[rollei_list] Re: rollei shutter sticking

My cord V did this -- but only in cold weather.  A cla every 4 or 5 years
kept the problem down.  First time was a bummer, though

Peter Nebergall

On Sun, 19 Feb 2006 14:52:07 -0800 "Richard Knoppow"
<dickburk@xxxxxxxxxxxxx> writes:
> 
> ----- Original Message ----- 
> From: <FSilberman@xxxxxxx>
> To: <rollei_list@xxxxxxxxxxxxx>
> Sent: Sunday, February 19, 2006 11:00 AM
> Subject: [rollei_list] rollei shutter sticking
> 
> 
> > Just wondering, but generally how long is the shutter stay 
> > timed before the
> > slow speeds start to lag or stick. I generally get a 2 to 
> > 3 of years & I
> > regularly use the camera & run lots of film through it. 
> > just wondering as I'm not
> > sure if the tech I use is doing as fair job or not?
> >
> > Best,
> >
> > Frederic
> 
>    There is no fixed time for this. It depends on the design 
> of the shutter, the kind (if any) of lubrication used, how 
> much the shutter is used, and the amount of dirt that gets 
> into it.
>    Nearly all high quality shutters made for the last ninety 
> years use a clock-work system to regulate the speeds. It is 
> usually the sludging of the lubricant in this mechanism that 
> results in the problem. Modern synthetic lubricants are less 
> likely to oxidize or to evaporate than those of the distant 
> past so the interval between needed servicing is much 
> longer. To some extent the sluggishness can also be caused 
> by absorption of fine dirt by the lubricant. The rate at 
> which this happens depends on the atmosphere and the design 
> of the shutter, i.e., some are more open to the air than 
> others. Reasonably frequent use of the shutter will tend to 
> keep it from getting sluggish.
>    Slow high speeds can also be due to weak drive springs 
> and to dirt on the shutter blades or in the blade driving 
> mechanism. Most shutters use a toggle arrangement to drive 
> the blades through a thin rotating ring to which one end of 
> each blade is connected. The blades slide against each other 
> and any residue at all will cause friction and slow down the 
> opening and closing of the blades. Normally, there is no 
> lubricant on the blades or the blade driving ring.
>    Springs are weakened by use. The repeated stretching or 
> compression of the spring can cause eventual metal fatigue. 
> The old warnings about leaving shutters tensioned are based 
> on a misunderstanding about springs. As long as the metal is 
> not stretched beyond its elastic limit constant tension or 
> compression will not weaken the spring. It is probably a 
> good idea not to leave some types of shutters tensioned 
> because there is force applied to various parts in the 
> shutter, but weakening the springs is not a problem.
>    So, as far as time interval, its not possible to come up 
> with an exact number because there are so many variables. My 
> Rolleiflex 2.8E was serviced by Harry Fleenor about ten 
> years ago and the shutter is still right on the nose. 
> Several shutters I've done myself also have not seemed to 
> vary over a very long time.
>    There is at least one reasonably priced shutter tester 
> available. The one I have came from Calumet, its nearly 
> doubled in price since I got mine but is still around $100 
> US. I have not checked to see if its still available, it may 
> be a victim of digital. Such a tool is very useful for 
> checking cameras for consistency and accuracy. If you are 
> doing commercial work I think one is nearly a necessity. It 
> will tell you immediately if there is a problem.
>    Keep in mind that the highest couple of speeds on most 
> shutters are marked for their _effective_ speed at full 
> clear aperture of the shutter. On Compur-Rapid and 
> Synchro-Compur shutters the top speed will read about 20% 
> low on a total open time tester such as the Calumet one. 
> This is normal but leads some people to think the shutters 
> are defective.
> 
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
> 
> 
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