Cleaning and Repairing an Antique Mortise Door Lock

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.
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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.

Step 2: What's a spindle?

Picture of What's a spindle?
The spindle is threaded to hold the knobs on, but has flats to operate the lock mechanism and to allow the set screws in the knob to hold the knob securely to the spindle.

If the set screws become lose they will allow the knob to turn without actuating the lock mechanism. If your knob is "slipping" try tightening this screw.

Prolonged use with a lose set screw can damage the spindle. If tightening the set screw does not help, you should be able to buy a new spindle at your local hardware store (not the chain with the 16 year old clerk, find the one with the proprietor who is approximately as old as your home).

Step 3: Loosen the set screw.

Picture of Loosen the set screw.
To remove a knob, find the set screw on the base and loosen it just enough that the handle turns freely on the spindle.

Step 4: Remove a knob from the spindle.

Picture of Remove a knob from the spindle.
Unscrew that knob from the spindle. Make sure not to drop it!

Step 5: Remove the spindle from the door.

Picture of Remove the spindle from the door.
To remove the spindle, pull on the other knob with the spindle attached.

If you need to replace the spindle loosen the set screw on this knob, and unscrew the spindle from the knob to remove it.

Reverse your steps from this point to install the new spindle.

Step 6: Free the lock face from any paint.

Picture of Free the lock face from any paint.
Before you remove the lock mechanism from the door, you may want to score the gap around the lock front with a razor to free any paint that may be attached to the metal.

If there is paint on the lock face, then when you remove the mechanism the paint may stick to the lock face and peal off the wood of the door.

Step 7: Remove the lock face screws.

Picture of Remove the lock face screws.
To free the lock mechanism from the door, remove the two screws in the lock face.

Step 8: Pop the lock case out of the door.

Picture of Pop the lock case out of the door.
To extract the lock mechanism from a tight mortise hole, place a small screw driver through the hole where the spindle was and gently push forward to free the lock face from the wood.

Step 9: Remove the lock case from the door.

Picture of Remove the lock case from the door.
The lock mechanism should come freely out of the door.

Step 10: Open the lock case.

Picture of Open the lock case.
Beware that several components inside the case may be attached to springs. If you are not careful when you open the case, you will not get a chance to see how the inner workings are supposed to fit together, or worse parts, may fly off into the far corners of your workspace.

Carefully remove the screw while holding the case together.

Step 11: Freeing the latch

Picture of Freeing the latch
If you need to reverse the latch so that it closes the other way, gently remove the latch while holding the other parts in place, and re-insert it with the angled end facing the other direction.

If that's all you needed to do, reverse your steps from this point to re-install the lock.

However, look at all those cobwebs! Lets continue on to clean the lock.

Now would be a great time to take a photo of your lock mechanism so you can put it back together later.

Step 12: Disassemble the latch mechanism

Picture of Disassemble the latch mechanism
The latch/knob mechanism should not have particularly powerful springs, just be careful not to lose any of the pieces.

Step 13: Disassemble the dead bolt mechanism.

Picture of Disassemble the dead bolt mechanism.
The deadbolt mechanism will have a powerful spring. Press the gate toward the top of the lock mechanism, lift it over the top of the cam on the deadbolt , and gently release the spring tension until you can safely lift the gate off it's pin.

Step 14: Keep track of the parts!

Picture of Keep track of the parts!
I warned you about losing parts, right?

Step 15: Secure the lock case.

Picture of Secure the lock case.
The main lock body should be cast and fairly durable. The lock face is likely brass and is therefore easy to dent and even bend. Use a vise to hold the case body so you can clean the face, but do not over-tighten the vise or clamp directly to the brass face, or you will damage your lock.

Step 16: Polish the brass lock face.

Picture of Polish the brass lock face.
Use 0000 steel wool to polish the lock face. Do not think you are clever and use sand paper to rush the job along. Be patient. Remember you are here because some lazy sod didn't bother ot remove the lock before painting. Look at all the gunk on there! Do not repeat their mistake. Patience!

Step 17: Decide what to do about dings and dents.

Picture of Decide what to do about dings and dents.
You may reveal marks from the craftsman who built your lock. All mine have unique numbers stamped into the faces.

Deep dents or gouges in the brass will resist polishing. You can decide to try to clean them out but I just leave them dark. They add character.

Step 18: Polish the exterior latch and dead bolt surfaces.

Picture of Polish the exterior latch and dead bolt surfaces.
The latch and possibly even the deadbolt will also be polished brass. You can clean them with steel wool in the same way you cleaned the lock face. I don't put them in the vise to polish, I just hold them in my hand.

Step 19: Clean the case and parts with WD-40.

Picture of Clean the case and parts with WD-40.
If you did it right, your lock case will be full of steel wool dust. Clean it and all the other parts with a paper towel and WD-40.

Do not use oil!

Get all the dust, cobwebs, and steel wool out of the case and off the parts.

Step 20: Re-install the deadbolt and prepare the gate.

Picture of Re-install the deadbolt and prepare the gate.
The first tricky part of re-assembly is to get that gate back on with that stiff leaf spring. With the deadbolt in place, reverse your steps: gate on pin, leaf spring against the stop, gently squeeze the gate into position...

Step 21: Attach the gate to the dead bolt.

Picture of Attach the gate to the dead bolt.
...and drop it onto the cam of the deadbolt. Tension should keep it in place.

Step 22: Replace the latch spring.

Picture of Replace the latch spring.
If your latch spring is broken or weak then you'll need a replacement.

You can take the lock to a local locksmith (find the one that's been around since your house was built).

If you have a good spring (maybe in a different lock) you can measure the length of the spring when un-tensioned. Then hang weights from it to determine the amount of force needed to start stretching it (the spring pretension force) and then amount of additional force needed to stretch it a specific distance (the stiffness of the spring) then you can go find one online.  The McMaster-Carr site has a great search engine for springs.

My locks took this spring:  http://www.mcmaster.com/#9654k116

Step 23: Prepare the latch mechanism.

Picture of Prepare the latch mechanism.
The latch mechanism can be tricky since the top of the case normally holds it in place. I put the parts together as much as possible with the spring un-tensioned.

Step 24: Tension the latch spring.

Picture of Tension the latch spring.
I use a screw driver to tension the latch spring and hold everything into place.

Step 25: Use the screw driver to hold everything in place.

Picture of Use the screw driver to hold everything in place.
Notice that the case top is already on the screw driver so I can drop it into place.

Step 26: Close the case top.

Picture of Close the case top.
Once the case is closed, the latch mechanism should stay in place while you tighten the case screw.

Step 27: Test the mechanism on the bench before re-installing.

Picture of Test the mechanism on the bench before re-installing.
Do not over-tighten the case screw or it will bind the mechanism. Test by using a screw driver to actuate the mechanism. If the latch doesn't come back out when you release the screw driver, then you've either over-tightened the screw, or something else is out of place inside.

If you have a key for the lock, also test the deadbolt.

Now is your chance to fix things, if you don't test it until you have it back in the door, you'll be sorry when you have to tear it all back out and bring it back to the bench.

Make sure your latch is the right way too, if it's backward fix it now.

Once you're satisfied, reverse your steps to re-install the lock set in the door. If the case doesn't easily slide in to the door, use a rubber mallet to gently tap it into place. Do not use a metal hammer or you will mar the surface of the lock face. If you do not have a mallet use the plastic handle of your screw driver.

Step 28: Note that there are many kinds of locks.

Picture of Note that there are many kinds of locks.
Note that not all mortise locks are the same inside. I have two kinds of lock mechanisms that look almost identical from the outside but have a slightly shorter face and a slightly shallower backset.

The latch mechanism on this lock is easier to work with because it doesn't fly apart when you open the case.  There's a leaf spring for the knob return and a separate coil spring for the latch return. Also the the spindle cam pushes directly on a combined arm/transit.
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JamesJ2626 days ago
TranN8 months ago

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

tvodny TranN8 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)  TranN8 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).
TranN8 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.

tafranz11 months 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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