Can we talk about how I used to clean focus rings with lighter fluid in 2011?
I used to dunk every gritty focus ring in a tray of Ronsonol and call it a rebuild, because a guy at a shop in Sacramento said it was the fast way. Last Tuesday I spent 40 minutes pulling a 50mm apart with a lens spanner just to brush out three grains of sand with a soft toothbrush and a drop of naphtha on a swab. The old soak worked maybe 80 percent of the time, but the other 20 percent came back a month later with grease turned to glue. Now I do it dry first, then spot clean, then check the helicoid travel by feel before it ever gets sealed up. My hands hate the slow way but my rework bin has gone from six lenses a month to almost nothing. What do you all use for sand in old rings, brush and solvent or is there a trick I skipped?
That Sacramento trick was everywhere back then and I fell for it too, so I get the shift. My question is about the dry first step you mentioned, because when I try brushing sand out dry, I end up dragging grit along the aluminum threads and scuffing them up worse than the sand would have. Do you break the ring down to bare helicoid before you brush, or are you working it out while it is still partly together? And when you feel the helicoid travel, what are you actually checking for, a rough spot, a tight section, or just even drag the whole way through? Curious how you handle the grease that already turned to glue, since that seems like the part brushing alone will not fix.