I forgot to photograph needle files, sometimes useful, see text.
Sharpie, or any marker pen used as a great engineers blue substitute. See text
One of the hardest things for me to get right was making a great butt joint. I kick myself now as it is something I should have seen sooner, being as my hobby before silversmithing and jewellery is model engineering. I also worked in fabrication, as well as various motorcycle projects over the years. My excuse is that I have a tendency to be too ridged in my approaches to things and wanted to be more ‘flowing’ if you will regarding my approach to silversmithing and jewellery. I deliberately tried to forget my formal engineering approaches to help me be more spontaneous. This is another lesson in the interconnectedness of things. This is far too heavy and irrelevant a topic for here for sure.
The textbooks are absolutely right here when they state solder will not hold well if gaps are present. If you look at the kind of strain and abuse I inflict on a join whilst forming with repousse´ it is clear that nearly right is nowhere near good enough. I hope to be able to explain how to create a join so strong that, well look at my cuffs and other work not yet shown here for proof. I dearly like empirical, rather than theoretical evidence, I hope to be able to demonstrate it here so you can attain the results you strive for.
Rings and cuff bracelets present different challanges, I will start with bar stock. By bar stock I mean round, square, oval or whatever, just solid bars of any thickness.
In the first photograph you see all the tools I use, except the needle files, I forgot to put them in the picture, for those who don’t know what they are, just very small files enabling more accurate specific spot removal of material that the bigger files cannot.
The easiest and probably most effective method is to use a chennier cutter. The bar is held firmly and the jewellers saw is accurately placed in a slot preventing the blade from twisting, therefore making a perfect cut with minimal finishing. These tools can be very expensive however, for a beginner or someone who just wants to do occasional work as a hobby they may not want to, or be able to afford such a tool. There is another way for no cost 🙂
An engineers square should be, in my humble opinion, an indispensable part if any toolkit. They come in various sizes and are very reasonably priced. Your bench pin will have a straight edge, with a pencil, I personally prefer to use a sharp scribe as it tears the wood fibres, creating a trench for the next part. If not, make sure your jewellers saw has a tight blade and follow the scribed line, creating a 90 degree little saw mark relative to the edge.
Using a square of triangular file you now carefully file a trench for your bar to rest in. I think the photographs explain better, as you can imagine it was not easy to hold and photograph at the same time. Providing you keep downwards pressure on your bar, wedging it into the groove, presenting it to the file slowly and making sure it cannot jump about. The act of keeping the file pressed against the true bench pin will ensure your two ends will be perfectly flat and true as the 90 degree angle ensures that, as long as you take your time and prevent rocking the file or wire. The human element has been taken out of the equation, the grove and edge being perfect ensures you don’t have to be, it will do it for you.
Sheet presents another challenge, you may be successful with narrow stock, however some of my cuff bracelets are 40mm or more wide. At this width it becomes difficult to coordinate, the filing as the sheet is difficult to locate accurately in the groove.
The trusty engineers square comes to the rescue again, more in a bit. Sharpie felt pens, or any, I use permanent markers, will make great marking guides. In engineering surfaces are checked for flatness with special plates and a beastly substance called engineers blue. Get it by all means is sticks like the preverbal sh12 to a blanket. On skin it will take an age to remove. I thought that marker pens would make a great substitute, they do.
When you cut out your edge, no matter how good you are, the edge will not be entirely flat. To start, file it so it looks flat to you, stop and apply the marker pen to the filed edge. Using a flat plate, like your steel bench block, put some abrasive paper on it stretched tight. I use a piece of abrasive stuck to a piece of board, manmade boards like high grade plywood or MDF are made to tolerances that are useful.
Now GENTLY stroke the piece along the paper making sure you present it to the paper as square on as you can. Now look at the edge, in the photograph I just picked a scrap piece of copper to give an example. Where the black marker has been removed leaving a shining mark, these are high spots, the black areas are low. Now use your file, whatever size is best for the task, gently file the shining bits, coat with the marker and go through the process again and again until you manage to get all the black removed with a single stroke on the flat abrasive paper. Once all of the surface is shinny, the edge is flat.
Not great practice, though I do use it in a hurry or if a particularly wide sheet is becoming difficult, I use the engineers square. Keeping the straight side against the fat part of the square, pushing it firmly against it, I slide the square along the paper whilst pushing the material against the paper. You know this is a perfect 90 degrees as material is being removed along the edge of the square only. This is not great practice as it, technically, makes the square less true as you scrape it along the paper. I would advise that this is done as a last resort, only after you have trued it up as much as you can the other way first. If you do this then you can minimise the damage to the square by using the finest grade of paper you can for the job.
When presenting the ends of your now perfect edges, bent them past and slowly pull them back so the natural spring of the material keeps the seam closed for you, making the wiring of the join not as necessary. I have never wired any of mine, you may still wish to do so. By shining a strong light behind, no light should be visible along the seam. If you see light then a piece of fine abrasive paper can be encouraged into the gap and gently pulled through both sides, using the pressure of the spring in the material, don’t squeeze.
If you follow these steps you will have a joint that is incredibly strong. I always use hard solder as it will return the best results, both strength and colour match. The other beauty of this is that the solder seam is truly wafer thin making invisible seams more attainable. Also for rings you can be confident that the joint will hold up to really quite extreme re sizing as the joint is pretty much guaranteed not to fail, the surrounding material making like a noodle as it shrinks from the join.
I hope this helps, let me know if you need further explanation, or if you know a better/different approach.
Until next time, all my very best wishes.