Fixed my first Pentax 6x7 with a hammer - don't be me

Used to gently tap stuck lens rings with my palm until I cracked a rear element on a customer's 105mm in Portland last March. Now I just use a rubber strap wrench and a heat gun on stubborn threads - anyone else trash their first expensive repair because you were too stubborn to buy the right tool?

3 comments

3 Comments

emma_wells834d ago

You really think a hammer is the wrong tool for this? I've fixed more stuck lens rings with a rubber mallet than I can count and never cracked a single element. The trick is knowing when to hit it and how hard, not bringing a whole workshop setup. Your palm trick failed because you were too gentle, not because you used impact force. Heat guns can warp the helicoid grease or even the aluminum barrels if you're not careful, and strap wrenches slip on tapered rings. Sometimes a sharp, controlled tap is exactly what those old threads need, you just have to commit to it and not half-ass it.

phoenix_singh254d ago

Honestly, the real issue is nobody's talking about how Pentax put those insanely tight tolerances on the 6x7 stuff. A sharp tap works fine on a Mamiya or a cheap Chinon, but those Japanese threads from the 70s were designed to be a permanent press fit. Your mallet trick just redistributes the force into the barrel itself instead of releasing the thread lock.

val_shah3d ago

Question - has anyone checked if your specific Pentax 6x7 body was built during that weird 2-year window when they switched from brass to aluminum helicoids? @phoenix_singh25 is right about the tight tolerances, but the real issue is that brass and aluminum expand at different rates under heat, so your heat gun trick might actually make things tighter on certain serial numbers. Most people don't realize Pentax quietly changed materials mid-production without updating service manuals.