Oil Reservoir — Coolant Supply for the Faceting Lap
Oil Reservoir — Coolant Supply for the Faceting Lap
The drip system that keeps lap and stone cool during cutting and polishing
An oil reservoir is the small container, drip bottle, or pump-fed tank that supplies oil-based coolant to a faceting lap during cutting and polishing. Without a steady film of oil or other lubricant on the lap surface, the diamond abrasive heats the stone to temperatures that can fracture cleavage-prone material, glaze the lap, and shorten the working life of both lap and abrasive. The reservoir is therefore a working part of the cutting station rather than an accessory.
Form and operation
Most reservoirs in small workshops are simple gravity-fed bottles suspended above the lap, with a needle valve or pinch clamp regulating the drip rate. Larger production setups use small electric peristaltic pumps that deliver a measured flow under more consistent pressure. The fluid is most commonly a light mineral oil such as a baby-oil grade, a proprietary cutting oil thinned with paraffin, or a water-soluble extender suited to resin-bonded laps. The cutter chooses the fluid to match the lap and the stage of cutting: heavier oils dampen vibration on coarse cutting laps, while polishing laps run with lighter, cleaner fluids that are easier to clean off the polished facet.
Adjusting flow
A correctly set reservoir delivers just enough fluid to keep the lap visibly damp without flooding the work. Too little flow and the lap glazes, the stone heats, and surface scratches deepen rather than removing; too much flow and the swarf is washed away before it can do useful cutting work, abrasive is wasted, and the cutter's view of the stone is obscured by spray. Most experienced cutters develop a feel for the correct setting by sound and by the appearance of the swarf line on the lap.
Care and housekeeping
Oil reservoirs accumulate swarf and need periodic cleaning. The drip line, in particular, can clog with fine particulate and should be flushed regularly with solvent. A clean reservoir also reduces the risk of cross-contamination between coarse and fine laps, which in a small workshop typically share a single cutting station.