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Thursday 2 August 2018

Iron wedding rings

Making some iron (mild steel, actually) wedding rings from a railway spike, with bronze decorations

My friends and neighbours Alan and Ildiko decided to get married recently, after about 15 years of engagement and cohabitation, and having 2 together children (taking their time about this allowed them to develop wedding vows based on hard evidence, rather than imagination). 
The first I knew about the wedding plan was being asked by Ildiko if I’d make their rings. “Could you make them out of wood?”, she asked. I worked hard at thinking of a way to make a mostly wooden ring that would be strong enough to survive married life on a finger, but I couldn’t think of anything (short grain is weak). I thought about some way to make rings of metal that would fit the spirit of the occasion. 
The wedding was a celebration of Ildiko’s and Alan’s life together and little family, but also a celebration of the life of Ildiko’s father Bob, who was old and unwell. Railways and steam locomotives had been a big part of Bob’s life, especially in his retirement, in which he had been a leader in a local group that restored and operated a historic locomotive on local lines. Discussion quickly led to the idea of forging a pair of iron wedding rings from an old railway spike, representing Bob’s life travelling over millions of them in trains. 
Ildiko also wanted 4 marks on the rings to represent the 4 members of their little family. This led me to remember a technique my brother-in-law Burke had shown me 20 years or so ago: indenting steel with punches, files, or whatever you like, then filling the dents with brazing bronze, then filing or grinding the surplus bronze back to original steel surface level, leaving the bronze only in the indents. 
So this is what I did (after trying a few things that didn’t work so well): 
    This is the railway spike I started with
  • I found an old railway spike (also called a dog), to draw out. These old-type spikes are the ones used to attach railway lines to old-style wooden sleepers. I’ve previously tested these spikes to be mild steel (by drawing out, heating, quenching, then hitting, to see if it hardened). I thought mild steel to be best for a task like this, as it would not be prone to going brittle, could be safely worked cold, would be easy to draw down to the small section required, and easy to file in the final stages. Not all railway hardware is mild steel tho, the clips used to hold rail to concrete sleepers are spring steel of some sort.
    Drawn-out spike, with angled cut on the RHS for the scarf joint
  • I cut the head off the spike to make it easy to hold in tongs, then drew out a length to a thin flat bar of 4mm x 2mm - what Ildiko thought a suitable section. 
  • I cut a length of bar for each ring, calculated from the inside diameter of a known ring that fitted, plus 2mm for the steel thickness (because that makes the mid-section diameter of the finished ring), times Pi. The lengths were cut with a scarfed end, for joining, so the length is of course only measured on one side, and the scarfed end makes the piece a bit longer. Ring sizes are in increments of 1/10ths of millimetres, and this method turned out to be surprisingly accurate. 
  • Here's the punch, with the tiny star-shaped end
  • I made a punch to make 5-cornered stars in the rings. This was forged from a short piece of spring steel, drawn down rather like a centre punch on the end, then filed into a tapered 5-cornered end, then hardened and tempered. I needed lots of magnification to do the filing on something so small. To get a suitably sharp-cornered file, I took an old chainsaw depth-gauge file and ground the edge square. While discussing this idea with friends I had several offers of torx drivers which would could be used as a round-cornered 6-pointed star punch, but I was clear a tiny mark on a ring should be 5-cornered, and sharp cornered, to be clear to see. 
  • I punched the 4 stars in the piece of flat bar, hot. 
  • These are the tools I used to roll the rings: 1" swage (with concave top), large punch (to fuller the ring into the swage), little hardy horn for adjusting the ring, and hammer
  • I rolled the pieces into rings using a round punch on its side, and a swage (about 1”). This was much easier than I imagined, I reckon it would have been very difficult without the swage. 
    If you look carefully on the far side of the rings, you can just see the diagonal bronze line of the scarf joins
  • The circular rings were brazed in the charcoal forge to fill the stars, and join the ring scarf. I fluxed the brazing sites with some commercial brazing flux, mixed with a few drops of water in a plastic bottle lid and applied with a little brush. The ring was then put stars down in the forge and gently heated to red brazing heat, then turned around so I could see the stars and phosphor bronze applied by touching the site with brazing wire, which melted perfectly over the area. Then the ring was arranged scarf down in the fire, and the scarf brazed, bronze wire applied to the inside of the ring. 
  • The rings were then filed with the flat chainsaw depth gauge file on the outside, and a 5.5mm round chainsaw file on the inside. Filing was mainly flat to file back the bronze level with the original flat bar and show the stars and scarf, then chamfering to remove the sharp edge. I did file the outside surface enough to make the rings a little thinner and less obtrusive on the finger. 
  • Blackening the rings hot, with linseed oil, makes the stars shine out
  • After filing, the stars were very hard to see, with bright bronze against bright steel. This was remedied very easily with normal blacksmith’s blackening: the rings were heated over the forge to a blue heat, then rubbed with a roll of rag with a little linseed oil. At the right temperature the oil smokes and blackens the steel, but doesn’t all burn off. This made the stars come out beautifully. 
  • I made some mistake calculating the size of Alan’s ring, so it was too big. This was easily remedied (after the wedding) by hacksawing thru the scarf joint, then filing and testing the ring on Alan’s finger until it fit. To re-braze the scarf join, I used an oxy torch, for fear of damaging the stars in the forge. 
Everyone is happy with their iron star rings so far. I don’t know how the finish will develop over time, I expect the black to rub off and the steel to become polished in use, so I don’t know how clear the stars will remain - they can be re-blackened for special occasions! Ildiko’s finger had a feint mark of rust red under the ring last time I looked, which doesn’t bother her currently. 
I’m not a jewellery-making sort of bloke, but I loved making these rings. They are themselves crude and humble, but they represent great things: Alan and Ildiko’s relationship, little family and extended family, our friendship, the humble spirit of doing what you need with what you have. 

2 comments:

  1. Really nice work Bruce. They looked great!

    ReplyDelete
  2. I'm a bit speechless. Those are amazing and beautiful.

    ReplyDelete