Mamiya 7 - Replacement rangefinder adjust screw?

tomfrh · May 3, 2016

My mamiya 7 rangefinder horizontal screw has a slightly worn slot and I'd like to replace it.

The screw is a small threaded rod, with a rounded end to push the mechanism, and a flat head screw slot.

Any idea where I might find such a screw? Does mamiya offer them?

tomfrh · May 3, 2016

The issue is that the head is bad enough that I don't dare apply loctite, as I don't think I'll get the screw out again. The previous owners loctite efforts are what made it so hard to remove. It took a lot of acetone and coaxing to loosen it, and not without further damage.

paul ron · May 3, 2016

Cut a new (or deepen) slot with a 52TPI razor saw.. AKA fret saw.

Dan Daniel · May 4, 2016

Do you have a repair manual with a parts list? It should give the threading of the screw. Or find a thread gauge set. Use calipers to measure diameter of the rod. I've never seen this part, but it sure sounds like a set screw- http://www.winkfast.com/flat-point-slotted2.html
That site's threading is generally called 'coarse' so it probably won't fit for this use.

If you can't find a Mamiya part or an off-the-shelf replacement, you could make your own from threaded rod or by cutting the head off of a bolt and doing as paul ron says, make your own slot. Or maybe a slotted bolt would fit as long as the head wouldn't bottom out? (again, I don't know the mechanism)

tomfrh · May 4, 2016

Yes, it's one of those - a "set screw". Thank you! This helps a lot.

I'll measure the diameter and pitch.

tomfrh · May 4, 2016

APUGuser19 said:
Well it's not "slight" then.

"Slightly worn" as in $@*

paul ron said:
Cut a new (or deepen) slot with a 52TPI razor saw.. AKA fret saw.

Cheers, I'll investigate this if I can't find one.

Dan Daniel · May 4, 2016

By the way, here' a page showing the difference between coarse threading and fine threading. There is mention of extraf-fine threading, but no chart-
http://www.engineeringtoolbox.com/metric-threads-d_777.html

And camera manufacturers can make any thread they want, so you can't always find an off-the-shelf replacement.

tomfrh · May 4, 2016

The set screw appears to be an M1.6 x 5mm, coarse thread (0.35mm pitch). This is a standard size, so I'll buy one and see if it fits.

Mamiya 7 - Replacement rangefinder adjust screw?

Privacy & Transparency

Privacy & Transparency