Making Bayonet Catch - Free Tutorial

I made this silver and gold whistle for a customer who is a yacht racer. He wanted to have a stainless steel cable necklace with a rubber tubing on the outside. 

First, two sizes of tubing. As the picture shows, they slide easily into each other. The wall thickness was about .80 to 1mm. The thicker one was about 6mm. OD and 4mm ID and the thinner one was about 4mm OD and 2mm ID.
Make Tubing - How To teaches more about this in detail. 

First I saw a cut into the tubing and then I used a 1mm barrel frazer to make two grooves down either side. About 8mm down.

Then cut about a 1.5 mm opposite lock, starting to form the 'bayonet hook' of the catch.
All this burring is done with a 1mm barrel frazer.

In the smaller tube, I drill a 1mm hole through and solder a piece of wire into it.

Then check if it all aligns and slides easily in and out. 

Now I cut the next 'upward groove'. This is the locking part, that will be under pressure from the spring, a few photos down.

I saw the tube off at more or less the black line.

About this long.

Then I soldered a jump ring in the tube. This will be the stop for the stainless steel spring .
The next pictures will make it clear.

This is the jump ring soldered in and filed and sanded down
Then, in the thinner tubing on the left, I solder a piece of wire that is the same diameter as the inner diameter of the previously soldered jump ring.

The wire pin is soldered like this. 

So that it fits easily in and out.

So now I solder the piece of tubing back on that I cut off a few pictures ago. I use the soldering tweezers pictured ...not very often, but boy, when you need them, they are indispensable. It pays well to have them handy.....

Okay, so now I got hung-up on the 'smithing part of it and not the smithing and PHOTO as well. So I have, in this picture  soldered the two pieces of tubing together.

So anyway, I made one plug, not two as pictured. One goes in the back of the tubing and then comes up against the jump ring that was soldered in earlier where the black line is.

Since this is a cable/ rubber necklace, the 'bayonet hook' part is soldered onto the cable. This is stainless steel cable and with an aggressive flux, solders quite easily to silver with silvers hard solder. Gold solders also work very well. I use a South African flux made by Johnson and Matthey called 'Easy Flo'.

All these components are about to be all inserted. The cable part will be riveted . You can just see the hole at the bottom. The spring is stainless steel. The previous picture shows the male part. The tip of the male will press against the plug that is in front of the spring. (does that make sense?)

The customer did a 'road test' for a week to see how easy the catch is to operate.   He is one of these dudes who knows exactly what he doesn't want! (grin)
One modification I have thought of, is to solder a jump ring around the female part, right at the front. It will make the split tubing much stronger.

All that I did after, is to rivet the rivet sticking out and sand it all smooth and polish.