[rollei_list] Re: Checking shutter speeds...Compur shutters reliability
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 15 Feb 2007 11:49:11 -0800
----- Original Message -----
From: "FG" <fuktighet@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, February 15, 2007 10:55 AM
Subject: [rollei_list] Re: Checking shutter speeds...Compur
shutters reliability
Thanks for the figures, It is good to have an idea
(dimension) of what we
are talking about.
I have decided not to lube the shutter i've just fixed on my
rolleicord Vb
having in mind the dust that usually gathers around those
substances. At
least not extensively. Only a couple of drops spread around
with the help of
a q-tip on the parts that seemed to lead the movements.
(sounds imprecise,
but its actually better than it sounds).
Does anyone recommend a special lubricant?
thanks to all for the input.
regards,
juan
Most shutters will run dry if they are really clean. I
disagree with the idea that the main problem is dust
collected by the oil. In a properly serviced shutter there
is very little oil, my observation is that the oil oxidizes
or that something evaporates from it with time so it becomes
thick and hardens. The oil traditionally used on shutters is
similar to the oil used on watches and clocks. The modern
version of this oil is made of silicon and does not age.
Oil can be applied with a watchmakers oiler,
essentially a wire with a thickened end but those are
expensive and occasional work can be done with plain wire or
with the tip of a very fine brush, like the kind used for
spotting prints. Where a brush is used the oil is first
placed on a clean surface like a small saucer and brushed
out thin. Then a very small amount is picked up on the end
of the brush and applied where needed. Mainly the points to
be oiled are the trunions or bearings of the gears in the
speed regulator. A small amount can also be applied to the
surface of the pallet. The gears in other regulators in the
shutter like the flash synchronizer or self-timer should be
treated the same way. This is a tiny amount of oil. Good oil
is available from Nye and called Nyeoil. Watch oil does not
creep and does not harden up with age.
Compur also recommends lubricating some surfaces with a
light grease. These are sliding surfaces such as the edge of
the speed ring where it contacts the body of the shutter.
The grease can also be applied with a brush and brushed out.
The right grease is also a silicon based synthetic.
The instructions for the late Compur shutters, which
use spiral springs similar to those in a clock motor, is to
grease them lightly with a Molykote type grease. This is
also OK for the other grease points.
Compur specifies half a dozen different lubricants in
the instructions for various shutters. Unfortunately, they
are listed by brand names or by Compur stock numbers rather
than description. The brands are, of course, German, so it
may be difficult to identify the particular product referred
to.
Light silicon oil is also sold in hobby shops that
specialize in model trains under the Le Bel name but I have
found it less effective than the Nye oil Nye lubricants can
be bought over the web.
Probably the best solvent for shutter cleaning is
Naptha. Its available in most hardware or paint stores. A
quite pure Naptha is available as lighter fluid under the
Ronsonol brand. Other good solvents are pure (99%) Isopropyl
alcohol, which is available from many drug stores and is
also sold by Fry's and other computer stores for cleaning
electronic components. Its important to use _dry_ alcohol
and not rubbing alcohol which has a substantial amout of
water in it.
The best solvent of all is 1,1,1,Trichloroethane. This
was once widely available but is now considered a serious
environmental hazard so it has become hard to find and
expensive.
Do NOT use Acetone on any part of a shutter, it is not
selective enough and will remove many kinds of paint and
dissolve some plastics.
Do NOT ever use powdered graphite on a shutter. Somehow
this is often recommended but NO shutter manufacturer has
ever used it or recommended it.
Have a care about using cotton swabs, they shed and the
fine cotton fibers may be difficult to spot and to remove.
They can jam up an otherwise good shutter.
I strongly recommend obtaining whatever factory
information is available on the shutter you intend to work
on. It is very easy to get a shutter completely jammed by
popping a lever out of place. The drawings will help in
figuring out what has happened and getting it back
correctly.
A properly cleaned shutter should work for many years
without further attention. Compur shutters, in particular,
are pretty well sealed, the main openings being the slots
for the cocking and tripping levers and the iris control
lever. In a Rollei camera these are further protected by the
shroud over the front of the camera.
It is vital that the shutter blades be scrupulously
clean and free of any oil or other residue.
Another note: There are really no speed adjustments on
most shutters. The Compur shutter has an adjustment for the
speed regulator, which is removable. One end can be slide a
little. The correct adjustment will get the slow speeds
right. On some shutters the position is adjusted for 1/10th
second, on others for 1 second. High speeds are mostly a
matter of the frictional forces and inertia of the moving
parts. The speed ring is adjusted at the factory by grinding
the surfaces that contact the levers on the speed regulator.
If they are ground down too far they are swaged back with a
small chisel. Once they are set they should not ever need
attention.
Springs do not weaken from being under tension or
compression unless the elastic limit of the material is
exceeded. They are weakened by work hardening from use.
Probably most shutter springs thought to be weak are not so,
the speed reduction being caused by friction, or they have
been damaged (stretched for instance) by careless handling.
The spiral springs used in dial set Compur and in Compound
shutters, and in the latest Compur shutters, which use clock
motor type springs, are under considerable tension all the
time. When the shutter is cocked they are wound just a
little more. This motor was designed for the shutter in the
Hasselblad camera which is to be left cocked all the time.
Later Compur shutters use helical springs (like a
screen door spring). Many shutters, like Ilex, Wollensak,
and several Japanese shutters, use hair springs. These are
made of spring wire, like piano wire, and are reasonably
easy to make if they need replacement or or missing. Howver,
one must know how the original was shaped and what guage
wire it was made of.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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