Linhof B1 rail extension stuck on

[Jeff Keller]

The black caps on the standard rail have a short plastic threaded male fitting (looks larger than 3/8") that could screw into either end of the standard rail. Your black cap should unscrew easily. The metal cap on yours would have to be on the extension tube and is connected to the rod that extends to the opposite end of the extension tube with the fairly large male fitting that would screw into the main tube.

I would guess that something loosened up or broke on yours. Someone "fixed" it by gluing the extension tube to the main tube. Normally they unscrew very easily.

The rod inside the extension tube is roughly 3/8" in diameter and is smaller than the male fitting that screws into the main tube. Maybe the male fitting came off or just came loose so someone glued everything together. I can't see how the male fitting, the rod, and the knob are attached together. There are fittings inside the extension tube that keep everything approximately centered, and block the view of how it all fastens together.

Both my main tube and my extension tube are roughly 32cm long.


jeff

[Jeff Keller]

Black cap


Extension tube


Main tube

[sharktooth]

The Bi-Kardan main rail has no threaded rod in the middle. It only has screw holes at each end. The black caps screw into them.

The extension rail has a long threaded rod in the middle that acts like a bolt. The bolt screws into either end of the main rail. The head of the bolt is attached to what looks like a black cap. You turn that to tighten/loosen the bolt. There is no cap on the other end of the extension rail. The bolt has a retainer to keep it in the extension rail, so the black bolt head cap cannot be completely removed, it just unthreads the bolt.

Try to unscrew the black cap. If the cap comes off, then that section is the main rail. If it doesn't come off, and is harder to turn, then that's the extension rail.

The 65cm long rail is probably the main rail for 8x10, since that's just over twice the focal length of a standard lens for 8x10. I'd guess that the shiny metal cap is someone's home-made replacement for the regular rail cap that got lost.

[Jim Andrada]

And it's worth noting that the rail sections are keyed into each other so they won't turn unless the threaded rod is loosened. This cap is definitely not a Linhof part. I have 3 Linhof cameras that use the same rail sections. (4 x 5, 5 x 7, and 8 x 10)

Worst case you could cut the whole end of the tube off and detach it, then find a new rail - they turn up on eBay from tie\me to time, or just cut down the threaded rod. I had a rail shortened by a local machinist once who did exactly that so I could squish my 5 x 7 down enough to fit in a Kelty backpack. By the way there is a black cap part that's threaded to fit the end of the rail so it accts as a stop.