Thursday, March 24, 2011

Mortise Lock Repair

Mortise locks are common in homes from the Colonial, Federal, Victorian and Arts & Crafts periods. Dating from 1607 to the 1920’s (over three hundred years), these locks in various forms were widely used. There are many resources to replace these mechanisms when they fail; however, I have found that finding suitable parts that actually fit is difficult. To be honest, these mechanisms are fairly simple and repair can be done by just about anyone with a modest level of skill.

Removal: Removal of the mortise lock from the door is easy. Simply remove the two screws on the faceplate holding the mechanism in place.

Disassembly: The first step in the process is to find the machine screw that holds the cover plate in position and remove it. I am sure that there may be manufacturers that may have used a different (2, 3 or more screws) configuration, but I have never seen them differ from this:

Once the cover is removed, take note of the position of all the bolts, levers, and springs.

Take special care (and I speak from experience here!) to note the EXACT position of the retainer springs…and there will most likely be two of them. These springs are critical to smooth and proper operation.

This is also a good time to inspect the mechanism for damage and to note what repair actions should be taken. The most common reasons these mechanisms fail:
  • PAINT, PAINT, and did I mention PAINT? More often than not, at some point in history, someone painted over the mortise lock rendering it unusable. A simple cleaning of the parts in paint stripper and mineral spirits usually does the trick.
  • Broken springs. Suitable replacements can usually be found at a hardware store or online dealers abound.
Remove the springs first. In my example, there are three. Once the springs are removed the rest of the parts pretty much fall out so be careful. When you remove, the parts make sure to lay them out so you can remember how they go back.

Once the parts are cleaned, a liberal application of lubricant will help the unit operate smoothly. Do not use a spray (like WD-40) this stuff makes a mess and attracts dust/dirt. The best lubricants to use are Teflon, or graphite type lubricants. In this application, I would also accept the use a lithium based lubricant.

Reassembly is reverse of removal. Just be sure the leaf type retainer springs are placed exactly where they should be.

Test the operation of the cam, bolt, and latches before installing the mortise lock mechanism. You can use the door set and skeleton key to check that everything works.

Alternatively, if this seems a little difficult…Please give Savannah Renovations a call at 912-675-5569 and we will be right out to repair your mortise locks and have them working as good as new!