Installing Missing Spindle on Old Lock

The spindle and inside knob are missing. I have a newer glass knob and a new threaded spindle. The old spindle broke off inside. My question is how do I keep the spindle end captive at the outside-the-door portion. (I understand the inside spindle end is captive on the knob via set screw.) Thanks!

 

Most that I use both knobs have a set screw. You cut the square spindle to the correct length. Screw on one knob and tighten the set screw. Put it into the lock and screw on the other knob and tighten the screw.

 

Not a knob on each side. There is a knob on inside, which I am fine with. My question is about securing the spindle to the outside where the thumb handle is.

 

Most handleset mortise locks of this era use a split spindle......it's a precarious arrangement that was always prone to loosening. Essentially, it's a square spindle, split in two along it's length, with one half having a slight hook on the lock end, with the other half being normal, without a hook. To install, the half with the hook is inserted first, until you feel the hook engage behind (exterior side) the internal latch hub, then you can insert the non-hook portion along side, until both halves are even. At that point, you can screw on the inside knob until it's almost snug against the inner rose, then tighten the set screw for all you're worth.

There may have been other methods used by some manufacturers, but this was most common, and the only method I ever came across. The bad thing about replacement parts, is that theoretically, spindle dimensions thread pitch etc was the same for most manufacturers, so aftermarket parts were supposed to fit all, but that frequently was not the case, and OEM parts had to be ordered.

 

Also, I don't see a brand name on the lock's edge, and while there's probably a name on the key cylinder which gives us a 95% chance the lock is the same brand, it might help a bit. For example, Yale used a 3-piece spindle that precluded a replacement 2-piece from working very well.

If you remove the lock case from the door, by examining the outer hub, you should be able to see considerable wear if the "Hook" type spindle was used....the spindle being steel and the hub being bronze. With the lock removed, you can also better inspect the fit of any replacement you can find.