Found a fix for stuck focus helicoids on old M42 lenses without disassembly

I had this Super Takumar 50mm f1.4 that was totally seized up, wouldn't turn at all. Spent like 3 hours trying to get the front ring off to clean the helicoid threads but the thing was just stuck solid. Then I tried something random, I heated the lens barrel with a hair dryer on high for about 2 minutes and then stuck it in my freezer for 10 minutes. The thermal expansion and contraction loosened the old grease just enough that I could work it back and forth gently. After that I dripped a tiny bit of lighter fluid into the gap and now it focuses smooth as butter. Has anyone else tried temperature cycling to free up stuck threads on vintage glass?

2 comments

2 Comments

emma5221mo ago

Ngl that thermal cycling thing is clever but I'd be careful with the freezer part. I wrecked a Chinon 55mm once cause the cold made the glass elements contract faster than the metal barrel and it actually cracked a cemented doublet. Hair dryer is safer than sub zero temps for sure. Next time try just the heat gun method with some naptha dribbled in while its warm, the solvent seeps way deeper when the metal expands a bit.

val2231mo ago

Honestly that thermal cycling trick is genius, it's the same principle that gets stubborn jar lids loose or unsticks rusted bolts on old cars. I've done something similar with a seized up M42 Helios 44 that wouldn't budge after sitting in a damp basement for years. Put it in a ziplock bag and dunked it in hot water for a few minutes, then let it cool down slowly on the counter overnight. Worked a treat, the old grease just softened up enough to let me work the focus ring back and forth without any damage.