About John: John is a Syzjewelry jeweler and business owner with 13 years of jewelry-design experience. This guide shares how I file a casting and why I stop where I do.
I file in two grits: 240-400 to take out the file marks, then 600-1000 to refine.
The numbers I work to
- First pass, file marks out: 240-400 grit.
- Refining pass: 600-1000 grit.
- Prong diameter after filing: keep it above 0.45 mm.
- Shank: every 0.1 mm removed from a 1.5 mm shank takes off about 7% of its cross-section.
Why I stop early
Filing is where a ring is made thinner than it was drawn. A tenth of a millimetre looks like nothing on the bench. On a 1.5 mm shank it is about 7% of the metal, and it comes off the part that carries the ring.
What goes wrong
A prong filed under 0.45 mm looks fine and lets go of the stone later. I measure after I file.
Using this on a tools page
The tools on this page, such as burs, stone-setting pushers, a bezel roller and a wood ring clamp, are bench tools for setting and holding work. If you finish your own pieces, the rule above is the same: measure after you file, not before.
Figures are ranges from my own bench notes. Actual practice follows each workshop's process card, order requirements and the current standard.