doorslock
I want to replace the lock but want to keep using all the existing holes in the door.
Photos here: https://imgur.com/a/wxeoKJj
On the side, the only engravings are "PAT APR 17 06, OTHER PAT PEND.". I guess these are patent-related details.
Any idea is appreciated!
As for expanding the hole, I am still confident this post will answer your question.
Regarding the Schlage deadbolts, these are not great deadbolts. If you really want high security, you need to look at Mult-T-Lock or Medeco. These are far more secure for a number of reasons. First, they are made of much harder metals - if you feel them compared to another deadbolt there is a noticable weight difference. These deadbolts also often have balls at the end that push out of the bolt when fully expanded so it cannot be forced back in. Also, the keys for these locks can only be made (not copied) by the locksmith who originally created them (each locksmith is assigned a "keyway" and is the only locksmith who can produce the keys), this is handy if you have a cleaning lady or other service person since you can rest assure they cannot make a copy of the key for their friends. There are also metal rings you can put around a deadbolt that spin so that someone cannot use a wrench to twist if off.
If your doors hinges are on the outside then you can also look at having bolts installed on the inside of the door. This way, if the hinges are removed (pins popped out, or blown off with a shotgun), you cannot just pull the door off.
A heaver guage strike (the metal piece that goes on top of the hole where the deadbolt goes into) with longer screws will add extra strength to the deadbolt and hamper someone knocking down the door.
You can also place a cage in front of the door (which too has a deadbolt) but they are not attractive, and add an extra step to opening your door.
An alarm is useful but in a lot of cases, of someone knows what they want, they can be in and out before anyone responds.
A camera adds an extra layer of "don't mess with me" plus gives you a far better chance of identifying an intruder.
This style lockset is known as a mortise lockset.
Dis-assembly and cleaning won't hurt.
While you've got it apart, print the Baldwin diagram below, and note your dimensional differences. Some will be critical (holes for knob and deadbolt), others may be compensated for by strike plate adjustment or wooden block supports (under a shorter mortise body).
Backset (the distance from the door edge to the center of the knob) is a critical dimension that will determine what replacements are available. Modern backsets are usually 2 3/8", many older mortises are 2 1/8 and 2 (the new one below is 2.5)
This page lists some Baldwin mortises, they cover a range of backsets and door thicknesses. Googling "mortise locksets" will net you many choices.
Best Answer
As I mentioned in my comment above it will be very difficult to identify the maker of your old lockset. However. you shouldn't have to if you're simply going to replace it. It should be relatively easy to find a replacement lockset that will fit this door without too much adjusting of the door. However, you're probably not going to know until you remove the old lockset and search out replacement sets. Take the old lockset with you when looking for a new one. With this type of replacement I think that's a better way to find what will work instead of shopping on-line.
There are always some adjustments that need to be made, particularly to mortise in the lockset stile and the strike plate. The wood looks to be in relatively good shape so you might be able to get away with minor refurbishment such as, if necessary, filling in the old screw holes. I like to use wood splinters or toothpicks and wood glue. That's if you're lucky. You will probably have to relocate the strikeplate which may require some wood repair around the original site of the plate. Good luck.