Sinar F - Ball bearing in standard question

[Lee Christopher]

Does anyone know how to remove the little ball-bearing in a Sinar F standard? It's the ball bearing that helps you find and sort of lock the default center setting.

I found that it's actually chewing up what underside of my friend's standard and as a result, moving both front and rear standards laterally is not only a painful process, but extremely rough and imprecise.

I've already smoothened the previous rough edges and cleaned/greased the slots, but the ball-bearing is not helping any.

I found two little grub screws at the back of the frame, but removing these only serves to loosen the small round platform that the ball bearing is mounted in, and that platform doesn't seem to want to budge past a certain point.

Any help is greatly appreciated.

[uhner]

You can download the Sinar F service manual here: http://image2output-support.com/sinar/

I should provide you with the information you need.

[rdenney]

Does anyone know how to remove the little ball-bearing in a Sinar F standard? It's the ball bearing that helps you find and sort of lock the default center setting.

Note that most of the detent balls in the Sinar are inserted on a spring, and will pop out on disassembly if they are clean and well lubed.

The problem is that the detent balls get dirt in them, and won't retract. That digs grooves into the aluminum. One of my F standards (before I replaced it) had a groove caused by this on vertical post for the rise.

The solution is to free up the ball so that it retracts easily as intended. Grease on the top won't do this, because the problem is down in around the ball. You might be able to solve the problem without disassembling the ball. Get some Kroil (from Kano Labs--the best penetrating oil on the planet) and dribble a drop into the ball while depressing it. You may need to press pretty hard to get the ball to retract for this exercise. If you can get it to move at all, the Kroil will almost assuredly allow it to move much more freely. After that, keep it lubed with non-gumming watch oil.

As far as I can tell from inspection and from the service manual, the only way to get the detent balls to come out is for them to be clean enough to do it on their own.

Rick "noting that the ball sizes changed with different models, particularly between F and F2" Denney

[Lee Christopher]

Thanks for the link Uhner, and thanks for the run-through Denny.

The ball bearing does move, but I've just applied some WD-40 (the only penetrant I have at the moment at 1.40am and pressed it down a couple of times. It does seem to move a little bit more freely now, but the rails n the underside of the standards are cut again, so I'll have to smooth it out again.

If you look at the exploded view (http://image2output-support.com/downloads/sinar/View%20Camera%20Service%20Manuals/Sinar%20F%20-%20Sinar%20Handy.pdf), how do I remove the entire carrier (item #10) for the spring and ball bearing? I loosened and took out grub screws #1 and #13 depending on which standard you're looking at, vbut the ball bearinf carrier moves only a bit, the refuses to budge. It feels like it has a latch or some sort of retaining arrangement on the inside.

I'm thinking of removing the entire ball bearing once and for all.

[Lee Christopher]

Apologies, that link came out wrong. It should be: http://image2output-support.com/downloads/sinar/View%20Camera%20Service%20Manuals/Sinar%20F%20-%20Sinar%20Handy.pdf

[rdenney]

There is a groove on the bottom of the standard in which the ball you mention rides. That groove acts as the "straight-ahead" detent for swings. There is a wide spot in that groove that acts as the center detent for shifts, though I think that wide spot is a wear spot not a design on mine. A different ball (#13 on the front standard diagram) provides the detent for tilts. The #13 ball is never exposed to the air unless you disassemble the standard (by unscrewing the tilt lock all the way and pulling out the tilt shaft), and the ball will fall out when you take it apart. That's the ball I thought you were talking about, because that's the one that rides against a flat surface except for the hole that provides the detent.

The ball for the detent on swings and shifts (which use the same control on an F) will chew on that groove. Mine is a bit chewed up, and the lateral shift is a little rough. It's not rough enough to bother me.

That groove is probably a weakness in the F design. I don't see any way to renew that groove except by replacing that part, which is #23 on the diagram on for the 437.31 standard (the front standard for an F).

The first F2 standard uses a steel plate between the aluminum part and the detent ball to provide a detent for swings. The aluminum bar slides on top of the steel plate and doesn't touch the ball, and there is no detent for the shift. They were obviously trying to solve this problem. The second F2 standard separates the swing mechanism from the shift mechanism altogether, with separate locks. If these movements bother you, you might keep an eye out for an F2 standard. I eventually saw one for the price I wanted to pay and grabbed it.

You need that ball in place. Without it, there is no detent for the swing movement, and it will be a pain to restore the standards to perfect parallel when you need to. This will be an annoyance--more annoying than the rough shift movement--with short lenses for the sorts of architectural work you have shown us so far.

Those two grub screws are the adjusters for aligning the detent so that the standard will point straight ahead when in the detent. You'll have to adjust that again.

I've never removed the frame holding the ball, so the one question you asked, I don't know the answer to. My suspicion is that without those grub screws, it just slides out, but it may be lacquered in place. Acetone might loosen it. But if the ball retracts easily against the spring, there is no need to remove it. Just put some oil in there to replace that WD40.

Rick "good luck" Denney

[Lee Christopher]

Thanks for taking the time to go through that Rick.

It's not for my camera, but a friend's. The Horseman I'm using has the sweetest, most precise and repeatable adjustments I've ever encountered on a view camera. Everything, even the non-geared movements feel like they're on hydraulics. :D

Back to the Sinar F: I've taken out the two grub screws entirely (Item #12 and #13 depending on which standard front or rear), and the carrier with the ball protruding (Item #10) rises up by about 1 - 1.5mm on it's own, and stops dead like that.

I've tried gently lifting it with the edge of a knife to no avail. Looking at the diagrams again, the carrier looks to be a half cylinder with no other restraint system below it, so I'm guessing that there might be a very small ledge along the cylinder, or the shaft that the carrier fits in somehow corresponds to a circular transverse plane keeping it down without further screws or pins.

Which leads me to think ... let's take just one set of grub screws - say Item #12. What if I let one out completely and screw in the other all the way?

I notice that a balance of both the left and right grub screw adjusts the 'centering' of the standard, meaning to say, screwing in one grub screw more than the other will rotate carrier #10.

That may rotate the carrier around enough for it to be released.

I'm just guessing ... and I've passed both standards back to my friend earlier tonight so I'll have to wait till a few days later to find out.

The only disadvantage I can see is that visual centering has to be done anytime movements are used, but whether that would end up being more of a problem than a solution is left to be seen.

Would you happen to know if the Sinar P or P2 also use the same materials and ball-bearing system for it's standards? I was thinking of switching to a P2 only because it's about 2kg lighter than my Horseman and I'm concerned if the underside of the P/2 standards will get chewed over time.

Thanks Rick for all your sharing.

[rdenney]

Would you happen to know if the Sinar P or P2 also use the same materials and ball-bearing system for it's standards? I was thinking of switching to a P2 only because it's about 2kg lighter than my Horseman and I'm concerned if the underside of the P/2 standards will get chewed over time.

Given that only the first F has that groove which wears, and all the later F versions don't, I would expect that they understood and solved the problem pretty quickly. Even an F2 would address this problem completely, it seems to me. My F2 front standard does not display any similar characteristic. The later F2's used T-shaped screw that runs inside a T groove in the standard for the lateral shift. There is no shift detent. The earlier F2's do the same thing, except that the T screw is also the rotation shaft for swings, since there is only one tightener for both movements. But the earlier F2 has a steel plate to act as a wear layer for the detent ball, which solves the problem.

The P has all geared movements that are self-braking, and I expect the detents, if there are any, are more fully enclosed.

Rick "never a big fan of those multipurpose standards as a lens standard" Denney

[Lee Christopher]

Thanks Rick, that's reassuring to know in case I do switch. :)