Ergonomics for Bench Pin Modifications

Ergonomics is the safe and effective relationship between a worker and the work environment. For the bench jeweler who spends hours working with a bench pin, it is important to make it work efficiently and effectively for you. There are many modifications you can make to ensure this.

People prefer different bench pins, namely a flat piercing pin vs. an angled working pin. Some modifications can be used with either type, while others work better with a specific style of bench pin.

To modify a working bench pin, start with a standard wedge-shaped bench pin, measuring 133 x 59 millimeters. These are available at most jewelry tool suppliers. With the angled side facing up, draw a 15 mm long line, 13 mm in from the left edge. Make a mark 61 mm back from the front right edge and draw an angled line from that point to the end of the first line. The wood on the right side of the lines is cut away to leave the basic shape of the working bench pin. The 15 mm line is cut with a perpendicular cut. The angled line is cut at 45 degrees, tilting away from the front top, leaving a slanted surface. Holding items against that edge makes filing easier.

Whichever type of bench pin you use, the best place to start is with a piece of sandpaper. Simply smoothing the surface of the wood and gently rounding corners will make a difference you'll feel immediately as your hands come in contact with the bench pin.

To help the bench pin hold a ring clamp securely, sand interlocking grooves with a 25 mm sanding band in the bench pin and the ring clamp. Sand the bench pin at the intersection of the first two cuts, leaving a semicircular arc with vertical sides. On the ring clamp, measure down 10 mm from each end and draw a line around the body. Sand a groove in the ring clamp following this line to create a lip at the end that will catch on the bench pin and hold it steady when in use. Sand the ring clamp groove until it mates nicely with the arc on the bench pin.

A ring-cutting fixture at the end of the bench pin is invaluable (Figure 1). To create one, file an 8-mm-wide groove in an arc around the squared end of the pin, 5 mm from the front edge. A ring shank will slip over this 5-mm-wide lip and be secured straight and square while you cut it for size. Next, use a No. 2 blade to cut a straight vertical slot into the end of the bench pin. Your saw will follow this slot when you cut ring shanks. You can also file a relief notch at the top center of the lip of the ring-cutting fixture with the narrow edge of a flat hand file centered on the saw cut. This will open up sight lines so the area you are cutting will not be obscured behind the lip of the fixture. This modification increases the accuracy of the cut and the efficiency of the operation while reducing the possibility of slipping, broken blades and injury.

You can also prevent rings from sliding on the bench pin while filing the insides of shanks by making a set of three grooves. Use a ball bur to cut the grooves — 2 mm, 6 mm and 10 mm wide — in the top of the bench pin, just behind the angled diagonal cut. Each groove should be 12 mm long and aligned with the diagonal cut, side by side, parallel with the angled top edge. They should be 1-2 mm deep with at least 5 mm between them. This modification enables the jeweler to file flat inside ring contours.

A stone-holding tray can also be incorporated into the flat top of the bench pin. Mark a 12 x 22 mm rectangle and use a ball bur to carve out a shallow depression to hold the stones.

A similar feature can be added to the right side of the bench pin to hold cutting lubricant. Mark a 10 x 10 mm square and use a ball bur to carve a shallow depression, just like the one in the stone tray. Melt the cutting lubricant into the depression with a soft flame. Slightly overfill the cavity, and when it cools you can quickly wipe the cutting lubricant from your saw blades, burs and twist drills.

The more you specialize your tasks at the bench, the more specialized your modifications will become. Left-handed bench jewelers can simply mirror the locations and orientations of most of these modifications. As you continue to work, keep in mind that a few minutes with a file, bur and square- or straight-edge tool can make a significant difference in how well your bench pin works for you.

By GIA’s Jewelry Manufacturing Arts instructors

© GIA – 2012

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