When a ring only needs to be sized down by a small amount, you can easily size the ring by compression. This is the perfect way to size a plain ring that doesn’t have any gemstones and is made of only one type of metal, as it will save you time and money.
Before beginning, it is very important to check both sides of the ring on a mandrel to be sure that they are both the same size.
You will first want to anneal the metal, as this will make the stretching process ten times easier as the metal will be more malleable and less likely to crack under pressure. It is best to fire coat the ring to protect the finish before annealing. Heat the ring with a soft flame; this will cause the fire coat to seal on the ring. Continue heating to anneal the ring, when the metal glows faintly red you have reached annealing temperature and you can quench the ring in water.
Once the ring is quenched, place the ring in the pickle to remove the boric acid coating. Rinse and dry the ring before enlarging the ring.
We will now make use of your bench mounted ring sizer. The lower half of this device is designed specifically for compressing rings. Measure the ring’s current size on a ring mandrel and then, through trial and error, place the ring in the die of the mandrel that allows the ring to enter most of the way, with just a bit of the ring exposed.
By lowering the lever on the side of the tool, you lower the mechanism and begin pressing the band into the die. You want to work in very small increments to avoid over-compressing the ring. Raise the lever and take the ring out of the die.
Check the size of the ring on a mandrel. Remember, that one side of the ring has been compressed more than the other, so be sure to measure both sides. Flip the ring over so that the larger side can be compressed and repeat step 5 in the same die.
Repeat steps 5 and 6 until the ring reaches the desired size by placing the ring in progressively smaller dies.
The more the ring is compressed, the more stress distortion it will show. To account for this buff and polish the ring to restore it to its original luster.