Finished the tumbler, bridal, sear and sear spring. I’m not sure how long this took, due to sloppy time keeping and the fact I had to redo the parts several times before I got them right. A rough estimate would be around 30-40 hours for each lock.
Each tumbler blank starts as a piece of 30mm round stock, about 50mm long. Remove the scale with a dull file before hacksawing off the piece, otherwise your going to use up a pile of blades.
On my first two attempts, I turned the small axel first, then reversed the blank to turn the main axel. This did not work well for two reasons.
1. If you take the blank out, you will never get it back in, in exactly the same position. Due to this wobble the two faces of the tumbler won’t be parallel.
2. Mounting the small axel in the chuck with the face against the front of the jaws, gets rid of most of the wobble. But the small axel is prone to breaking when turning the main axel.
True up the blank face and clean up the side. Now turn down the main axel to 9mm diameter. Leave a 12mm ring at the base of the axel about 0,1mm (1/128”) high, to reduce friction against the lock plate.
Center drill, drill and thread the main axel before removing the blank from the chuck. This keeps everything true, square and centered.
Reverse the blank, mount by the main axel with the tumbler face against the tip of the chuck jaws. Turn down the small axel to 4mm. Remember to leave a small ring at the base.
Take the tumbler blank and cut off a piece at the top to make room for the lock plate bolster. Measure the thickness of the lock plate and add 0,7mm (1/64”). Mill out a square piece of steel this thickness. Drill a hole in the middle, the size of the main axel. Superglue the blank to the square with the main axel through the hole. Make sure the flat top of the tumbler blank is square to diagonal of the square piece of steel. This will make locating the square hole in the cock easier. Will explain when we get to that.
File the main axel square. Use a pillar file and keep the file lined up with one of the squares sides. Check with a machinist square. The steel square will insure that the cock will 1/64” above and parallel with the lock plate. One of the diagonals that run through the corners of the square axel will bisect the flat top on the tumbler. This line is parallel with the axes through the cock in the half notch position.
When marking out the corners of the square hole in the cock, keep flat on the tumbler blank parallel with the lower jaw of the cock. This squares up the vertical line through the cock with the horizontal line through the lock plate. The cock and tumbler are now in the position you want when the sear should engage the half cock notch. Does not matter if you are a bit off as this can be adjusted when cutting down the rest of the tumbler. Mount the tumbler and cock on the lock plate.
Cut down the shoulder of the cock until it rests on the lock plate in the fired position. Use Preussen blue on the lock plate. Dismantle, file away the blue on the shoulder. Repeat until full contact.
Time to start on the bridal. We will get back to the tumbler later. Find a piece of steel where the thickness = tumbler thickness + 2mm. Super glue the lock plate pattern to it. Drill the holes for the sear screw and bridle screw, cut off the blank and mill out the bridle post
Turn a brass drill guide. The center hole =small axel. The cylinder = large axel. Mount the blank on the blank on the lock plate.
Drill the hole for the small axel. Draw the shape of the bridle around the holes and saw out.
Cut down the rear of the tumbler disc until it hits the rear of the bridle bolster, when the cock shoulder hits the lock plate. Draw a line parallel with the bottom of the lock plate, distance 5mm. Cut the nose of the tumbler here.
Saw out the rest of the tumbler, leave enough material for the sear notches.
Mount the tumbler and the cock on the lock plate. Place the cock in the half cock postion and mark the half cock notch on the tumbler. Do the same for the full cock position. File the notches and make a pattern for the sear in brass sheet metal. Cut the sear out of a piece of angel iron. (sorry, forgot to take pictures).
Next part was the sear spring. This part drove me slowly nuts. Think I made every conceivable mistake possible, before I got it right. Once figured out, its was really quite simple. I used Brownell spring stock 1/8” thick. Start with a piece 10mmx 55mm. Cut in 3,5mm from each edge. Heat, twist and anneal.
Straighten the tab so is square to the rest of the blank.
Reduce the thickness of the spring to 2mm by taking 0,5mm off from each side. Mill out the tab. Leave it big enough to allow final adjustments.
Drill the sear screw hole. Make the sear screw and matching round nut. File out the sear spring eye.
Mount the blank on the lock plate. Mark out the slot for the spring tab and drill it out with a 2mm drill. Careful with the depth so you don’t drill through the lock plate. Break webs between the holes with a graver (Forgot to take pictures). Glue the blank with super glue to a piece of scrap and file a taper.
Polish the blank, bend, harden and temper (forgot pictures, sorry).
The next chapter will be the main spring and the frizzenspring.
Here are links to the parts done sofar:
Part one, the lockplate.
http://americanlongrifles.org/forum/index.php?topic=49769.0Part two, the cock.
http://americanlongrifles.org/forum/index.php?topic=49838.0Part three, the pan.
http://americanlongrifles.org/forum/index.php?topic=50191.0Part four, the frizzen.
http://americanlongrifles.org/forum/index.php?topic=51056.msg506885#msg506885Best regards
Rolf
