Leg Iron Construction

I recently picked up a pair of older British Darby leg irons. These are the ones with the longer chain, a swivel on each side and a ring in the middle of the chain. I suspected that it was in bad condition and when they arrived my suspicion was confirmed. These were pitted and rust covered to the point you could barely make out the hinges. One of the lock holes appeared to be obstructed.

I had intended to use them as a non-operating display (unless I was wrong about the condition) so I decided to open the lock cases. I am not a lock smith or a handcuff mechanic but generally tearing things apart doesnt require any special skill. I have heard several experienced darby repairmen say that you can knock the lock plug out by hitting the lock bolt from the other end. It workedsort of. The lock case was in such bad condition that it split behind the opening for the bow. The plug didnt move.

The insides were interesting. John Bushey has a pair of these and described the springs as super strong. On one side the spring was long and still packed a good deal of tension. The other side had a much shorter spring. It appears that the upper spring block which also acts as a bolt guide did not go as high in one lock body as it did the other. I believe that these pieces were hand filed and then tapped into the lock case. Then a piece of spring stock was dropped into the lock case and cut to size. The length of the spring would have been determined by where the spring stop ended up in the lock case. In these leg irons the spring on one side was probably 30% longer than on the other side.

The obstruction that I saw on one side was in fact a broken key which happened to be on the side with the longer spring. My guess is that as these internal parts were machine made in the later cuffs, the inconsistency of the different sized springs would have diminished.

It was interesting to have a look inside the lock cases but working on a nice pair should be left to the Ian McColls of our hobby.


Damon

Hi Damon, you have taken the first steps in becoming a handcuff mechanic, well done.

Ian

I recently picked up a pair of older British Darby leg irons. These are the ones with the longer chain, a swivel on each side and a ring in the middle of the chain. I suspected that it was in bad condition and when they arrived my suspicion was confirmed. These were pitted and rust covered to the point you could barely make out the hinges. One of the lock holes appeared to be obstructed.

I had intended to use them as a non-operating display (unless I was wrong about the condition) so I decided to open the lock cases. I am not a lock smith or a handcuff mechanic but generally tearing things apart doesnt require any special skill. I have heard several experienced darby repairmen say that you can knock the lock plug out by hitting the lock bolt from the other end. It workedsort of. The lock case was in such bad condition that it split behind the opening for the bow. The plug didnt move.

The insides were interesting. John Bushey has a pair of these and described the springs as super strong. On one side the spring was long and still packed a good deal of tension. The other side had a much shorter spring. It appears that the upper spring block which also acts as a bolt guide did not go as high in one lock body as it did the other. I believe that these pieces were hand filed and then tapped into the lock case. Then a piece of spring stock was dropped into the lock case and cut to size. The length of the spring would have been determined by where the spring stop ended up in the lock case. In these leg irons the spring on one side was probably 30% longer than on the other side.

The obstruction that I saw on one side was in fact a broken key which happened to be on the side with the longer spring. My guess is that as these internal parts were machine made in the later cuffs, the inconsistency of the different sized springs would have diminished.

It was interesting to have a look inside the lock cases but working on a nice pair should be left to the Ian McColls of our hobby.


Damon

Click to expand...

Alot of those old darbies are well made and not all the end plugs can be tapped out that easy. What I would do to tap one out is to take a Dremel with a diamond cut off wheel and make a cut just deep enough in the lock case where the plug is and the bow goes into the lock case. Then the plug can be put back in place and TIG welded in place. Recently I had to remove some sort of broken key in the lock and the way I removed it was to push the bolt as far back as I could. Then between using a small carbide drill bit and a needle file cut down far enough and split open the tube of the broken key and with needle nose pliers and small screwdrivers backed it out.

I recently picked up a pair of older British Darby leg irons. These are the ones with the longer chain, a swivel on each side and a ring in the middle of the chain. I suspected that it was in bad condition and when they arrived my suspicion was confirmed. These were pitted and rust covered to the point you could barely make out the hinges. One of the lock holes appeared to be obstructed.

I had intended to use them as a non-operating display (unless I was wrong about the condition) so I decided to open the lock cases. I am not a lock smith or a handcuff mechanic but generally tearing things apart doesnt require any special skill. I have heard several experienced darby repairmen say that you can knock the lock plug out by hitting the lock bolt from the other end. It workedsort of. The lock case was in such bad condition that it split behind the opening for the bow. The plug didnt move.

The insides were interesting. John Bushey has a pair of these and described the springs as super strong. On one side the spring was long and still packed a good deal of tension. The other side had a much shorter spring. It appears that the upper spring block which also acts as a bolt guide did not go as high in one lock body as it did the other. I believe that these pieces were hand filed and then tapped into the lock case. Then a piece of spring stock was dropped into the lock case and cut to size. The length of the spring would have been determined by where the spring stop ended up in the lock case. In these leg irons the spring on one side was probably 30% longer than on the other side.

The obstruction that I saw on one side was in fact a broken key which happened to be on the side with the longer spring. My guess is that as these internal parts were machine made in the later cuffs, the inconsistency of the different sized springs would have diminished.

It was interesting to have a look inside the lock cases but working on a nice pair should be left to the Ian McColls of our hobby.


Damon

Click to expand...

Here are the springs from the leg ions. John Bushey wasn't kidding when he said they were super strong. The are like engine valve springs! Easy to see how a key might get broken.

Damon