Dial-Set Compur shutter: adjusting fast speeds?

[evgenys]

Hello,

I recently made a simple shutter speed tester and checked the speeds of my old dial-set Compur shutter No.87654, which was lying unusable for a long time. As everybody can guess, the results I got are much different than the factory set speeds. That difference is quite big, but for my surprise the repeatability of the speeds are quite good (see the picture below).

The main thing I noticed is that there is no significant difference between 1/5 and 1/10 speeds (I think that because the fastest of the slow speeds is 1/5 sec and the slowest of the fast speeds is 1/10 sec, am I right?).

I know that there is the possibility to adjust the slow speeds, but what about fast speeds? Are they adjustable or I have to live with the results I’ve got? I’d like to adjust them, because 1/200 is usable sometimes.

I’ll be glad to receive the good advices and at the best the instructions how to adjust speeds, but not those which just advise to send the shutter to somebody else to CLA it for couple hundred of dollars.

Thank you,

Evgeny

[Bob Salomon]

A properly operating shutter is ±30% of the marked speeds. How close is yours to these tolerances?

[Nathan Smith]

The first step is a good cleaning. There was a web site that gave very good step-by-step instructions for a complete tear-down and rebuild of the dial-set, but I'm not finding it at the moment. If I locate it I will post the URL, in the meantime hopefully someone else has that link.

Cleaning and lubrication often helps the slow & mid speeds, but many (maybe even most) shutters will never regain their top speeds again without a new spring. Fortunately, that's not such a bad thing - I can live without the 1/400 if I have 1/100 and below.

[evgenys]

A properly operating shutter is ±30% of the marked speeds. How close is yours to these tolerances?

See the attached table. The top row is the marked speeds. The bottom row (red) is the real speeds. I suppose they are differs slightly above 30%.

[domaz]

Slow speeds in a dial-set Compur are determined by the timing gears. I would open it up and clean the timing gears (to the left of the dial when you open it up) with lighter fluid. Then put a little bit of thin oil around the gears, these shutters seem to like oil. I have brought a couple of these shutters back to life by oiling the gears. Here's a web page with pics and instructions.

[evgenys]

Slow speeds in a dial-set Compur are determined by the timing gears. I would open it up and clean the timing gears (to the left of the dial when you open it up) with lighter fluid. Then put a little bit of thin oil around the gears, these shutters seem to like oil. I have brought a couple of these shutters back to life by oiling the gears. Here's a web page with pics and instructions.

Thank you, but I made the cleaning by lighter fluid (but not oiling the gears) before I checked the speeds.

[John Koehrer]

On a rim set the change between high & low is 1/30 when a lever strikes a drive component of the slow speed gear train.
The high speeds were adjusted(?) by
1)replacing the drive spring and
2)swaging or filing the speed cam. It's just as much fun as it sounds.
If the high speeds are slow, it's possible that the blade housing or blade operating ring is dusty or dirty.

[E. von Hoegh]

Don't forget to degauss the shutter blades. Could get you as much as a stop.

[evgenys]

Don't forget to degauss the shutter blades. Could get you as much as a stop.

Do you know how to degauss them? I never heard of such procedure.

[E. von Hoegh]

Do you know how to degauss them? I never heard of such procedure.

Degauss = demagnetise. The shutter blades if of steel can become magnetised and cling to each other.
You need an open coil of copper wire, carrying alternating current. A watch degausser will do nicely. Hold the shutter or blades in the energised coil, and slowly move them out and as far away as possible before shutting off the power.
A friend pointed this out to me, it was a real "why the hell didn't I think of that" moment.