Kim Coxon
Moderator
There have been several threads recently on "unsticking" "sticky" parts and the use of the lighter fuel "cure". There does there seems to be a little confusion of how this works and when it should be used. Hopefully, this will clarify things a little but please bear in mind, it is my own view and I am not a pro repairer!
Certain parts of a camera mech are designed to run "dry" with no lubrication. Typically, these include leaf shutters, the blades of diapraghms and slow speed mechs. There is a very good reason why they run dry. Any lubricant will affect the speed they operate because of surface tension and this will depend on the amount of lubricant. By running them dry the speed is predictable. There are normally quite close tolerances and any oil or grease contamination will slow them down and enough will cause them to jam. A good example of this is the stuck shutters in Canonets and reluctantance of the slow speeds in this type of camera. The solution to this is to clean all the muck away. With Canonets and others, you can normally achieve this by "flushing" the muck away with Ronsonol or similiar. The best cure for slow speed mechs is to take the mech out and thoroughly rinse it out in solvent. The only lubricant such mechs will ever require is a very, very small amount of dry graphite and this is rare.
Certain parts of focal plane shutters do need a very small quantity of lubricant such as very fine watch oil. Over a period of time, this can dry out and result in lazy shuuters and capping where one blind runs faster than the other. The cure for this is generally a professional CLA. It needs specialist tools such as shutter timers to set up correctly. Unfortunately, the problem can be masked by increasing the tension on the blinds thus overcoming the extra friction. This appears to be a quick, cheap fix and you will see people offering this as a "cure". However, it is not a cure. It hides rather than cures the problem and over a period of time can cause long term damage.
The third category of lubrication is grease. This is normally used in the focus helix of the lens and serves 2 purposes. It not only makes the focus mech smooth to turn but it also "damps" it and can take out any excess "play". This is particularly true of the FSU lenses! Any natural oil based grease will decompose over a period of time. The original grease used by most of the FSU makers in particular was almost like a wax to make up for poor manufacturing tolerances. This wax gets very sticky when it breaks down and this shows as a very stiff and "jerky" focus. As the grease breaks down, it tends to release some of it's oil and gets thick. Such a grease cannot be reconstituted. If you apply a little solvent such as lighter fuel, it may make it seem better but in reality you have hidden rather than cured the problem. As soon as the solvent fully evaporates, you are back where you started. The only long term solution is to clean all the old grease away before applying new stuff. If you don't clean the old grease away, you are again hiding the problem. If you use a fully synthetic high grade grease, the solution will last much longer. Automobile wheel grease is no good for this. The oil comes out far too easily and it breaks down relatively quickly. The oil, when it comes out, migrates around the camera and you end up with the problems outlined in the first paragraph! This will be greatly accelerated by heat so don't leave your camera in the car on a warm summer's day!
In summary then, the lighter fuel cure works well for things such as stuck leaf shutters and auto diapraghms such as on Canonets. For focus mechanisms, it is next to useless and the only long term solution is to give them a full clean and relube with high quality grease.
Regards
Kim
Certain parts of a camera mech are designed to run "dry" with no lubrication. Typically, these include leaf shutters, the blades of diapraghms and slow speed mechs. There is a very good reason why they run dry. Any lubricant will affect the speed they operate because of surface tension and this will depend on the amount of lubricant. By running them dry the speed is predictable. There are normally quite close tolerances and any oil or grease contamination will slow them down and enough will cause them to jam. A good example of this is the stuck shutters in Canonets and reluctantance of the slow speeds in this type of camera. The solution to this is to clean all the muck away. With Canonets and others, you can normally achieve this by "flushing" the muck away with Ronsonol or similiar. The best cure for slow speed mechs is to take the mech out and thoroughly rinse it out in solvent. The only lubricant such mechs will ever require is a very, very small amount of dry graphite and this is rare.
Certain parts of focal plane shutters do need a very small quantity of lubricant such as very fine watch oil. Over a period of time, this can dry out and result in lazy shuuters and capping where one blind runs faster than the other. The cure for this is generally a professional CLA. It needs specialist tools such as shutter timers to set up correctly. Unfortunately, the problem can be masked by increasing the tension on the blinds thus overcoming the extra friction. This appears to be a quick, cheap fix and you will see people offering this as a "cure". However, it is not a cure. It hides rather than cures the problem and over a period of time can cause long term damage.
The third category of lubrication is grease. This is normally used in the focus helix of the lens and serves 2 purposes. It not only makes the focus mech smooth to turn but it also "damps" it and can take out any excess "play". This is particularly true of the FSU lenses! Any natural oil based grease will decompose over a period of time. The original grease used by most of the FSU makers in particular was almost like a wax to make up for poor manufacturing tolerances. This wax gets very sticky when it breaks down and this shows as a very stiff and "jerky" focus. As the grease breaks down, it tends to release some of it's oil and gets thick. Such a grease cannot be reconstituted. If you apply a little solvent such as lighter fuel, it may make it seem better but in reality you have hidden rather than cured the problem. As soon as the solvent fully evaporates, you are back where you started. The only long term solution is to clean all the old grease away before applying new stuff. If you don't clean the old grease away, you are again hiding the problem. If you use a fully synthetic high grade grease, the solution will last much longer. Automobile wheel grease is no good for this. The oil comes out far too easily and it breaks down relatively quickly. The oil, when it comes out, migrates around the camera and you end up with the problems outlined in the first paragraph! This will be greatly accelerated by heat so don't leave your camera in the car on a warm summer's day!
In summary then, the lighter fuel cure works well for things such as stuck leaf shutters and auto diapraghms such as on Canonets. For focus mechanisms, it is next to useless and the only long term solution is to give them a full clean and relube with high quality grease.
Regards
Kim
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