This is how I suggest dissembling and reassembling a side lock.
There may be some things I've overlooked so for a while, I'll leave this topic open for comments. Once I decide the corrections were good and I update this post, I'll remove the comments and make the topic a sticky.
TAKING A LOCK APART
1. Take a good look at the way the mainspring powers the tumbler. If it is just pushing against a spur on the tumbler, go to step 2. If the mainspring is connected to the tumbler with a link, get your camera and take several pictures of it before taking anything apart. That link will only work correctly with it installed one way and it is easy to put it together backwards. The link usually has an "S" bend shape so make sure you can see the way it is installed. If you don't have a camera, make a sketch of how it is installed on a piece of paper.
2. Bring the hammer/cock to the full cocked position. Install the spring vise on the compressed mainspring snugging it up. Don't attempt to compress the mainspring further by over-tightening it. Overtightening the mainspring can cause it to break.
With the vise installed, push up on the sear arm to release the tumbler. Rotate the hammer/cock forward and remove the mainspring from the plate. There is a protrusion on the mainspring that is a slip fit into a hole in the lockplate. Slightly rotating the mainspring with the vise attached will allow the spring to be removed from the lock plate.
Sit the compressed mainspring and mainspring vise aside.
3. If the lock is a flintlock, remove the frizzen feather spring. The spring can be compressed with a pair of locking pliers with a piece of heavy cloth on the jaws to protect the spring. It doesn't take much force to do this and remember, you want to compress that spring ONLY ENOUGH to get it free from the lock plate. DO NOT over compress that feather spring or it will break.
Also, remove the screw that holds the hammer/cock onto the tumbler.
4. Remove the sear spring at the rear of the lock. It has a tab in the upper arm that holds it in addition to the screw. Just push it downward slightly and away from the plate and it will come off. Also remove the sear screw and the sear at this time after the spring is removed.
5. Remove the bridle that covers the tumbler. This will often expose the fly that is in the tumbler so make sure it doesn't fall off. Once found, remove the fly and stick it onto a piece of masking tape so it doesn't get lost.
6. You now need two supports to hold the lock plate on a table when it is face up with the inside of the lock facing down. The supports must be tall enough so that the tumbler will clear the table by at least 3/8 of an inch.
Place a support on one side of the tumbler and the other support on the other side of the tumbler with the tumbler hanging loosely down between them.
7. Now, you will need something to drive the square tumbler drive out of the hammer/cock. If you have a short piece of steel or brass rod with the ends square with the rod, get it. It should be slightly smaller than the square drive of the tumbler. A 1/4" drive socket wrench extension will sometimes work for this. ( I've also been known to get a large carpenter nail that will just fit down thru the threads that the hammer/cock screw was screwed into and I filed the point off leaving a flat surface on it.) I'll call this a "driver".
8. Place the "driver" against the end of the tumblers square drive (or the nail into the screw hole) and using a very small mallet or hammer, lightly tap the driver down, forcing the tumbler drive out of the hammer/cock. (The hammer/cock will be supported by the upper surface of the lock plate while your doing this).
9. It shouldn't take much force to drive the square drive out of the hammer/cock so start by just tapping. If it needs more force then increase the force of the blows a little.
10. If the lock is a flintlock there will be a screw that holds the frizzen in place. Removing the screw will allow the frizzen to be removed.
REASSEMBLING THE LOCK
1. Place the tumbler into the lock plate. While your looking at it, rotate the tumbler counterclockwise until the tumbler stops on the lockplate bolster. If it doesn't stop, rotate it until the spur that the mainspring will push on or the fork the mainspring link attaches to is pointing toward the front of the lock.
You will want the tumbler to be in the same position as it normally operates in when the lock is in the un-cocked position.
Rotate the lock so the outside of the lockplate is up and the tumbler is resting on a good support. A small socket from a socket wrench set will work nicely. If you don't have one remember, the small axle on the tumbler will poke a hole in whatever it is resting against when you install the hammer/cock.
Now, study the hammer/cock and determine which of the 4 positions it should be when it is in the "fired" position and start it onto the tumbler square drive.
2. Several light taps of a mallet should be enough to drive the hammer onto the tumblers square. Try to keep the underside of the hammer/cock parallel with the top surface of the lock plate while your doing this.
When you figure the hammer is all the way on, get a good flashlight and shine it into the gap between the hammer/cock and the lockplate. Look down into the gap and determine if the hammer/cock has been driven on so that its rear face is snugly seated against the 4 shoulders where the square drive ends. If it is, move on to the next step. If the hammer/cock is not against the ends of the flats, tap it on further.
3. Install the fly back onto the tumbler. If this is a Siler style lock the fly has a pin on it and it can only be installed one way. If the lock is one of several L&R locks, the fly is a thin piece of metal with a hole thru it. It can be installed two ways but only one of them will work correctly. Make your best guess when you install it but keep in mind, if the fly doesn't block off the half cock slot when the hammer is falling from the full cock position, the fly was installed backwards.
4. Replace the bridle and the sear. Note: The bridle screws can be fully tightened. The sear screw should only be slightly snug. The sear should rotate easily when its screw is tightened correctly.
If the lock is the L&R type, now is the time to test the fly. To do this, apply a downward pressure to the sear arm and pull the hammer/cock back to the full cock position. The nose of the sear should fully engage the full cock notch. Now, push up on the sear arm and slightly rotate the hammer/cock forward. After the full cock notch rotates above the nose of the sear, push downward on the sear arm with a moderate to hard pressure and continue to rotate the hammer/cock forward. If the fly was installed correctly the nose of the sear will hit it pushing it forward so that it blocks off the half cock notch.
Further movement of the hammer/cock should make the nose of the sear jump over the fly and the hammer/cock will continue to fall. If the sear refuses to jump over the fly, the fly was installed backwards so remove the bridle and turn the fly over.
Make sure the sear and fly are working correctly before you go on.
5. Install the sear spring. To do this, screw the screw thru the spring hole. The rear of the sear spring will be sticking upward. Use your thumb to push this end of the spring downward and continue pushing it down until the tab on the spring slips into the slot in the lock plate. Then, tighten the sear spring screw.
6. With the hammer/cock resting in the fired position, insert the mainspring (with the vise still holding it compressed) back onto the lock plate.
If the lock uses a link between the mainspring and the tumbler fork, install the link now.
Move the hammer/cock to the full cock position and remove the mainspring vise.
7. If the lock is a flintlock, replace the frizzen and the frizzen spring and if I didn'tmiss something, your done.
There may be some things I've overlooked so for a while, I'll leave this topic open for comments. Once I decide the corrections were good and I update this post, I'll remove the comments and make the topic a sticky.
TAKING A LOCK APART
1. Take a good look at the way the mainspring powers the tumbler. If it is just pushing against a spur on the tumbler, go to step 2. If the mainspring is connected to the tumbler with a link, get your camera and take several pictures of it before taking anything apart. That link will only work correctly with it installed one way and it is easy to put it together backwards. The link usually has an "S" bend shape so make sure you can see the way it is installed. If you don't have a camera, make a sketch of how it is installed on a piece of paper.
2. Bring the hammer/cock to the full cocked position. Install the spring vise on the compressed mainspring snugging it up. Don't attempt to compress the mainspring further by over-tightening it. Overtightening the mainspring can cause it to break.
With the vise installed, push up on the sear arm to release the tumbler. Rotate the hammer/cock forward and remove the mainspring from the plate. There is a protrusion on the mainspring that is a slip fit into a hole in the lockplate. Slightly rotating the mainspring with the vise attached will allow the spring to be removed from the lock plate.
Sit the compressed mainspring and mainspring vise aside.
3. If the lock is a flintlock, remove the frizzen feather spring. The spring can be compressed with a pair of locking pliers with a piece of heavy cloth on the jaws to protect the spring. It doesn't take much force to do this and remember, you want to compress that spring ONLY ENOUGH to get it free from the lock plate. DO NOT over compress that feather spring or it will break.
Also, remove the screw that holds the hammer/cock onto the tumbler.
4. Remove the sear spring at the rear of the lock. It has a tab in the upper arm that holds it in addition to the screw. Just push it downward slightly and away from the plate and it will come off. Also remove the sear screw and the sear at this time after the spring is removed.
5. Remove the bridle that covers the tumbler. This will often expose the fly that is in the tumbler so make sure it doesn't fall off. Once found, remove the fly and stick it onto a piece of masking tape so it doesn't get lost.
6. You now need two supports to hold the lock plate on a table when it is face up with the inside of the lock facing down. The supports must be tall enough so that the tumbler will clear the table by at least 3/8 of an inch.
Place a support on one side of the tumbler and the other support on the other side of the tumbler with the tumbler hanging loosely down between them.
7. Now, you will need something to drive the square tumbler drive out of the hammer/cock. If you have a short piece of steel or brass rod with the ends square with the rod, get it. It should be slightly smaller than the square drive of the tumbler. A 1/4" drive socket wrench extension will sometimes work for this. ( I've also been known to get a large carpenter nail that will just fit down thru the threads that the hammer/cock screw was screwed into and I filed the point off leaving a flat surface on it.) I'll call this a "driver".
8. Place the "driver" against the end of the tumblers square drive (or the nail into the screw hole) and using a very small mallet or hammer, lightly tap the driver down, forcing the tumbler drive out of the hammer/cock. (The hammer/cock will be supported by the upper surface of the lock plate while your doing this).
9. It shouldn't take much force to drive the square drive out of the hammer/cock so start by just tapping. If it needs more force then increase the force of the blows a little.
10. If the lock is a flintlock there will be a screw that holds the frizzen in place. Removing the screw will allow the frizzen to be removed.
REASSEMBLING THE LOCK
1. Place the tumbler into the lock plate. While your looking at it, rotate the tumbler counterclockwise until the tumbler stops on the lockplate bolster. If it doesn't stop, rotate it until the spur that the mainspring will push on or the fork the mainspring link attaches to is pointing toward the front of the lock.
You will want the tumbler to be in the same position as it normally operates in when the lock is in the un-cocked position.
Rotate the lock so the outside of the lockplate is up and the tumbler is resting on a good support. A small socket from a socket wrench set will work nicely. If you don't have one remember, the small axle on the tumbler will poke a hole in whatever it is resting against when you install the hammer/cock.
Now, study the hammer/cock and determine which of the 4 positions it should be when it is in the "fired" position and start it onto the tumbler square drive.
2. Several light taps of a mallet should be enough to drive the hammer onto the tumblers square. Try to keep the underside of the hammer/cock parallel with the top surface of the lock plate while your doing this.
When you figure the hammer is all the way on, get a good flashlight and shine it into the gap between the hammer/cock and the lockplate. Look down into the gap and determine if the hammer/cock has been driven on so that its rear face is snugly seated against the 4 shoulders where the square drive ends. If it is, move on to the next step. If the hammer/cock is not against the ends of the flats, tap it on further.
3. Install the fly back onto the tumbler. If this is a Siler style lock the fly has a pin on it and it can only be installed one way. If the lock is one of several L&R locks, the fly is a thin piece of metal with a hole thru it. It can be installed two ways but only one of them will work correctly. Make your best guess when you install it but keep in mind, if the fly doesn't block off the half cock slot when the hammer is falling from the full cock position, the fly was installed backwards.
4. Replace the bridle and the sear. Note: The bridle screws can be fully tightened. The sear screw should only be slightly snug. The sear should rotate easily when its screw is tightened correctly.
If the lock is the L&R type, now is the time to test the fly. To do this, apply a downward pressure to the sear arm and pull the hammer/cock back to the full cock position. The nose of the sear should fully engage the full cock notch. Now, push up on the sear arm and slightly rotate the hammer/cock forward. After the full cock notch rotates above the nose of the sear, push downward on the sear arm with a moderate to hard pressure and continue to rotate the hammer/cock forward. If the fly was installed correctly the nose of the sear will hit it pushing it forward so that it blocks off the half cock notch.
Further movement of the hammer/cock should make the nose of the sear jump over the fly and the hammer/cock will continue to fall. If the sear refuses to jump over the fly, the fly was installed backwards so remove the bridle and turn the fly over.
Make sure the sear and fly are working correctly before you go on.
5. Install the sear spring. To do this, screw the screw thru the spring hole. The rear of the sear spring will be sticking upward. Use your thumb to push this end of the spring downward and continue pushing it down until the tab on the spring slips into the slot in the lock plate. Then, tighten the sear spring screw.
6. With the hammer/cock resting in the fired position, insert the mainspring (with the vise still holding it compressed) back onto the lock plate.
If the lock uses a link between the mainspring and the tumbler fork, install the link now.
Move the hammer/cock to the full cock position and remove the mainspring vise.
7. If the lock is a flintlock, replace the frizzen and the frizzen spring and if I didn'tmiss something, your done.
