Film scratches: how would you smooth out rough rollers?

How would you solve this problem?

This is a 6x9 Graflok Horseman back:



These two rollers are the only thing I can see in this back that touches the emulsion side of the film in the picture area.

Film result:

The rollers spin free, no resistance?

Chuck1 said:

The rollers spin free, no resistance?

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They do spin but there's a little resistance. Should I put a drop of oil on the points they're seated into?

Can you feel anything on the rollers?
Before I'd oil them, I'd try and clean them.
Are they removable? Am I seeing threads on the ends of the rollers?

Bob Merlin said:

Can you feel anything on the rollers?
Before I'd oil them, I'd try and clean them.
Are they removable? Am I seeing threads on the ends of the rollers?

Click to expand...

Good thought, they do have flathead screws on the sides so they must be removable.

Yes I can feel some roughness when I touch them.

Clean with something like a scouring pad and soap?

If cleaning with a solvent like isopropyl or naphtha doesn't remove the rough spots, I would try a mild abrasive--you don't want anything that might make the surface rougher. Maybe some cerium oxide, if you can get it.

loccdor said:

Good thought, they do have phillips head screws on the sides so they must be removable.

Yes I can feel some roughness when I touch them.

Clean with something like a scouring pad and soap?

Click to expand...

Metal polish. At minimum, 2000 grit sandpaper if you want (auto supply- finishing supply), then metal polish. Most likely just going the full length of the rollers while slowly rotating will knock down the burrs. Can even put polish on the sandpaper as a preliminary.

Kitchen scouring pad will scratch. Scotch Brite green is used to add grain to stainless steel, not polish it!

Dan Daniel said:

Metal polish. At minimum, 2000 grit sandpaper if you want (auto supply- finishing supply), then metal polish. Most likely just going the full length of the rollers while slowly rotating will knock down the burrs. Can even put polish on the sandpaper as a preliminary.

Kitchen scouring pad will scratch. Scotch Brite green is used to add grain to stainless steel, not polish it!

Click to expand...

Many thanks for the wisdom!

I wouldn't put oil inside the camera, particularly on parts you can't remove to clean the oil away again. Wet-n-dry paper would be better than sandpaper, and Micro-Mesh would be better than wet-n-dry. Start with a coarse grade and finish with a fine grade, polish with a metal polish afterwards. Test with your wife's finest denier tights (or stockings) by rubbing them across the rollers and if they snag you've still got a burr. Then explain everything to your wife as best you can.

Dan Daniel said:

Metal polish. At minimum, 2000 grit sandpaper if you want (auto supply- finishing supply), then metal polish. Most likely just going the full length of the rollers while slowly rotating will knock down the burrs. Can even put polish on the sandpaper as a preliminary.

Kitchen scouring pad will scratch. Scotch Brite green is used to add grain to stainless steel, not polish it!

Click to expand...

Sandpaper see above, but must work in the direction of film movement, especially on the rollers.

How much resistance is there to advancing the film? I ask because the straight lines shown in the positive photo in post #1 look like stretch marks (some writers used the term “cinch marks”) that I have seen in some photo books from the 1960s and 1970s showing example photos, particularly the books by Andreas Feininger.

These are caused by roll film being drawn too tightly due to pinching of the film in the transport path so that it can’t advance freely. The lines are little cuts in the emulsion from tiny particles adhering to the film.

If the film advances freely and the rollers are clean and reasonably smooth, then this analysis fails.

https://www.google.com/search?q=fil...G4B9IUwgcHMC4zLjcuOcgHlgGACAA&sclient=gws-wiz

True cinch marks occur between over-tensioned coils of film on the supply spool—usually not where the film goes over a guide roller. It would take a a great deal of resistance to advancing the film to cause cinch marks. But a roller could be involved if its bushings were significantly jammed making it almost impossible to turn freely.

@Ian C thanks, the film back doesn't seem over-tensioned, it's less tensioned than my Kiev 6C which doesn't get the scratches. Turning the film advance knob is a relatively smooth ratcheting, no real struggle.

I think it's a combination of the rollers being rough as well as the pivot points they spin in being slightly corroded. I'm pretty sure it's the first film run through this in a number of decades...