Bearings Type? (Century JJ 70mm Optical Bypass Rollers)

[Ryan Gallagher]

What grade bearings do I need if I want to service/replace in the optical sound 70mm bypass rollers?

Found a couple that are starting to exhibit a little drag.

Existing are stamped SSR-4ZZ manufactured by NMB. There seems to be a lot to choose from in the SSR4ZZ and SR4ZZ line:

https://www.nationalprecision.com/pr...oduct-variants

Looked in all our parts locations, no spares ATM,

[Steve Guttag]

Remember, with Century...nothing is precision. That doesn't mean you can't use precision stuff but it never had it to begin with. ABEC-1 is going to be fine, particularly for something like a bypass roller. If it fits, it works.

[Ryan Gallagher]

Remember, with Century...nothing is precision. That doesn't mean you can't use precision stuff but it never had it to begin with. ABEC-1 is going to be fine, particularly for something like a bypass roller. If it fits, it works.

Thanks Steve. I was rushing out the door when I posted it the Q. I expect the answer is the same... but to use better terms after looking at parts catalog, I'm actually referring to the large and small dia "film guide roller assembly" that are part of the idle/bypass path within the optical reproducer, not the bypass rollers on the external bypass (which we lack).

I also had the thought that maybe some of the 35mm ones in the mag penthouse are the same bearing? I could maybe swap until i can service or replace the issue ones. We have no 35mm mag capacity in our CP200.

I didn't snag a picture, but to steal one from the archive for illustration. Suspect bearings in Yellow. Possibly available bearings in Green (for now).

rollers.png

[Steve Guttag]

I know what you were referring to. Bypass rollers in the optical soundhead are going to be smallish and, again, low-precision. Other than keeping the film from scratching and guiding the film in/out and around things, they don't really do anything precision. The token lip on the rollers are just to keep the film from walking off as the film is under tension from either the take up reel or platter take up. The bearings are going to be small (the diameter of the rollers are small too).

You'll likely find that the rollers that actually are part of the magnetic sound reproduction are going to be more substantial. Everything the film touches between the film stabilizers becomes a potential source for irregularities. No doubt, the "engineers" at Century used the mass of the rollers themselves as a mini-flywheel to reduce flutter introduced by the guidance.

[Ryan Gallagher]

Thanks. We have 70mm Tuesday (tomorrow). Of course one notices these things as I started to reconfigure the projectors last night.

i have some that should arrive this evening, but not overly concerned, they still turn easily, but lack some of the free spin duration like the other projector. I cleaned some buildup off the flanged cap screw faces, which seemed to eliminate the sensation of rough patches.