Cambo/Calumet SC-2 - standards not moving fore/aft

Got out the old Cambo yesteray - found the friction adjustments on the standards aren't working well at all. Turning to move a standard fore and aft just spins the knob (with resistance); I can push the standards while I turn the knobs and they'll move.

Played with the bottom set-screw, no real effect, other than at full tightness it totally locks the standard in place. So I removed the front standard; there's some black crud on the bottom friction roller (the roller that the knob "propels"); cleaned that off with solvent and a q-tip and cleaned the monorail; no help. The two "top" rollers (inside the roller assembly) are really stiff - I can just barely roll them with my fingertips. I drizzled some naptha on each side and they loosened a bit, then got tight again - I assume there's grease or lube in there that's seized up?

If so, I'm guessing I need to remove the allen bolt that connects the roller assembly to the front standard, and remove and clean and re-lube those two upper rollers... am I on the right track? Are they what's putting the brakes on? If I pull that bolt, will springs and gears and shrapnel fly out of there, never to be re-assembled, or is it all very simple? There's also some grease residue on the bottom roller, across the center (doesn't contact the monorail), so it looks like perhaps that was originally greased?

Any help appreciated!

You're on the correct track. Its straight forward mechanical assembly. If a knob on an adjustment has to be pushed in to engage and pops out when released then it has a spring under the knob.

Thank you sir, I'll take it slow with full paranoia!

On the Cambo 25 mm square-rail cameras, the drive roller on the bottom bears against the surface of the rail and drives the standards via friction. Both the OD of the drive roller and the mating rail surface must be clean and free of any lubricant. Otherwise the roller will simply slip against the surface. The top two idler rollers and the top surface of the rail should be clean and dry as well.

The drive roller turns on a shaft that is lubricated with a thin layer of grease where it pivots in the through hole in the standard. Over time, especially if stored in a hot environment, the oil can begin to separate from its thickener and seep onto the OD of the drive surfaces (one on each end of the roller) and then onto the drive surface of the rail as well.

It’s a good idea to disassemble, remove the old lubricant, and install a thin coat of fresh grease to the drive-roller shaft pivots, being careful to clean the roller OD drive surface and that of the rail prior to reassembling the standards onto the rail.

Ian C said:

On the Cambo 25 mm square-rail cameras, the drive roller on the bottom bears against the surface of the rail and drives the standards via friction. Both the OD of the drive roller and the mating rail surface must be clean and free of any lubricant. Otherwise the roller will simply slip against the surface. The top two idler rollers and the top surface of the rail should be clean and dry as well.

The drive roller turns on a shaft that is lubricated with a thin layer of grease where it pivots in the through hole in the standard. Over time, especially if stored in a hot environment, the oil can begin to separate from its thickener and seep onto the OD of the drive surfaces (one on each end of the roller) and then onto the drive surface of the rail as well.

It’s a good idea to disassemble, remove the old lubricant, and install a thin coat of fresh grease to the drive-roller shaft pivots, being careful to clean the roller OD drive surface and that of the rail prior to reassembling the standards onto the rail.

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Thank you - I was unable to disassemble it, the allen key I have is the sort that's fatter than the male-key end, which tapers in - so I couldn't get it deep enough into the bolt (if that's even the proper place to disconnect the big round cap, seems like it). There's also a nut on the far side, where the rectangular sliding cap sits, but it seems like it would take a paper-thin socket to get to that?

What I did find is that the idler rollers were frozen up. I soaked some naptha around those (it was handy, my bromoil brush cleaner); they have some side-to-side play, so breaking them loose with a screwdriver allowed me to spin them and work more solvent in. So I suspect that what I did was "melt" the dried up lube, which means this will likely be a chronic problem as time goes by. But the standards are at least working properly now.

But am I correct in assuming that allen-head bolt is the way to open the assembly up (it's inside the roller block, and points towards the ceiling when the camera is assembled and oriented)? Seems like it would be tough to get out, since there's very little space to get it started (the opening blocks the wrench from having much movement at all). I'd very much like to properly clean and lube the whole assembly, but I can at least get to work now!

Please post a picture of the standard. Some standards require the removal of the standard frame to access the base components.

Here's a pic.

Since no one has made the suggestion yet, I will. Ask Cambo for advice. https://www.cambo.com/en/

The knob should come off first, it may have a center that pops out then a nut that holds it on or it unscrews once the nut is removed.
I may be off line for a few days so i may be slow in replying.

The knob that unlocks the movements? It just unscrews all the way, and there's a washer beneath it. Looks like the allen screw that's hidden when the standard is mounted on the rail is the next step, but I still have to get an allen key that fits in there better to try it. I have a test shot locked in right now so I can't take it apart til I get through that.

Never say never, but I have seven Cambos and not one of them has the standard screwed to the tripod head. The movement is for moving one standard not the entire camera.

cowanw said:

Never say never, but I have seven Cambos and not one of them has the standard screwed to the tripod head. The movement is for moving one standard not the entire camera.

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I wasn't referring to the tripod head or the tripod block and haven't mentioned those parts in any comments, not sure where you're getting that - the standards are at the front and back of the rail. The standards have a plastic knob at the bottom/horizontal part, which locks in the swing. When the knob and washer comes off, the bolt they attach to comes up from the bottom of the standard. When you remove the standard by rolling it off the rail, it looks like that bolt is an allen-head screw that's hidden inside that roller-block thing and holds the rounded top on the roller assembly.

There’s an optical illusion in your post 7 photo.

sorry, my bad.

The disassembly/assembly of the standard to the rail block difficulty arises because there is an M6 x 1.0 nut tightened to the M6 x 1.0 mm-pitch x 50 mm socket-head screw that fastens the standard to the rail block below it. The nut is essentially inaccessible. It is this screw and nut that fastens the standard to the rail block. The head of the screw is on the underside of the rail block and clears the top of the rail in assembly.

The knob (mostly obscured) is seen in the photo atop the side-shift clamp on the horizontal base of the standard. It threads onto the end of the M6 socket screw. There are two greased washers directly below the hub of the knob. These two washers bear against the rim of a steel cup (described below). The knob simultaneously locks the left-to-right shift and the horizontal pivot of the standard. If you enlarge the photo of post #7, you can see the hub of the knob, the two steel washers below it, and the rim of the steel cup resting on the side-shift clamp (textured black plastic).

The nut is recessed down into a steel cup of about 13 mm hole diameter. The distance across the diagonally-opposite corners of the nut are about 11 mm. That leaves about 1 mm clearance between the corners and the ID of the hole in the cup. It gets worse. The nut, at least on mine, isn’t perfectly centered in the cup. That means that at least one of the corners has less than 1 mm of clearance with the vertical wall of the cup.

The wrench size of the 6 mm nut is 10 mm. Where does one get a 10 mm socket with a side wall thin enough to fit into the 13 mm hole of the cup and strong enough to loosen/tighten the nut while holding the screw with a 5 mm Allen wrench from the bottom? The wall thickness of such a socket would have to be on the order of, say, 0.9 mm or less.

There’s one more complication. There is a thin, formed-steel retaining clip of some sort fitted atop the nut with 3 tabs 120° apart that appear to fit into the thead of the screw. I surmise that it is intended to prevent the nut from loosening in use. Possibly, the clip is swaged onto the end of the nut. I can' t tell from the limited view I can obtain.

Obviously, Cambo had an efficient way of dealing with this. I don’t know the answer.

Thanks Ian... looks like I'll just have to soak it clean and get some lube in there as best I can. I've got them moving now, they feel a little tight though. Man, that's an oddball assembly. Wondering if the nut is retained some way, where a socket isn't needed, just the allen wrench? May not be enough clearance to loosen that though. I'll watch for a deal on a spare standard used to experiment on. Both of my spirit levels are dried up, the replacement bubble level is $44 special order, but standards often go for thirty bucks or so, so I may get one just for the bubbles.

Maybe someday I'll get a nice 4x5 with geared movements, but man, the little Cambo has been a workhorse for me, bought it used maybe 18 years ago.

Ian C said:

The wrench size of the 6 mm nut is 10 mm. Where does one get a 10 mm socket with a side wall thin enough to fit into the 13 mm hole of the cup and strong enough to loosen/tighten the nut while holding the screw with a 5 mm Allen wrench from the bottom? The wall thickness of such a socket would have to be on the order of, say, 0.9 mm or less.

There’s one more complication. There is a thin, formed-steel retaining clip of some sort fitted atop the nut with 3 tabs 120° apart that appear to fit into the thead of the screw. I surmise that it is intended to prevent the nut from loosening in use. Possibly, the clip is swaged onto the end of the nut. I can' t tell from the limited view I can obtain.

Obviously, Cambo had an efficient way of dealing with this. I don’t know the answer.

Click to expand...

I am not familiar with the Cambo. It sounds like you are describing an E-clip, like https://www.marshallshardware.com/products/productList.aspx?uid=2-442-449 (or google "E clip"). These usually fit into a groove machined into the shaft of a bolt, and are intended to keep the bolt captive. One can install or remove them from the side with pliers and luck (removal sometimes means the E-clip flies across the room). It sounds like the side may be inaccessible here? There are thinwall sockets, but if it's really hard to get in there, one might be able to jam the nut from rotating with for example a thin screwdriver, while turning the bolt head. However, if the nut is butted up against the E-clip, it is not going to loosen any further until the E-clip is dealt with.

K&S Precision Metals makes a 15/32 x .014 brass tube that will press fit over the 10 mm nut and form fit it enough to remove it. I had a self locking nut in the same place on a Cambo bellows connector. Cost less than $3. Ace Hardware etc. sometimes have K&S Metal displays of 12 inch long hobby metal,.otherwise online.