This lock project was inspired by the beautiful Alex Henry rifle, built by Curtis.
https://americanlongrifles.org/forum/index.php?topic=55149.0Bob Roller was kind enough to send the pattern and measurements for this Alex Henry/Stanton/four screw type percussion lock. Being a south stanch south paw, I made a left-handed mirror version.
Lock plateThe plate was made from 10 mm mild steel, which was milled down to 7.5 mm before the pattern was glued on with super glue. Paint the blank with dykem, Drill out the holes for the tumbler, screws and pin for the sear. The screws are for 4-40, the sear pin 2,5mm and the tumbler hole 6,5mm. Heat to 200 Celsius and remove the pattern.
Tap the screw holes and drill out the blank with a 2mm drill
Mill out the bolster before sawing out the outline. It’s easier to mount a square blank in the vice.
File clean outline and surface.
HammerAs far as I know, there are no cast left-handed Alex Henry hammers available. You want one, you must make it from scratch. I’d like to thank Curtis for his help with making the pattern. Curtis sent me pictures with measurements from his hammer.
I traced the picture in Qcad, scale 1 to 1. I Then used the measurements to correct the tracing for flaws due to distortions in the photo. The pattern was printed out, mailed to Curtis, compared it to his hammer and suggested corrections. This was repeated until the pattern was acceptable.
When viewed from the side the hammer is composed of three layers stacked on top of each other. Establishing these layers in the blank had to be done before shaping as was the most tedious part of the build.
A. The head, 10,5 mm thick
B. The Body 4mm thick
C. The cone with the axel hole, 3mm
The blank started as a chunk of 20mm mild steel and weighed 700gr. The finished hammer weighs 75gr.
The brass pattern is glued to the blank with super glue and painted with dykem and scribed around.
Notice all the extra material on the right side, this will be needed later when the milling the hammer cup.
Drill out the index holes These allow re-establishing the patten later during some of the milling steps. They also establish some of the tight curves.
Heat, remove the brass pattern and drill out the body with a 2mm drill. Start the holes with a 2mm center drill. This helps tight hole placement and keeps the drill from wandering. On my first attempt without the center, I broke five drills on one blank. With the center drill, I did five blanks one drill and had a lot less filing to refine the outline. Notice the head is not drilled out at this stage. The cylinder next to the center drill is a “feeler” I made to locate the 2mm holes. The center drill point cast a shadow that made it hard place the holes tightly.
Mount the roundtable on the mill. Use two lathe centers to line up the center of the table and the mill.
Mount the drill chuck in the mill. Use the 2mm center drill to locate the tumbler hole in the center of the table and clamp the blank. Drill out to 5,2mm.
Turn two patterns for the cone in the lathe. The big one is 16mm and for the base of the cone. The small one is 10mm and for the top of the cone.
Lock the Y-axis of the mill table (not round table). Mount the big one in the blank, adjust the x-axis and mill out the base of the cone to 3,5mm.
Mount the small pattern and use a 6mm round nose mill to finish the cone.
Remove the round table and mount the mill vice. Mill away the waste to the bottom level of the hammer body.
Turn the blank over and mill away the waste down to the top level of the body.
Saw out the body with a jewelers saw. This is to make sure you don’t nick the hammer head in the next step.
Mount the blank in the vice. Tilt the mill 42,5o and mill out the neck a 6mm mill. There is not room for anything larger.
Mount the head pattern and scribe only the shoulder line.
Mill down to the bottom level of the shoulder.
Use a pillar file to refine the shoulder. Scribe and drill out the head pattern. Finish shaping the body. It’s easier to do before sawing out the head.
Draw a line parallel with end of the cup on the rigth hand side of the blank.
Mill away this corner.
Mount in vice, mill out the cup blank. Drill out an undersized starting hole for the cup in the middle of the blank.
Mount and center the round table on the mill like before. Soft solder the blank to a piece of 1/8” flat stock. Clamp the blank on the round table with the cup hole centered. Lock the y-axis. Off set the x-axis. Mill out the outside of the cup.
Repeat for the inside of the cup. This evens out the wall thickness and creates a flat bottom in the cup.
Saw out the head.
Soft solder onto a steel bar, so you can hold it in a vice while shaping the head with a file. Birds tongue file are good for this.
Finished hammer compared to the original paper patterns.
The last step is to broach the square hole. You’ll find that description here:
https://americanlongrifles.org/forum/index.php?topic=72232.0 
There was a bit trial an error before I got the process rigth. Here’s a picture of the scraped attempts.
Most of the failures were due setup errors with the round table when milling the either the cone around the axel hole or the percussion cup. When setting up the roundtable, three things must line up perfectly before shifting the x-axis on the mill table.
The center of the round table, the center of the mill tool and the center of the circle to be milled.The problem was caused by the work piece shifting on the round table when tightening clamps holding the work piece. Alternating between the clamps, only tightening ¼ turn a time, keeping the pressure equal solved this.
At the moment I'm working on the bridle and screws. Will post it when done.
Best regards
Rolf
