How to Repair Mortise Locks on Metal Frame Doors

A mortise lock is a hardware device used to secure a door. While cylindrical locks are installed through a small hole drilled in the door, mortise locks are placed into a pocket cut into the door. They become a part of the door itself, making the opening much more secure. While it is fairly easy to adjust mortise locks in wood frames, it can be slightly more difficult if the frame is made of metal. This is because installers will require more advanced tools to complete this task.

Things You'll Need

• Screwdriver
• Compressed air
• Metal file
• Grinder
• Silicone spray or wax
• Putty knife

Instructions

Aligning the Lock

1. Open the door and activate the knob or lever. If the latch is retracting normally when the door is open, any problems you are having are likely due to misalignment with the lock strike. To fix this problem, you'll have to re-align the latch so it meets the strike.

2. Tighten the screws in all three hinges. Over time, the weight of a door will pull the hinges loose from the frame slightly. Use your screwdriver to tighten all the screws you see in each hinge. This will often pull the door back into alignment enough for the lock to meet the strike.

3. Check the strike plate. If it is too close to the latch when the door is closed, try tightening the screws that hold it in place. If it is still too close, remove the plate and use a grinder to grind the frame slightly behind the strike plate. Once the plate is reinstalled, it will be further from the mortise lock, allowing the latch to fit properly.

4. Clean the hole in the strike plate. If dirt or debris are collected in this hole, there may not be enough room for the latch. Spray compressed air into the hole, or use a pointed object to loosen and remove any debris.

5. Widen the hole in the strike plate. Use a metal file to widen this hole slightly so that the bolt will fit. This is the best solution when the bolt is too large for the hole, or in instances where the bolt is rubbing along one side of the hole.

Other Repairs

1. Grease the latch bolt with silicone spray or wax. This will allow the latch to retract more easily, and may eliminate simple problems with sticking.

2. Remove paint or dirt from the latch plate. Open the door and examine the edge where the latch protrudes from the door. The latch and surrounding metal plate are often painted over, which can cause the latch to stick. Use a putty knife to scrape away paint that may be blocking the operation of the lock.

3. Take the lock off the door and clean it. Remove the screws holding the latch plates on the edge of the door. From the inside of the home, remove any screws holding the cylinder in place. Take the cylinder out through the front of the door, then remove the lock itself through the edge of the door. Spray compressed air into the lock to blow out dust. Wipe the lock and cylinder clean with a household cleaner to remove dirt and grease. Dry the lock and reinstall to test operation.

4. Re-align the cylinder. If the cylinder is not installed properly, it will be difficult or impossible to use. Remove the screws holding the cylinder in place, then slide it through the front of the door. Insert the key so that the teeth point straight up towards the ceiling. Keeping the key in this position, reinsert the cylinder and screw it in place. Remove the key. The cylinder will now be in the correct position and should operate more effectively.

References

• The Natural Handyman
• The Complete Book of Locks and Locksmithing; Bill Phillips; Mc-Graw Hill; 2005
• Door and Frame Standards; Door and Hardware Institute; 2005