Minox repair: The film feeding mechanism

tjwspm · May 26, 2024

The 8x11 Minox uses unperforated film. Today this has the big advantage that you can make Minox films yourself from standard 35 mm film. However, the lack of perforation requires a special design for film transport.

When this mechanism fails, the negatives on the film look like this:

The photos overlap because the distances during film transport are not correct. Instead it should look like this:

Two questions arise
1. How does the film transport work with 8x11 Minoxes and how are the equal distances between the photos achieved?
2. What could be the problem and what can I do if the negtive spacing on my Minox is not correct?

Since I had this problem myself with a Minox A IIIs, I have put together everything you need to know how to fix it here:

Incorrect film feeding

It happens that the Minox film feeding works incorrectly, resulting in the negatives overlapping on the film. Learn here how to fix it.

moments-of-now.com

I didn't write this article just as a repair guide for those who are affected. Rather, it is also a concrete description with pictures and videos from the inside of the camera of how this ingenious mechanism in the Minox actually works.

I am particularly grateful for any tips on incomprehensible or missing information!

qqphot · May 27, 2024

Thomas, this, along with the rest of your guides, is superbly written and gives a real understanding of how the mechanism functions. Thank you for taking the time and doing the work of preparing this!

guangong · May 27, 2024

Fantastic detailed description and illustrations. Externally so simple, but internally so complex. During my college days, Minox cameras were on display in jewelry store window. Very expensive, now we know why!

tjwspm · May 29, 2024

Thank you both for your feedback. It certainly encourages me to keep writing on this topic.

tjwspm · May 29, 2024

Added the chapter "Film spool disasssembly" to the article

ic-racer · May 29, 2024

In most of the one's I have seen with poor spacing, the wrap-spring clutch was slipping.

tjwspm · May 30, 2024

ic-racer said:
In most of the one's I have seen with poor spacing, the wrap-spring clutch was slipping.

That's very interesting! But I'm not sure if I understand you correctly. Which part do you mean exactly? Is it one of these:

tjwspm · Jun 1, 2024

Have you ever wondered why some Minox film cassettes have a different spool diameter? I have now included this information in my article under the chapter "The mystery of the 15 exp. spool":

https://moments-of-now.com/incorrect-film-feeding/#The_mystery_of_the_15_exp_spool

Patrick Robert James · Jun 5, 2024

ic-racer said:
In most of the one's I have seen with poor spacing, the wrap-spring clutch was slipping.

I'd love to know what that is. I have one that occasionally double exposes or overlaps. I thought it was just film sticking but the clutch sounds like the culprit.

tjwspm · Jun 5, 2024

Patrick Robert James said:
I'd love to know what that is. I have one that occasionally double exposes or overlaps. I thought it was just film sticking but the clutch sounds like the culprit.

The claw may be slipping because the spring is not properly seated in the housing. The end of the spring (see picture) must engage in the drill-hole of the housing.

AZSkip · Jun 18, 2024

Interesting.

I have a Minox B, absolutely ingenious work of art.

Thank you for sharing your knowledge.

ic-racer · Jun 21, 2024

tjwspm said:
That's very interesting! But I'm not sure if I understand you correctly. Which part do you mean exactly? Is it one of these:.....

Yes this part circled. I just wound up just cleaning mine and it worked fine, but there is special oil for sprag-clutch one-way bearings, I wonder if that would work on a slipping wrap spring clutch.

tjwspm · Jun 22, 2024

ic-racer said:
Yes this part circled. I just wound up just cleaning mine and it worked fine, but there is special oil for sprag-clutch one-way bearings, I wonder if that would work on a slipping wrap spring clutch.

View attachment 372603 View attachment 372604

Thank you for your hint!

I would not recommend any lubrication of the two springs at all. Reason in my article, see below.

Only the bearings should get lubrication. But I would not recommend the HUDY oil for the following two reasons:
1. The oil is intended for high-speed parts and is therefore "super thin". The film spool drive is an extremely slow-moving part. It is also easy to disassemble and the parts can be lubricated separately. So it is not necessary for the lubricant to flow into hard-to-reach corners by itself.
2. The ability of this oil to creep everywhere is actually a danger here. We are very close to the lens here and we want to avoid oil getting on the lenses at all costs.

I would therefore recommend a grease. I use GunCer gun grease (Ballistol) for slow-running sliding pairs with emergency running properties. Because of its very good adhesion, even at high temperatures, it is also suitable for use near lenses and shutters, as the risk of migration into these zones is low.

Thank you for pointing out that the film spool drive is a freewheel. I forgot to mention that in my description. That's why I've added a new little chapter about it here: