ring , the one connected to
> the outer ring by a small screw . underneath all that you find the diafragm
> blades themselves .
> I can tell you that It took me 7 hours to put everything back in good order .
> The blades are only rotating around a very small axle ( smaller than 1/4 mm )
> and it is very hard to keep them where they are supposed to stay .
> I finally succeeded with a very small magnetised screwdriver and a plastic
> toothpic . 
> Now the 35 seems OK with no sign of damage but however it will go for a good
> CLA . 
> Still thrilling !
> Regards 
> Jo GOODTIMES