Century JJ Studio Guide Screws

[Ryan Gallagher]

Anyone know the thread pitch and length of the Century JJ trap studio guide screws?

Item 15 on the 70mm trap exploded view:
SC-0054 "Mounting Screw"

One of our traps lacks the mounting screws, and would rather not steal from our 35mm traps when needed each time.

[Mark Gulbrandsen]

I always left the guides off, with the lateral guide roller aligned properly, there really isn't a need for them. Also, I always ran a 35mm VKF sprocket during customers 35mm film runs. The sprocket can be changed without pulling the movement out. As for those screws, they are likely 8-32 x 1/2, I don't think they are 6-32, or 10-32..

[Ryan Gallagher]

I always left the guides off, with the lateral guide roller aligned properly, there really isn't a need for them. Also, I always ran a 35mm VKF sprocket during customers 35mm film runs. The sprocket can be changed without pulling the movement out. As for those screws, they are likely 8-32 x 1/2, I don't think they are 6-32, or 10-32..

Well we were setup without the studio guides previously for 70mm... but had to resort to them on at least one projector for the last mag print. TBD if that problem lay elsewhere and remains, but the guides were the quick fix. I'd like to at least have all my screws for when and if that re-occurs with both projectors. ;-)

[Ryan Gallagher]

I always left the guides off, with the lateral guide roller aligned properly, there really isn't a need for them. Also, I always ran a 35mm VKF sprocket during customers 35mm film runs. The sprocket can be changed without pulling the movement out. As for those screws, they are likely 8-32 x 1/2, I don't think they are 6-32, or 10-32..

Speaking of Lateral Guide Rollers. How easy should these be to adjust? I had one off for cleaning today while checking things, cause it was being a bit stubborn to roll, and it's sprung section was resistive too. Seems better now but the shafts that capture the roller were very difficult to move with the set screw out. Should I push those shafts all the way out and clean in there too, bit of oil perhaps?

It's "fine" except that I feel like if (okay not if, but when) I were to re-do the guide roller alignment in the projector like you are supposed to, I wouldn't be able to get them to budge in situ.

[Mark Gulbrandsen]

I had a Century 35mm factory gauge I bought from ORC when they owned Century. It was very different from the 35mm Lavezzi gauge which was just a flat piece of metal. I'll try to draw what the Century gauge looks like and post it. Anyway, a friend that had a shop with extensive grinding facilities made me a 70mm version by upscaling the width of the 35mm gauge. BTW, the Century Projector operation at ORC was small compared to what Strong set up in Omaha after they bought it from ORC. That ORC plant also made Xenon lamps, so it was interesting to see that operation as well.

[Brad Miller]

If you are going to do anything with the lateral guide roller, absolutely make SURE you get yourself a one-piece molded plastic bin (like a lunchroom tray) to do this in on a table with good lighting. When you loosen one of the two ends, it is unbelievably easy for one (or both) of the the little ball jewels to fall out and if you aren't doing this surgery over a molded container...you're screwed because finding that tiny thing will be next to impossible.

Assuming the alignment is spot-on before you start and it's just the roller isn't spinning and snapping open and closed easily, just know you can also create all kinds of new problems. You could end up with a scenario where the studio guides cause the film to buckle, which in turn will cause focus issues or emulsion scratching down the center (the film scraping against the aperture plate). You can also cause emulsion scratches on the left or right edge of the image due to the trap bands intruding into the edge at the entry of the gate. The slight change in alignment could also have the film dragging slightly diagonal through the gate creating excessive wear, lateral weave and sprocket edge damage on the intermittent. Also if you don't get it back in the exact same position (and I mean EXACT), your apertures will all be off laterally in one direction.

[Ryan Gallagher]

If you are going to do anything with the lateral guide roller, absolutely make SURE you get yourself a one-piece molded plastic bin (like a lunchroom tray) to do this in on a table with good lighting. When you loosen one of the two ends, it is unbelievably easy for one (or both) of the the little ball jewels to fall out and if you aren't doing this surgery over a molded container...you're screwed because finding that tiny thing will be next to impossible.

Assuming the alignment is spot-on before you start and it's just the roller isn't spinning and snapping open and closed easily, just know you can also create all kinds of new problems. You could end up with a scenario where the studio guides cause the film to buckle, which in turn will cause focus issues or emulsion scratching down the center (the film scraping against the aperture plate). You can also cause emulsion scratches on the left or right edge of the image due to the trap bands intruding into the edge at the entry of the gate. The slight change in alignment could also have the film dragging slightly diagonal through the gate creating excessive wear, lateral weave and sprocket edge damage on the intermittent. Also if you don't get it back in the exact same position (and I mean EXACT), your apertures will all be off laterally in one direction.

Thanks Brad. I was doing that over a tray. Both pins that hold the roller in place were quite tight in their holes, as such I only shifted one of them to get the roller out, and the other one remained the index one when restoring it. How much side to side play should remain when reseated between the jewels? I matched the play to the other trap which spins excellent, but play may not be desirable here at all.

My concern about if they have to be re-aligned now was due to the projector manual stating to do it in the film compartment with a piece of film, and in that situation they would be too tight to move by hand in their current condition. Mark also revealed there exists a factory spacer tool for doing this alignment too. So maybe caused more problems by touching it, but non-turning non-springing seemed like a bigger problem. The bulk of the friction seemed to be grime buildup in hard to reach places. Assuming I get it aligned again (or it is still aligned), i'll be more hesitant to take that approach to cleaning it going forward. We already had one projector exhibit weave issues with these traps prior... so going down the alignment rabbit hole eventually seems on the todo list sooner rather than later.

[Randy Stankey]

If you are going to do anything with the lateral guide roller, absolutely make SURE you get yourself a one-piece molded plastic bin (like a lunchroom tray) to do this in on a table with good lighting. When you loosen one of the two ends, it is unbelievably easy for one (or both) of the the little ball jewels to fall out and if you aren't doing this surgery over a molded container...you're screwed because finding that tiny thing will be next to impossible.

There's an old timer's trick for working on small parts, like on guns, cameras and other things with small parts that can go flying.

Get a paper shopping bag or a small cardboard box and place it on the table with the opening facing you. Work inside the bag/box so that any small parts that happen to go flying will be caught.

I have used this trick several times and it has saved me hours of crawling the floor on my hands and knees, looking for tiny parts.

We all knows Murphy's Law #128... The smaller the part, the farther it rolls if you drop it!

[Mark Gulbrandsen]

I've used plastic divider boxes since the late 70's when I worked at Canon where they were using them. They come in all sizes, and they are cheap... I still repair AE-1's and A-1's if anyone needs one looked at!!

[Ryan Gallagher]

I've used plastic divider boxes since the late 70's when I worked at Canon where they were using them. They come in all sizes, and they are cheap... I still repair AE-1's and A-1's if anyone needs one looked at!!

Funnily enough, I may take you up on that one day. I have one with the squeak, but it's not urgent cause I have a good one. ;-)