This was a practice with silver work: how to create a hollow cube? Hollow as silver as a material is of course bit expensive but also as solid cube would be really heavy. Heavy is not something one wants for example with jewellery.
First saw rectangle billet that has at least 0,5mm extra on each side. One needs some extra material, so that the part can be filed into exactly to the needed dimensions.
Mark lines with vernier caliper to where we want to create folds ( one to the centre and so on ). Notice that material stretches when it is bent, so if one makes the dimensions all the same, one will not end up with square form after bending the piece!
Use then saw to create grooves to these lines.
Deepen the grooves with square file. Grooves must be bit deeper than half of the plate thickness. One can also file the ends bit closer to needed length and give them 45 deg angle.
After this anneal the piece. Annealing means heating the metal so that it becomes softer and therefore easier to work with. This also prevents the metal from snapping so easily.
Temperature in annealing is high enough when the piece becomes orange-red.
( Sorry, bad picture but was taken in action... Shows the wanted colour still. )
After piece has cooled down, its colour has changed into almost black because of oxidising.
Oxidised layer must be filed out from grooves and ends because otherwise those parts will not solder.
Then bend the piece into wanted shape with pliers. Check that angles are set square and that outside dimensions are as they should be.
Solder all angles.
This means putting few layers of soldering liquid to the surfaces and heating the liquid before adding another layer.
Remember to add soldering liquid to the soldering wire also. It is easiest to heat the soldering wire a bit, so it contracts into ball shape because then it will most likely run into the wanted junction.
Balls of solder ready to be sucked into the folds:
Flame of the torch needs to have sharp center part:
Overheating the piece will create not so nice results:
That part was still salvable thou. Nice thing in silver work is that many errors you make can be corrected :)
Acidify the piece in order to get rid of all impurities in it. It will create milk white piece.
File the piece into correct height and then solder a bottom plate to the billet:
After adding soldering it looked like this:
Adding solder to the part ( soldering liquid, flux, looks white after it is heated ):
And acid bath:
Top piece can have stamp which tells that the piece is silver and also some other information ( like where it was made ):
Hitting the metal with the stamp bends it, so it needs to be straightened before the piece is soldered into the forming cube. This can be done with careful soft hammering or with a machine.
Straightened top with rest of the cube: Soldered together:
After soldering the last piece, one must be careful when acifying the part: if there are any bubbles coming from the part, it means there is a hole, and the part needs to be taken out from the liquid immediately.
The liquid needs to be taken out from the cube by drilling a hole into it. One can heat the cube a bit in order to get all of the acid out. The made hole and the existing fault in the soldering needs to be then fixed:
Wire that was pulled to match the dimeter of the hole to block it. Piece of the wire was the soldered into the hole and more solder was added to the bad solder.
Note: never be on the way when soldering the wire: it can explode if there is any liquid still inside and the wire will shoot out with huge velocity and force!
No more bubbles coming from the cube:
Then it is all about filing the part into cube with correct dimensions:
Surface finish can be done with various techniques which we will not go through here. :)
Sandpapered cube got bit less sharp edges with this tool that also made the edges shiny which give nice contrast to the otherwise mat finish.
Fixing the messed up part:
As this really is not the wanted shape, one can hammer it into better form: ( Same method can also be used if the billet not have perfect dimensions otherwise. )
While filing the deep grooves of the part came easily visible:
These grooves got more material into them with welding: