I finally figured out a trick for stuck lens helicoid threads

Was working on a 50mm f1.4 lens from the 1970s last month and the helicoid was completely frozen. Tried heat, tried freezer, nothing budged for 3 days. Then this old timer named Frank at the camera swap meet in Portland told me to try a mix of acetone and automatic transmission fluid. He said let it sit for exactly 24 hours and then tap the barrel with a plastic hammer. I was skeptical but it worked like magic... threads came loose with just finger pressure. Has anyone else tried this weird combo or do you have a go-to method for stuck helicoids?

3 comments

3 Comments

christopherwilson25d ago

That thing about the acetone and ATF mixing is something I've heard a few guys swear by, but honestly I'd be careful with that combo. Acetone is pretty harsh stuff and can eat away at some of the older plastics and even the paint or anodizing on those vintage lens barrels. I had a Pentax 50mm that I tried a similar solvent mix on and the finish came out looking blotchy and weird, totally ruined the look of it. For me, a more gentle approach works better - I just use a little bit of isopropyl alcohol and let it sit longer, like a few days, and tap it gently with a wooden dowel. Sometimes you just gotta be patient with this stuff instead of going in with the heavy chemicals. Not saying Frank is wrong, but I've seen too many lenses get messed up from strong solvents to feel good about recommending it.

davis.adam25d ago

The patience method is where it's at for sure. I've got an old Mamiya-Sekor 55mm that was stuck tighter than a rusted bolt on a farm truck. Tried the heat gun and acetone trick and it just made the focusing ring feel gritty and weird after. Ended up soaking the whole thing in isopropyl for about four days, tapping it with a chopstick every now and then while watching TV. On the third day I heard this little click and it started moving smooth again. No damage to the paint or the glass, just needed time. That aggressive chemical approach might work for some guys but with vintage glass you're gambling with irreplaceable stuff. Once you strip that old coating or crack a plastic ring there's no going back.

riley_miller2520d ago

And that's the thing that gets me about the acetone crowd - they treat every lens like it's a hunk of metal but these old lenses have all kinds of weird materials in them. I had a Yashica that had some kind of nylon ring inside and a little acetone woulda turned that thing into sludge. The isopropyl soak method is way safer cause it's not gonna eat through anything unless you leave it in there for months. Plus you can monitor it and see when the gunk starts dissolving instead of just nuking it with harsh stuff right away. The chopstick tapping trick is genius by the way, I've been using a bamboo skewer myself and it gives you way more control than a metal tool would. People forget these lenses were built with different tolerances back then, they need gentle coaxing not chemical warfare.