Picture of Cleaning and Repairing an Antique Mortise Door Lock
If you have an older house with knobs that slip, latches that are stuck inside the door, or other minor problems, then you should follow these instructions to remove the lock, dis-assemble it, clean and perform minor repairs.

Step 1: Meet the mortise lock and door knobs.

Picture of Meet the mortise lock and door knobs.
This mortise lock set is installed in a 1930 colonial in the Boston area.

Notice the set screw on the base of the knob on the right. This screw should hold the knob securely to the spindle when you turn the knob.
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JamesJ261 month ago
TranN9 months ago

Do you have a suggestion for a place for replacement keys? Our house came with these, but no keys!

tvodny TranN9 months ago
Online restoration hardware places sell a two key set that works for most locks. House of antique hardware. This worked for me. http://www.houseofantiquehardware.com/old-fashioned-keys-pair-brass-plated-skeleton-keys?sc=10&category=52
chriswren (author)  TranN9 months ago
I don't know where you live, but I found a local locksmith (http://www.commonwealthlock.com/) that carried blanks, so I have to assiume they must be ablw to do something with them. I didn't ask because I wanted to try to mill a master key myself (mostly worked).
TranN9 months ago

Thanks! I went to my local Ace Hardware, some of them carry the antique locks :-) not the brass type they sell at Home Depot.

tafranz1 year ago

anyone know where u can find lockscrews that will work on these

Antiques are fragile and need special care and storage methods in order to ensure they are in perfect working condition and can continue to be used for a very long time ahead. It is better to seek professional advise when it comes to cleaning or repairing them. Else, you might just sacrifice your priceless gems to become useless junk.
KI0DN2 years ago
Excellent presentation. Thank you for showing me something else I may tinker with.
Pat_Maroney2 years ago
This is really neat. I love this kind of stuff, thank you for sharing!
parkwood602 years ago
It appears the code for the recaptcha is broke, as it is not appearing in the reply box, only in the write new comment box...

You can use WD-40, or 3 in 1 oil, or anything you'd like in a mortise lock. The tolerances inside are so huge dust and dirt won't affect it the way they would a modern pin tumbler cylinder. Lots of them have gobs of grease in them from the factory.
parkwood602 years ago
I am having a hard time replying to the comments, but I have fixed just about every kind of these locks and I'm willing to help you do the same.
browne3 years ago
I have a sargent mortis lock 5131 and the leaf spring broke that holds the latch out. Is there somewhere I can find another leaf spring?
jmichaelkel3 years ago
I have this same lockset in a door to a rental unti I am re-habbing. Where can I find a replacement threaded spindle (split halves), interior knob, and escutheon for the knob?
in nova scotia, as recently as a decade ago, rods, crystal and plain brass knobs, even replacement locksets, were available in the nearby hardware store(national chain). there's a kind of lockset that has a push spring, a decent effort can be made by putting the spring from a click pen into them.
chriswren (author)  jmichaelkel3 years ago
Fortunately I haven't had to replace a knob, but I have seen them in nearby antique stores. If you're in Boston there's one on Charles Street, downtown: http://goo.gl/WeqKs

The threaded spindles I've picked up at my local hardware store. If yours doesn't have them try to find one in a neighborhood where there are a lot of houses of the correct age.
Thank you for the response. Unfortunately, I live in northern California and there do not seem to be mnay sources for this old hardware. The old knob looked as if it had been cross threaded on the old spindle over the years and there is a lot of slop in the operation. The cam inside the lockset looks good. The spindle is split in two halves and is threaded There is a small downturn on one end of one half which looks to be some sort of catch at the cam side. The spindle is pretty badly bent which is why I am trying to find a new one. The replacement spindle and knobs which you can get commercially at places like Home Depot will not work. Also, the deadbolt I got to be functional but the small knob which operates it is also badly bent and affects its operation as theknob is turned. It looks like pot metal and I am afraid if I try to straighten it, it will snap. I plan to check a few places out today that I heard of - an antique store and a locksmith who has been around for awhile. If I luck out, it seems I have no recourse but to pull it out and plug or fill the door, then pep it for a current lockset and deadbolt. This would be unfortunate as the door I preserved and the lockset is pretty cool with the ornamentation of the handle and deadbolt.
Yokena3 years ago
I'm so glad I found this site as I just might be able to solve my door lock problem.

I have locks on front & back door marked as "E-Z Mortise", made in Taiwan. They seem to be old and are made of mostly cast iron and brass. It may be that they are a copy of the old Sargent lock as they look very similar.

What I need is the brass cam, as shown in the third picture. The cam tabs are not the same, one being wider. The wider one is worn down to the point it no longer functions.

It I can't find the cam, I suppose I could have a machine shop build up the cam but it would probably cost more than a whole new lock!

Any advice would be appreciated.
vcortlandt4 years ago
Where can I buy one of those springs?

i also need springs--did you find them?--scott
Believe it or not, those metal reinforcing strips that are in most wiper blades will work well sometimes. BTW, it helps to lay the lock chassis down cover-side-up on a table before you take it apart. Take pix of it once you open it so you remember which way everything goes together.

If it's a Sargent Easy-Spring, the hairpin spring attached to the chassis bottom up near the cylinder opening usually goes. You can usually make a spring for it "in place" by using the chassis as a bending jig, but it needs very narrow stock. You can narrow the stock by grinding carefully...just don't overheat it and ruin the temper.

Another thing that goes (in an outside door lock) is the spring in the cam disc that fits in the inside cylinder opening. Not all locks have these, but the ones that do rely on the spring to keep the cam in a neutral position. Otherwise, it can flip down and jam the bolt...usually in the locked position. it's difficult to replace that hairpin spring, so I usually replace the whole disc (found at your local 'smith).

If the lock has a key cylinder, there will be either one or two setscrews holding it in place (sometimes hidden under the edgeplate, or scalp as it's called). If there is only one, it has a LEFT HAND THREAD.

WARNING: Some newer mortise locks (like General and Schlage) have VERY strong springs in them and should only be taken apart with a special fixture that controls the release of the spring tension...or you may end up in the emergency room.
chriswren (author)  vcortlandt4 years ago
I bought mine from mcmaster:

I measured the dimensions of the old springs and tested some under load to calculate the bias and spring constant. Then I used their website to search for close matches.

Thank you............
n_b_c3 years ago
this looks like a good site, so now that i have the answer to my mortise lock question, i,ll add my own tip:have any of you tried this?
we had a pair of big old double doors, with very worn/dropped non ball-bearing hinges. as they were 5 inches by 5 inches, replacements were not easily obtainable without waiting. we swapped the higes from top right to bottom left, and vice-versa. this not only brings the less used inactive door hinges over to the active [more wearing side], but the wear takes place on different surfaces, depending wheather the hinge is installed as left-hand or right-hand. if you draw it out you can see how the wearing points change left to right. it got us out of a sticky situation!--nbc
joldfield3 years ago
I am repairing an older (1905 ish) mortise door lock. I cannot find a way to remove the knobs, there is no set screw, but what appears to be a metal dowel through the knob. Is there any way to remove the knobs without removing the metal dowel as I am not sure about the durability of the lock in general and don't want to damage it?
any experience with a mortise lock that has a set of buttons at the top that allow you to 'lock' the latch portion? that's what i have on my front entry door & now that i have it cleaned up i believe it's missing a part to help keep the spindle housing pieces in place (i have 1 piece with this task at the moment). the coil spring for the latch is actually on a post inside the latch itself, so my guess is i'm either missing a solid metal piece or possibly a leaf spring. my theory that someone LONG ago opened the lock box is somewhat confirmed by the fact that i believe the piece that holds the buttons in place was upside down when i took the lock apart. all the rest of the mortise locks in my house for the inside & side entry doors don't have this feature so i can't easily compare :-( she's a PENN Pat. Nov. 5 1912
lock_front door_clean2.JPG
chriswren (author)  n_toxic_ated3 years ago
Sorry , I don't have any locks like that, but thanks for posting the photo. It's a cool looking lock.

Sounds like dll932 has your back though. good luck!
I saw your note on finding a second lock. Did it have a different latch? The buttons on my lock are just as yours are, but the latch is solid with no spring. The pin that slides in the open space in the right end of your latch is instead linked to the latch.

There is a small leaf spring at the top of the enclosure that pivots the cast half circle and the latch to which it is linked back into the closed position. I can see hardware stores stocking replacement latches and springs when the correctly-sized little leaf springs were no longer available.

I'm not by the computer with the pictures right now, I'll try to post a clear picture later.
here's the 2nd lock i picked up (not yet cleaned). upon closer inspection i see 2 long, flat pieces of metal in the top right corner area, likely a broken leaf spring from somewhere, so who knows if anything else is broken or missing.

i'm also attaching a pic of one of my interior locks (not cleaned either, but clearly didn't get exposed to the weather!) with no coil spring either.
another button mortise lock.JPGinterior door mortise lock.JPG

Glad I live in a dry climate! just spider webs and accumulated dust to clean.

You can see the leaf spring across the top of the enclosure.  It goes under the two-button locking mechanism, which is not sprung (back to original question).

Except for the solid vs slotted latch shaft your front lock and mine look very similar.
dll932 Utemike3 years ago
Looks like your leaf spring is upside down-it should be that lever against the case.
i'm not at home right now so i don't have the lock with me & i don't have pics on my laptop since i haven't cleaned it (yet?) so i'll take a look in a day or so.
You are missing a leaf spring that helps return the latch to the closed position; it runs parallel to the case bottom and pushes the "question mark" shaped piece toward the lock face. It looks like you are missing a hairpin-shaped leaf spring the helps retain the button position. If you want, you can disable the latch portion of the lock by removing the buttons and links. Penn is a very old name in locks, by the way.
chriswren (author)  n_toxic_ated4 years ago
we have that same kind of latch on our front door, but I haven't tried to open it up yet. Sorry.
all's good! i found another mortise lock with buttons at a nearby antique store & after comparing them i realize i'm not missing anything, except perhaps the skeleton key that fits into my front entry door lock (the key i do have fits/works better in the mortise locks inside my house). good luck when you finally take yours apart! (i took one of my inside mortise locks apart afterwards - a mere 7 or 8 removable parts vs almost 20 in my front entry lock!!)
drobinson153 years ago
Any idea where one be able to find a mortise with a 3" setback?

It is labeled as D.M. & Co. from New Haven.
chriswren (author)  drobinson153 years ago
No idea, sorry. I actually misplaced one of mine (packed it up in a bag with some of my tools and set it aside when I couldn't finish the project one day). I was terrified I was going to have to try to replace it. Luckily I found it one day (months later) hanging on a hook in the closet. Whew!
aeray5 years ago
Excellent 'ible! I've restored quite a few of these locksets myself (and even mortised replacement doors to accept original hardware. A good tip that you might add: to remove paint from old hardware easily, put the hardware in a crockpot, cover with water, add a dollop of dish soap ("washing-up liquid" in the U.K. I believe) set the crockpot to low and leave it overnight. Thumbs up!
chriswren (author)  aeray5 years ago
That's an awesome tip! I do a similar thing for tough pans (boil dish soap solution in them to loosen stuff up) but it hadn't occurred to me to try it for paint). The lock on the bathroom door is particularly bad, I'll post back and let you know how it goes.
Paint stripper will work if nothing else will. Make sure there is no paint in the openings where the bolt and latch come out and on those parts themselves. If there is rust, at least take a wire brush to it and blow the dust out.
dll9324 years ago
WARNING! If it's a lock for an OUTER door, the spindle will be in 2 pieces. When you push the button on the lock face the OUTER knob is supposed to lock. If you screw the spindle halves together tightly (rather than leaving 1/2 turn of slop or more) BOTH sides of the door will be locked! Also, the split in the spindle is supposed to be in the vertical center of the lock-pay attention when installing and TRY THE LOCK WITH THE DOOR OPEN.

The usual reason mortise locks stop working is broken springs-one would do well to replace them all, if possible. A good way to clean out the lock body is with brake cleaner spray, followed by wiping with a paper towel. One of the FEW things graphite is good for is lubing the inside of a mortise lock body-if it has a cylinder for a key, lube with WD40 (or similar light spray oil) ONLY-no 3-in-1, no grease, no silicone spray.

Frequently the bolt will be bent from attempts to close the door with it extended. Being brass, they can be CAREFULLY straightened.

Painted hardware can be cleaned with paint remover and/or with a Dremel and rotating brush. The brass can polish up like new, but will have to be varnished or waxed after. NOTE: Some finished were purposely antiqued and won't like that way after polishing!
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