Grytpype
Well-known
I'm dismantling a 1937 Sonnar 13.5cm for a de-fungus and lube. I had hoped this would be a similar disassembly to the Jupiter-11 described on the Kiev Survival Site, but the construction of the lenses turns out to be substantially different, at least as far as the focus-mount is concerned.
I need to remove the outer helical from the barrel in order to detach the helical guides (see picture). It is screwed into the barrel (with several shims between) and locked with 3 screws, and it is screwed in TIGHT! I think that the factory probably tightened this utilising the step on the back of the outer helical that acts as a stop for the close-focus stop-screw on the inner helical, but there is no provision for unscrewing it. I drilled a couple of 1mm holes in the front face of the outer helical and I devised quite a sturdy tool which gave me a very good purchase on the parts, but could not shift them, even after soaking in WD-40 and heating the barrel with a blow-lamp. Finally, I managed to apply enough force to destroy the tool.
It looks as though the only solution that does not risk destroying the lens is to clean the helical by immersion as best I can, with it assembled, and then to work grease in from the outside. This will take some doing because there is a lot of brass swarf in the helical left from when I drilled my holes!
I can't see any rational reason why this assembly would have a left-hand thread, but does anyone know otherwise? This at least would explain the difficulty.
Steve.
I need to remove the outer helical from the barrel in order to detach the helical guides (see picture). It is screwed into the barrel (with several shims between) and locked with 3 screws, and it is screwed in TIGHT! I think that the factory probably tightened this utilising the step on the back of the outer helical that acts as a stop for the close-focus stop-screw on the inner helical, but there is no provision for unscrewing it. I drilled a couple of 1mm holes in the front face of the outer helical and I devised quite a sturdy tool which gave me a very good purchase on the parts, but could not shift them, even after soaking in WD-40 and heating the barrel with a blow-lamp. Finally, I managed to apply enough force to destroy the tool.
It looks as though the only solution that does not risk destroying the lens is to clean the helical by immersion as best I can, with it assembled, and then to work grease in from the outside. This will take some doing because there is a lot of brass swarf in the helical left from when I drilled my holes!
I can't see any rational reason why this assembly would have a left-hand thread, but does anyone know otherwise? This at least would explain the difficulty.
Steve.
Grytpype
Well-known
Well, it looks as though the answer to my original question is "No, nobody has"!
I soaked the assembly in 'brake and clutch cleaner' which is my solvent of choice for immersion cleaning. This cleared the brass swarf and the last traces of oil from the grease, but left a residue of the 'soap' base from the grease which is insoluble in any solvent I have ever found. A few months ago I bought one of those cheap little Chinese ultrasonic cleaners, but had written it off as useless. I tried it on this job and it certainly did seem to clear all the visible grease residue. I cannot be certain how effective it was in the invisible reaches of the helical grooves, but the helical feels quite smooth, even before greasing.
On the plus side, being unable to remove the inner helical means that I do not have to worry about whether I can re-assemble it tightened to exactly the same position - an error would affect the position of the focus markings and stops relative to the rangefinder.
Steve.
I soaked the assembly in 'brake and clutch cleaner' which is my solvent of choice for immersion cleaning. This cleared the brass swarf and the last traces of oil from the grease, but left a residue of the 'soap' base from the grease which is insoluble in any solvent I have ever found. A few months ago I bought one of those cheap little Chinese ultrasonic cleaners, but had written it off as useless. I tried it on this job and it certainly did seem to clear all the visible grease residue. I cannot be certain how effective it was in the invisible reaches of the helical grooves, but the helical feels quite smooth, even before greasing.
On the plus side, being unable to remove the inner helical means that I do not have to worry about whether I can re-assemble it tightened to exactly the same position - an error would affect the position of the focus markings and stops relative to the rangefinder.
Steve.