Frozen Focus on Mamiya RF

[De_Corday]

Hey all. Working on my first real junk camera, a Mamiya RF that came to me with a loose, free spinning focus ring. I can get the lens disassembled from the front, but that just gets me to the leaf shutter. I can find situate the focus ring in a track where it hits stops at each end of the scale, but when I tighten the grub screws down nothing budges. I have drowned it in naphtha to no avail. There is no give whatsoever. Anyone ever play with one of these before? The focus looks pretty primitive, yet I can't figure out how to get lighter fluid to the helicals...

 

[De_Corday]

As near as I can tell, that threaded part extending out the back is the rear part of the lens barrel. It engages the RF levers inside the body. It's not moving worth a damn. This thread on Mflenses seems to describe the same issue, only solved with use of a butane torch... I'm not above using a torch, or boiling, but I would prefer not to have to disassemble the entire shutter assembly if at all possible...

 

[Landshark]

ditto on the threaded section on the back.

Nothing to lose with a couple drops of penetrating oil(gasp!)

 

[De_Corday]

I used some GT85, some mild penetrating oil I use on stubborn bicycle parts... no-dice. In the past I've had luck with PB Blaster on automotive suspension systems, but that seems *way* overkill for a camera. I'm not even sure exactly where to apply it.

The shutter is getting sticky now, so a total tear-down may be in order.

 

[farlymac]

Have fun with that LVS/EVS (whichever Mamiya calls it) system.Take plenty of photos, and note how all the parts are aligned when they come off.

PF