Yes, I known, I known. I’ve got to many projects going on at the same time, but I was able to borrow this original lock. It’s a flint lock from a 1772 Kongsberg military pistol, gauge 16. It was destroyed in a fire. It’s a bit warped, but useable as a pattern. I’m going to try to make a pair of locks for a brace of pistols.
I made a tracing of the lock plate on thin cardstock and marked all the holes. The hole for the tumbler is 9mm. All the screws were non-standard size, so I chose the closest metric size. The frizzen spring screw is M3, all the rest M4.
I glued the pattern to 1/6” brass sheet, drill all the holes (drill tap size) cut it out. This brass pattern was then glued with locktite superglue to a piece of 7mm thick steel. The blank is then painted blue dykem and pattern scribed around. The glue keeps the pattern from slipping.
All the holes are then drilled with the appropriate drills. The blank is then heated to 170 Celsius, and the brass pattern falls off. Next all the screw holes are taped. It is easier to drill and tap before lock plate is cut out and shaped. Removing the brass pattern before taping avoids enlarging the holes.
Drill 2mm holes all around the plate, outside the outline. One plate takes 154 holes, 2 drill bits and 4 hours.
Saw out the blank and clean up the outline with a file. Remember to keep it square or you’ll change the shape of the lock plate.
Soft solder a chunk of steel to the backside of the plate to clamp it in the vice.
The 1772 lock is a round faced lock. Make a brass pattern for the flat area around the tumbler hole. Use the tumbler hole to line up the pattern, glue, paint with dykem, scribe, heat etc. Remember to scribe line around the plate, 2mm above the lower edge. The face of the lock is rounded down to this line. Start filing at the tail end. Try to stay 1/6” outside the outline. Use a coarse half round file.
Use a pillar file to clean up the outline, then start on the other side with the course half round file.
The vertical line at the nose end marks roughly where the flat part of the plate starts. The horizontal line, the middle of the plate.
Now file away what is left under the tumbler flat. This the most tedious part of the shaping.
The flat area around the frizzen screw is 6mm in diameter. Make a screw with a 6mm head to scribe around. Use a round 5mm chainsaw file to shape this area. Mark and file a simple flat bevel around the rest of the nose of the lock.
It took me 6 hours to shape the rough blank to the finished lock plate. The total from sheet steel about 11 hours, not counting pattern making.
The brass patterns are reusable and makes it simple to make reasonable indentical parts.
Hope to finish the cocks this weekend.
Best regards
Rolf
