cold formed hinges?

[medusa]

So I've been asked to make a collar different to my usual kind which is basically a hasp and staple set up. I've been playing with the idea of using hinges for ages but unless they are quite thick then I've got concerns about how robust they would be. Anyway, I checked out the Lewton-Brain hinge book and thought that a cold rolled hinge would do the job. For the record, I'm using silver wire which is 5mm x 1.7mm. I need to make the fitting so it and the collar as a whole is very strong and robust, so I'm avoiding soldering as much as possible.

Now the ones in the book didn't look like they were made from very thick sheet, so as much as I wanted to make a nice parallel roll at the ends and then cut out the knuckles, I couldn't get it right. So in the end I pierced out the tabs and then annealed (which kind of counteracts one of the points of doing cold rolled hinges) and managed to get them roughly into shape (after cutting the slots a bit longer). It worked in principle but didn't look very elegant because I managed to really mangle the metal.

So, if I want to make it a nice tight hinge I need to find a way to get a good parallel roll in the silver which is not so enormous that it makes creating a hinge pin unworkable. Or I need to work out how long a tab needs to be to pierce them out but I can't figure out or find out the maths for it. I think it has to do with aspect ratio but after looking online, I can't find out the formula.

Anyone with any advice on how to tackle this?

[Dennis]

I might be alone Liz, but I can only vaguely understand what you are saying.

Whatever the problem, get your collection of free postcards, and make it as well as possible in card first. You can roll card around the stem of a twist drill or whatever to make a tube.

Once you are there, make it in copper next and you will be more confident with silver.

Oh, to roll metal evenly, you need stepped pliers. with the outer beak protected with plastic tubing. Dennis.

[ps_bond]

Off the top of my head, Bealer has (IIRC) something on forming hinges; when you're looking at the thicker stuff then blacksmithing techniques have more applicability. I shall look.

[medusa]

I might be alone Liz, but I can only vaguely understand what you are saying.

Whatever the problem, get your collection of free postcards, and make it as well as possible in card first. You can roll card around the stem of a twist drill or whatever to make a tube.

Once you are there, make it in copper next and you will be more confident with silver.

Oh, to roll metal evenly, you need stepped pliers. with the outer beak protected with plastic tubing. Dennis.

Postcards are too thin and thick card doesn't bend right. I think if curls are that tight then the metal deforms as well.

I have a pair of looping pliers but they are too big still. Not sure how small they go. I need about 2mm max I think.

Off the top of my head, Bealer has (IIRC) something on forming hinges; when you're looking at the thicker stuff then blacksmithing techniques have more applicability. I shall look.

is this who you mean?

I'm attaching a picture of the first mock up I made, the second one is better. The silver comes from off-cuts. I could conceivably use them for rings but I don't make those and I really find it helpful knowing how it works as I'm making it. copper feels really different to me.

[caroleallen]

I don't know anything about formulae but once you've worked out the length, couldn't you just hammer the tabs around a mandrel with a hide mallet?

[Dennis]

I have a pair of looping pliers but they are too big still. Not sure how small they go. I need about 2mm max I think.

The first step on my smaller pliers is 2.0mm in diameter and if needs must, could be ground a little smaller. As for the 'tabs' it is quite easy to adjust them, with a fine saw, to be a little longer or shorter as you go. Dennis.

[ps_bond]

Just checked; what I'm looking for isn't in Bealer, I'll have a look at some of my others and see if I can spot it. From dim memory, there was a steel block with the profile of the hinge in it (so a tangential slot and a hole); you hammer the steel into the block, causing the metal to curl around, then slide it out sideways. Turn it up the other way, hold the silver in a vice and hammer the block onto it... My immediate thought is that doing this with hot steel, there's no spring and the metal contracts as it cools; do it cold with silver and it will spring back against the former, which might make it tricky to remove.

[medusa]

well I got some of the smaller looping pliers but they are really too weedy for thick wire. I have managed with a few bashes at annealing (hopefully the forming got it work hardened in the end!) and I also thinned the wire down to 1mm on the test piece so I'll see how it holds up. The hinge closure seems to be working alright though it could use some finessing.