Thursday, September 20, 2007

Making a Bayonet Catch

This Blog assumes you are familiar with goldsmithing techniques and the diciplines there of
Any questions can be sent to
Click on the pictures to enlarge them.

This was a clasp that I designed as I went along, i.e this was the first time I had made such a thing.

I had a customer come into my shop and he wanted to have a stainless steel cable necklace with a rubber tubing on the outside. He is a yacht racer so it had to be strong.
I made him a silver and gold whistle before and he wanted to have something to hang it on.

The cord that is pictured was just temporary.
The catch presented a problem, because I could not use a 'normal store bought' catch and it had to go with the flow of the piece Also the machine made catches have steel springs in them and here in St.Maarten, unless it is stainless steel, it dies fast.
Anyway, the following is what I made.

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

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

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

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

Then to see if it all is aligned and slides easily in and out, before I cut the next slit.

Then I cut the next 'upward slit. 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.

Like about this long

Then I soldered a jump ring in the tube. This will be the stop for the stainless steel spring .
don't worry, 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 jumpring.

Like this--apologies for the kak picture!!!

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 indespensible. It pays well to have them handy.....
Anyway, to continue..

Okay, so now I got a bit stupid and I got hung-up on the smithing part of it and not the smithing and PHOTO as well. So I have, in the picture below solderd 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 neclace, 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 Jonson and Matthey called 'Easy Flo' ( figures, doesn't it, they would hardly call it 'difficult flo', ha ha)

So there is the whole catastrophe about to be all inserted. The cable part will be riveted . You can just see the hole at the bottom. The spring is stailless steel. The previous picture shows the male part. The tip of the male will press against the plug that is infront of the spring. (does that
make sense?)

I gave the customer the necklace to wear for a week, so he can 'road test' it. 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 jumpring around the female part, right at the front. It will make the split tubing much stronger.

There is he and she together in matrimonial bliss!

All that I did after, is rivet the rivet sticking out and polish....

Hope you enjoyed this post and that all is understood.

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