Have you checked salvage yards for replacement doors? I was able to find mine for $35, including a doorknob and frame. All I had to do was repaint them.

good luck.

well...wait! You can get either salvaged or new mortise sets for $20 or less. Most likely, the little piece of spring steel that makes the mortise go has snapped--if you're mechanical, you can fix it yourself.

Yes, ebay is your friend. You can buy simple mortise locks all day for about 10 bucks; ones with solid brass faces are about double; remove one, study its characteristics and match it; ask the seller for the faceplate dimensions and backspacing if not given.
If the knobs are loose, that's another simple fix, and again, ebay is your friend, for knobs, spindles and setscrews.
Casey

"Our problem is in the door knobs - the mortise locksets do not work well - the knob turns on the spindle no matter what we do."

Are the set screws missing?

There is a set screw on each knob shank that prevents the knob from rotating on the square shaft.

The corners of the shaft are threaded, but the set screw bears on the flat sides.

Replacement shafts are available if one has gotten worn to round.

A real hardware store is more likely to have the set screws if they are missing.

A little bit of low strength Loctite will keep the set screws tight in the knob nut allow dis-assembly for repair.

Please hang in there with this. It sounds very frustrating and seems you still have a little ways to go on the learning curve, but it's worth it. Previous owners got frustrated with the mortise in my front door and had it drilled for a tube lock. OMG, getting the gaping round hole filled and the door re-mortised, and then finding hardware to cover the ugly hole, was so hard.

There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper. -- John Ruskin.

The above is true of tube locks versus mortise locks. You wouldn't trade in quartersawn oak for plywood; replacing mortise with tube latches is a similar downgrade.

Can you post a photo of what you're dealing with? Not that I'm an expert, but someone here may be able to help. You'd have to open an account on a free photohosting site such as Photobucket, upload your photos to your album there, and then copy the HTML tag from photobucket to the body of your message here. The photo will show up when you hit preview.

But even if you can't, I'd say that if I were you, nothing would induce me to replace those doors, even if I ended up with holes in them. But I agree with previous posters - there is enough old door hardware out there that there should be no need for that.

KarinL

everything brickeyee has said is right on target. It's a common problem.

thanks all-- I'm going to try to find new set screws. We are not missing any, but they are not doing their job for some reason. I'll also make sure the spindle isn't worn round.

In the meantime, I just hope no one gets stuck inside my powder room! ;-)

When you tighten the set screws make sure they are on the flat of the shaft and not a corner.

They are a weird thread but I purchased the die (and a spare) long ago and make them from brass rod as needed.

The set screws I encounter most of the time are 9/32-32 with a slot.

The smaller diameter screws with 10-24 threads are for shafts that are cross drilled with threaded holes to lock the knob, not really a set screw anymore.
The head is usually 1/4 inch diameter with an oval style.

just so I understand(and I make sure that there wasn't some crazy change in mortise locks between 1889 and 1922)...when you turn the doorknob, it just spins, but the latch-a-ma-bob doesn't go back into the door?

If you take the doorknob off the spindle, you have a square spindle, and if you turn that, your latch-a-ma-bob goes back into the door?

If the case is that you can turn the spindle and the latch moves, then the problem (I would think) is a contact problem between the doorknob and the spindle...at which point, you would need to inspect the spindle, the screws, and the doorknobs, all of which are pretty easy and cheap to replace (and fairly universal in size).

*MY* problem is one piece of metal that breaks in the mortise itself, a tiny piece of spring steel. If I got industrious I could re-engineer it and fix them all--all my upstairs ones but one are broken. A previous owner went around this by putting barrel latches or hooks and eyes on the insides of the doors (which means the doors lock too, which is nice), so I haven't really worried about it. The doorknobs and spindles are fine, but the guts don't turn any more.

"*MY* problem is one piece of metal that breaks in the mortise itself, a tiny piece of spring steel."

Is it the spring that throws the bolt out (and also turns the knob when you release the knob)?

Does the bolt throw correctly when the knob is turned (both in and out)?

It probably needs nothing more than a new spring of the same type.

Tiny leaf springs are actually not that hard to make.

I have used pieces from a broken electrician's fish as the raw material to repair plenty of locks over the years.

Heat a spot red hot, bend over to create spring, throw in motor oil to cool.

If you heat and cool quickly enough there should be enough tempering for lock springs without much more work.

There were a few atypical locksets made in the 1880's that did not use a square spindle; Niles patent and Gilbert's patent are the only two I know of.
Rarely, the knob proper becomes loose from it's mounting boss so that is spins uselessly. If that was the case, some kind of glue, solder or cement may fix it, but it would be best to find a replacement.
Casey

Here is a link that might be useful: GW discussion of oddball lockset; Niles/Gilbert

"Rarely, the knob proper becomes loose from it's mounting boss so that is spins uselessly. If that was the case, some kind of glue, solder or cement may fix it, but it would be best to find a replacement. "

This is one of the very few lases the instant glues work well.

A relatively tight joint and sufficient area, and low forces.

They are even available in different viscosities to allow them to get into small spaces.

Yes, Brickeye--my issue is that some of my doors have a piece of spring (steel, I assume) in them that is shaped like this:
7 that throws the bolt out. in some, it's shaped like this:
/ \ 'cause it has broken over the years.
I thought "I could take apart an old clock and make lots of:
7 7 7 7 7 all day long" but I have lots of pressing needs, and someone put hooks and eyes or barrel locks on all the doors that don't work so it's not a pressing issue...