Syncho-Compur DIY Shutter Repair Question

[jglavin]

Hi all, long time lurker first time poster.

Long story short, got a good deal on a 135 mm Symmar lens attached to a Synchro-Compur shutter (#051-24). Out of the box fast speeds all worked well, but at slow speeds the shutter would stick open and would require gentle to get it to close. I have repaired small things in the past so I decided to give it a go after scouring for repair guides and videos. I opened the shutter, removed the cam ring, cocking ring and got the escapement out, gave it a clean, lubed it up with watch oil and replaced all the parts. So far so good. Once reassembled fast speeds worked as usual, but now the slow speeds all seemed to fire fast too. Upon reinspection it seems like the pallet arm that controls the slower speeds doesn't want to follow the groves in its cam. It has no tension pushing it towards the inside of the shutter housing. When I cock it to a 1s position and place some gentle pressure on the pallet I can get the slow speed mechanism to work. I'm a bit stumped (having taken it apart and put it back together a half dozen times). I've read that some escapements need to have a spring set to a particular diameter to get the pallet to work, but that doesn't seem to be the case here. It also doesn't seem like the coverplate has any protrusions that interact with the pallet arm. I'm a bit at a loss but I feel like I'm so very close to getting the damned thing to work. Any advice would be amazingly appreciated. Some pictures for context:

[jglavin]

Update, it was a blasted little spring that wasn't seated. It must have gotten knocked off when I cleaned it. I hate springs. But now, onto the second step: getting accurate timing!

[Vaughan]

But now, onto the second step: getting accurate timing!

Ah. The timing of mechanical shutters... you'll need the manual for that.

My understanding is that for most shutter designs there is basically only one adjustment for all times, which is the position of the escarpment in relation to the shutter speed selector ring. The adjustment is limited because the shutter has been made so that it should be reasonably close just dropped in. Individual speeds are adjusted by filing away (to shorten time) or spreading out with a hammer and punch (to lengthen time) the individual flats on the speed selector ring. (This is why such shutters don't have intermediate speeds.)

Be very careful with lubrication. Generally they are dry because lubricants and grease are sticky which slows them down, and the stickiness changes with temperature which will affect the speeds. Often only points with high stress are lubricated like where the cocking lever touches the case. Again, follow the manual.

Many unreliable shutters can be fixed by cleaning out the oil that has been added by previous owners.

https://learncamerarepair.com might be a good place to find the information you need.

[paulbarden]

I can answer your questions if you still need assistance. I have serviced hundreds of Compur shutters of various designs.

[jglavin]

I can answer your questions if you still need assistance. I have serviced hundreds of Compur shutters of various designs.

Wow, thanks for the offer, Paul, it's very appreciated. At this point I'm trying to get the timing right (it seems a little long from an audio clip I recorded, with 1s = 1.2 or so and .5 = .6 etc.). Any pointers you could offer for that would be appreciated. Also, I managed to get a little finger smudge of oil on the shutter blades (I think you can see this in one of the pictures above) so any advice on how to clean that delicate part would be great too.

Thanks all!

[paulbarden]

Wow, thanks for the offer, Paul, it's very appreciated. At this point I'm trying to get the timing right (it seems a little long from an audio clip I recorded, with 1s = 1.2 or so and .5 = .6 etc.). Any pointers you could offer for that would be appreciated. Also, I managed to get a little finger smudge of oil on the shutter blades (I think you can see this in one of the pictures above) so any advice on how to clean that delicate part would be great too.

Thanks all!

The best thing I can do for you is point you to Chris Sherlock's Compur shutter service video, in which he demonstrates setting the speed train: https://www.youtube.com/watch?v=so0wjyq6y0g&t=14s

[kilimanjaro1996]

Your shutter is more accurate than 95% of the similar leaf shutter out there. Thus I won't fuss with the last 10-20%. It will be irrelevant for film photography, even for slides.

A tiny bit of oil can be wiped off by q-tip and lighter fluid.

[Vaughan]

1s = 1.2...

Firstly, audio clips are not reliable for measuring leaf shutters. Read up on "shutter efficiency" and think about whether you really want to embark on an adventure to calibrate your shutters at all.

Reliability and consistency are more important than accuracy.

For a 1 second exposure, a stop more is another 1 second, so 0.2 seconds is something like 1/5 of a stop, which as others have said is well within specifications. Something like 1/2 stop might be noticeable.

[paulbarden]

Acknowledging that what Vaughn says is very true, I would also say that the vast majority of Compur shutters (with a retard gear train of the type in the OPs shutter) can be calibrated such that all speeds between 1/15th and 1 second are very, very close to the speed intended. (The gear train governs only the speeds below 1/30th)
But for practical purposes, a shutter calibrated to deliver a 1.2 second exposure at tje 1 second setting is perfectly satisfactory.