Stephen Prower
Well-known member
Lubricating focusser of old Japanese Porro with end cap of focusser shaft locked on solid
As I recall, a long time ago a poster on an old thread, possibly on BirdForum, said that it was his or her practice when relubricating the stiff focusser of an old Porro to add a little light oil to the original lubricant, but otherwise leave the original lubricant undisturbed.
I wouldn’t normally post, but I have never since reading that post read mention of the same practice again.
The spur is that yesterday I was grateful to the poster for describing his practice. I bought a battered old Japanese Porro that looked as though it might be capable of resuscitation. One job of work that was needed was to relubricate a stiff focusser. When disassembling the focusser of an old Japanese Porro, I usually remove an end cap to expose the end of the focusser shaft. I insert a screwdriver down the shaft, unscrew the focusser locknut, and proceed to complete disassembly.
But last night I couldn’t get the end cap of the shaft of the focusser to unscrew.
I then had a wheeze. I remembered what the poster on the old thread had said. I need not be concerned that mixing two lubricants together might be the wrong thing to do: The focusser of the binocular presently turned so stiffly that the binocular, as it was, was useless to me (or any friend or family member who I might hand it on to). I was in the "Win, Win" situation that I should either get a working binocular now -- or should I eventually get the end cap off, I should get a working binocular in the future.
I got out an oil pen filled with light machine oil. I found a likely place to add oil where the oil might seep through into the threads of the focussing screw, and a place where it might likewise seep through into the threads of the focussing wheel. I added a few one millimetre diameter drops of oil in each place*. It was then only left to wind the focussing screw many times back and fore, and see if this would successfuly work the oil in. It did!
If I’d continued much longer trying and failing to get the end cap to unscrew, and so getting more and more frustated, I’d almost certainly have ended up butchering the screw slot of the endcap. To boot, should the blade of the screwdriver have slipped, I could have ended up stabbing myself with the screwdriver through my hand.
Stephen
* I should have built up a couple of drops at a time (since too many drops might, irreversibly, have made the focusser move too freely instead of too stiffly), and then thoroughly tested the effect each time. But it was late at night, so I left the final big test until the focusser perceptibly began to turn more freely in the intermediate little tests
As I recall, a long time ago a poster on an old thread, possibly on BirdForum, said that it was his or her practice when relubricating the stiff focusser of an old Porro to add a little light oil to the original lubricant, but otherwise leave the original lubricant undisturbed.
I wouldn’t normally post, but I have never since reading that post read mention of the same practice again.
The spur is that yesterday I was grateful to the poster for describing his practice. I bought a battered old Japanese Porro that looked as though it might be capable of resuscitation. One job of work that was needed was to relubricate a stiff focusser. When disassembling the focusser of an old Japanese Porro, I usually remove an end cap to expose the end of the focusser shaft. I insert a screwdriver down the shaft, unscrew the focusser locknut, and proceed to complete disassembly.
But last night I couldn’t get the end cap of the shaft of the focusser to unscrew.
I then had a wheeze. I remembered what the poster on the old thread had said. I need not be concerned that mixing two lubricants together might be the wrong thing to do: The focusser of the binocular presently turned so stiffly that the binocular, as it was, was useless to me (or any friend or family member who I might hand it on to). I was in the "Win, Win" situation that I should either get a working binocular now -- or should I eventually get the end cap off, I should get a working binocular in the future.
I got out an oil pen filled with light machine oil. I found a likely place to add oil where the oil might seep through into the threads of the focussing screw, and a place where it might likewise seep through into the threads of the focussing wheel. I added a few one millimetre diameter drops of oil in each place*. It was then only left to wind the focussing screw many times back and fore, and see if this would successfuly work the oil in. It did!
If I’d continued much longer trying and failing to get the end cap to unscrew, and so getting more and more frustated, I’d almost certainly have ended up butchering the screw slot of the endcap. To boot, should the blade of the screwdriver have slipped, I could have ended up stabbing myself with the screwdriver through my hand.
Stephen
* I should have built up a couple of drops at a time (since too many drops might, irreversibly, have made the focusser move too freely instead of too stiffly), and then thoroughly tested the effect each time. But it was late at night, so I left the final big test until the focusser perceptibly began to turn more freely in the intermediate little tests