Gauthier shutter speeds
I have tried to CLA some Gauthier shutters (Prontor *, Vario). The last one was a Vario on a Nettar and is typical for the ones I've tried to improve:
1/200 is 1/200+
1/75 is around 1/55
1/25 is more like 1/16
After cleaning with CRC (it didn't really look gummed or dirty) I ran it dry with no change in speeds. Then with tiny amount of oil on the shafts and teeth in the gear train. No change after that either.
Is the delay coming from somewhere else, like weakend spring or something? What's your experience with these shutters?
Expect manufacturing tolerances of around +/- 20% - add in some wear and yours seems about right and well within the exposure latitude of film. Gauthier shutters are designed to run dry, there is no need to put any oil anywhere.
Most of us would be very pleased with those results. You couldn't do any better, even if the shutter was brand new.
Just flushing with the components in the shutter will not get the gunk out. You have to remove every thing, flush, lube, reassemble.
A light sheen of oil is all that is needed, any more acts like glue.
Light weight grease is better on the gear teeth, again just a trace.
The main plate needs to be removed, the shutter blades and controller removed from the plate, cleaned, and lubed with an extra fine dry powder lubricant such as extra fine powdered graphite.
Adjust the 1 second or the lowest shutter speed for correct for the best chance of other speeds being correct. Older spring tension shutters can be improved by increasing the springs tension, if the spring arms are at 45° to each other uninstalled increase the angle to 50° to 55° without distorting the springs center. Extension springs can have 1 to 3 turns removed and the end reformed to the attach end shape.
Speeds above 1/100 - 1/125 use booster springs to achieve the speed, sounds like yours is good.
Speeds 1/100 and slower are 20% tolerance, Speeds 1/125 and faster are 30% tolerance or roughly 1/3 stop either side of the marked speed.
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