Compur sticking when fired

[johnnyrod]

More advice please! I am fixing up another Certo Sport Dolly for a friend of mine, it has a simple Compur shutter, 1-1/250, T, B, three shutter blades. The innards are very similar to my own with a Compur Rapid, at least above the blades.

B and T work fine, the escapement runs fine, I have cleaned the blades of (lots of) oil, and as far as I can tell, things look in the right place.
Main lever refitted by John Rodriguez, on Flickr
I haven't tried adjusting shutter speeds but they sound like they make sense (when it fires properly), and I have reset the hairspring tension. The problem is that when fired, sometimes the shutter jams before the escapement is started off. I can't figure out where this is happening. To release it I have to pull back the main lever a little and fiddle with the shutter release (though it might not be helping) and it releases in the end. This can happen on any speed including the top speed with the booster spring.

Also the self timer doesn't seem to work - press back the button to allow the main lever to move further when tensioning, but it fires instantly with the shutter release. Whether this has any bearing I have no idea.

I appreciate it's hard to work at a distance, but any thoughts would be greatly appreciated!
John

 

[Dan Daniel]

Have you cleaned the escapement? Taken it out, etc.? What other cleaning? Basically it sounds dirty. And maybe the escapement is not positioned properly.

 

[johnnyrod]

I don't like flushing so I've swabbed the shutter and aperture leaves, and everything I can get to. The escapement was soaked in hexane. When the shutter fires normally, it's fine, and runs down evenly, even at 1 second. When it jams, it's solid - I don't think it's the escapement sticking. More like something misaligned, but I'm not sure what. The shutter leaves stop half-way open when it sticks, so not yet open and the escapement hasn't yet started running down. Sometimes it fires just fine. I know what you mean about the position of the escapement from the last one of these, sometimes it can cause a jam. I have adjusted it back and forth a bit but it makes no difference.

 

[Dan Daniel]

Goo around the shutter blade ring, then, I bet. My limited experience with the older Compurs has always included the blade ring being dirty and needing to be stripped down and cleaned. When you say that the shutter blades had lots of oil on them, well.... I think you are in for a full strip down (don't open the aperture blade block, though, unless you are a very very patient and steady-handed person).

Also the escapement can be pivoted/adjusted on both ends in this shutter, I am pretty certain. There's a proper order for adjusting both ends. Someone posted a link to a Compur-Rapid repair manual recently that goes through this.

 

[citizen99]

With a shutter of that age, as well as cleaning the escapement, it helps to apply watch oil to the pivots. I use Moebius 8000, applied in *tiny* blobs on a watchmaker's fine wire applicator, looking through a watchmakers loupe. The tiny ampoules might seem expensive but one is likely to outlast more than the number of shutters that a private collector is likely to do in a lifetime 😉.

The escapement should be exercised to allow the oil to correctly distribute itself.

+1 what Dan said about the aperture blade block !

 

[johnnyrod]

Gents, I concur with you both - and I have the manual from my last advertures. Hopefully I've fixed it, though you'd have no chance without seeing it. It arrived in quite a few bits in the post, including the shutter plate already removed from the casing. Whether it was then or before then, the tip of one of the shutter blades (not the business end but the one that stays back in the outer part of the casing) has a slight bend. I think this is catching, maybe on another blade, maybe on part of the shutter casing/aperture plate. I did my best to uncrinkle it, and also rearranged the blades so it is pointing away from any of them. It has jammed twice, but not since. Hopefully it will be good enough, I need to set the shutter timings so will be firing it a fair few times yet. I still don't know why the self-timer isn't working, but this camera belongs to a friend and he never uses that anyway. It's missing the stops and datum mark for the focus ring, and generally looks like a bit of a Friday afternoon job on the inside. Still, progress of a sort! Many thanks for taking the time.