Fixing a mortise lock

[bjclinger]

Hello all,

I am trying to repair a mortise lock on the front door of my 1912 duplex, unfortunately I am stumped as to how to get the handles off the door!

The interior door knob looks like it had a place for a set screw, but there isn't one there now. The exterior is a push latch and I have no idea how it is connected to the mortise lock.

Here is the interior doorknob and close up of set screw:





And the exterior latch, as a side note I was able to remove the lock above the latch, shows a patent date of 12-10-11 and when I showed it to my sister her first thought was that it was only 5 years old



I thought I would look here for advice first, before I call out the locksmith, any help is appreciated!

[Gothichome]

The door knob should pull off as expected, I suspect at the time the set screw fell out the knob was forced over the square shaft. I suspect it will take a little fenagalling and maybe a little leverage to get it off. As far as the thumb latch side I realy can't offer any hints. Nice though to see you are keeping the building as ariginal as possible. That must be tough as a commercial rental building. Having to maintain the period integraty while meeting modern fire codes ect.

[Texas_Ranger]

Is there another hole in the base of the knob? Older hardware often used simple cotter pins (or cut nails) rather than set screws. You can just tap them out using a blunt nail or thin nail set.

[bjclinger]

@Gothichome

I will try to pull the knob off when I get home tonight, we'll see if all that's allowing it to stay is habit.

As for maintaining the duplex, it is surprisingly not too bad. It was built as an up/down with two staircases and it has been owner occupied for about 90% of its history. Other than 2 kitchen and 1 bathroom remodel everything has been maintained as original. Worst part is slowly reglazing the 100 windows in the house, which will likely take me many years to do.

@Texas Ranger

Nope, there is not a hole on the other side for a pin.

Thank you both for your advice!

[phil]

sometimes they have a square threaded shank with a set screw so you can tighten it enough to get enough clearance so it moves but you don't want a lot of axial movement. once you tighten the knobs together the correct amount then you can lock it with the setscrew.

I'd have a closer look to see if it looks like a set screw with a rounded off head or if it is something else. If that knob frustrates you you might see if the other knob will come off easier. It'll likely come apart if you get either knob off. maybe one side is pinned but if it's pinned you should see evidence of a hole right through it not a blind hole. usually they use set screws with a flat head but people get lazy about finding a screwdriver that fits properly and round off the screw.. but if it's a screw it should still look like one even if it's buggered up. Ive never seen them pinned on. perhaps the knob intended to be for the outside was made harder to remove than the indoor one to prevent people from being able to unscrew it and it isn't necessarily put together the intended way.

it's also possible that someone lost the setscrew and replaced it with a longer screw, perhaps one with a hex head. if they proceeded to tighten that one so much they snapped it off. If that's the case you might see evidence of the end of the screw being twisted off.
drilling a tiny hole in it in order to use an "EZ out" is difficult because it's such a small screw and if it is twisted off the end won't be flat. hopefully that isn't the case. If it is you might be able to use a dremil with a tiny cylindrical shaped stone to flatten the end of the broken screw to then get a center punch mark to then drill the screw out with a tiny bit. otherwise the bit will wander. it's a tricky job if that's the case you might find a locksmith.

another trick that you can consider if it is a snapped off screw. If you have a stick welder sometimes you can stick the electrode to the the end of the screw ( like what happens if you don't initiate the arc properly) Once you have the rod stuck to the screw you can turn the rod. this would be very tricky and only perhaps a last resort but I have seen it work in certain tricky situations. It can easily go sideways and you could make matters worse quickly by turning it into a melted mess. a good welder might be able to have better success at sticking his electrode to the end of the screw. an insulator like a straw or tape or something might help stop the arc from wanting to go toward the brass part.

try to unscrew the two knobs from each other and make observation if there seems to be any wiggle between the shaft and the two knobs. If you mucked up the threaded shaft that's easy to replace but try not to mark up the knobs even if you have to make swiss cheese out of the square threaded shank with a drill bit through the screw hole. you might be able to weaken this shaft enough by drilling it to snap it off but again this is a worst case scenario and a method that could go all wrong.

maybe study it a bit more and try to decide if that's a screw head or a broken end of a screw or what. See if the other knob will remove easier. you can try holding one knob and trying to unscrew it from the other. if the setscrew isn't' too tight it might surprise you and just come apart.

one final solution if it is a broken screw. You can take a dremil with a disk, the kind that are about the size of a penny. Use the disc to make a slot in the end of the screw. then you can use a screwdriver to remove the screw. In doing so your spinning disc will make a little cut in the skirt of the brass part near your screw hole You could later fill that damage with solder to repair it.

there are a few ideas. Now I'd just observe what you can and try to think through the best approach. You did well to walk away from it for a bit rather than to become rough with it in frustration . that's easy to do because these things can be challenging

[phil]

I got it a little wrong in thinking there would be a knob either side and when I reread it ,, you did say you have the latch on the outside not another knob.. oh well you can consider the other ideas. Phil

[bjclinger]

I was never able to get the door knob off myself, I was able to jiggle the lock enough that jamb came free, at least for a few months... then it stopped again working from the outside.

Ended up calling the "good" locksmith in town. Had a week waiting list for non-emergency residential repairs.

70ish year old showed up Saturday morning and said " well I haven't seen one of these on a house before"

Turns out the door knob is a two part contraption. The knob screws into a collar which in turn is screwed to the spindle. It took a few carefully placed wacks to break the bond between the knob and the collar and a few more to remove the two piece spindle.

Door knob and collar removed



Two part spindle



After that it was simple to pull out the mortise lock, disassemble and remove two set screws that had fallen inside and jammed the whole mechanism. It was a classic $10 for the taps, $110 for knowing where to tap.