There have been some inquiries about lock polishing and tuning. I will show how I polish and lightly tune a lock that works great out of the box. The goals are to present a lock with polished surfaces inside and out, ready to use, case harden, brown or blue, and to reduce friction.
This show and tell is for newbies. Nothing here to see for experienced builders.
There are many approaches. This one uses few expensive items. It will take me a while to get this done and maybe it will be a tutorial. Please limit replies to questions and critique to save space.
Hippocratic oath of lock polishing and tuning: First, do no harm!This means we will strive to not ruin the fit of parts by over-filing or polishing and will not make any lock less safe.
Lock disassemblyHere is the lock.
Remove the mainspring using a mainspring vise with lock on full cock.
Remove the mainspring vise.
Use the mainspring vise to remove the frizzen spring next.
Remove internals: sear spring, sear, and bridle. Now see the fly.
Remove the fly and know it is an escape artist. I tape it to a piece o& paper and fold it up.
Now we will drive the tumbler off the cock. I lay the plate across open vise jaws with a catch cloth beneath. Then I punch it with a quickly made brass punch.
There we are, all disassembled and parts in a container.
Polish plate and panDo no harm. There is a great fit of pan to plate. You can make it a lot worse by over-filing or polishing. Below in pencil I am showing where we have to be careful to not remove any more than necessary to remove pebbled, as-cast surface.
Lock plates are never perfectly flat and do not need to be. But we are using flat files for first step. A coarse and fine side.
To remove as little as possible, protect where the pan will fit, and get the plate reasonably flat I file the outside of the plate in 3 directions. Angling 10 o’clock to 4 o’clock, 2 o’clock to 8 o’clock, and 9 to 3 to sort of blend. There will always be a dish somewhere to file down to. Also be careful up where the frizzen pivots. Remove as little as possible there to reduce polishing-induced slop.
Showing directions I file.
First I file. Then I polish with successive grits of 150, 220,and 320 paper backed by files. Might as well go to 320 on whatever piece I am polishing and call it done b
Next we will file then polish the edges. I use a #2 half round file and needle files.
On the pan assembly, do not mess with the area that engages the lock plate, or risk a loose fit.
Ok now we have plate and pan polished.
Tomorrow: the dreaded frizzen.