Polymetric Machine — High-Precision Faceting for the Demanding Cutter
Polymetric Machine — High-Precision Faceting for the Demanding Cutter
A North American faceting machine known for rigid construction and repeatable angle precision
The Polymetric machine is a high-precision faceting machine produced by Polymetric Instruments, a North American manufacturer with a long-standing reputation in the faceting community. The machine is designed for the demanding work of competition cutting, original-design faceting, and high-grade commercial production where the operator requires repeatable angle and height accuracy at the limits of mechanical fabrication.
Construction and accuracy
The Polymetric machine is built around a rigid mast and a precision-machined head that supports the dop and quill assembly. The mast is the principal source of accuracy; any flexure in the mast translates directly into facet variation, and the Polymetric design uses a heavy mast with minimal compliance to maintain repeatable position under the cutting forces of normal lap work. The head supports an index gear with the standard 96-position index plus auxiliary indexes for non-standard cuts, and the angle scale reads to 0.01 degree on the production model.
The height adjustment, which controls the depth of cut on each facet, is similarly graduated to high resolution, allowing the cutter to set facet meet-points by mechanical setting rather than by visual judgement alone. The combination of fine angle control and fine height control is what enables the production of repeatable, geometrically clean facet patterns at the level demanded by competition cutting.
Lap and dop systems
The Polymetric machine accepts a range of lap sizes, with 6- and 8-inch laps the standard, and a range of dop systems including the conventional cold dop and the more recent transfer-jig dop arrangements. The motor drive is generally a variable-speed direct-drive system that allows the cutter to slow the lap to a few hundred rpm for fine polish work or run faster for cut-down. Water and slurry feed are integrated into the lap area to keep the cutting interface lubricated and the lap clean.
Position in the market
The Polymetric machine sits within a small group of premium faceting machines that includes machines produced by Facetron, Ultra Tec, and a handful of other manufacturers. Each has its partisans within the cutting community, and the choice between them is influenced by the kind of work the cutter does most often, the price tolerance of the customer, and personal preference. Polymetric machines are particularly favoured for high-precision design work and for situations where the cutter expects to maintain the machine over decades of use; the build quality is matched to a long service life with periodic maintenance.
In the trade
A Polymetric machine represents a substantial investment, and the machines are most often found in the workshops of professional or serious-amateur cutters who produce original-design or competition work. Commercial cutting houses producing standard rounds and ovals typically use less expensive machines optimised for production speed; the Polymetric is the machine of choice where the precision of each individual stone matters more than the throughput of the operation as a whole. Used Polymetric machines retain their value well in the secondary market and are often the entry point for working cutters who cannot justify the cost of a new machine.