Balls HK35 black

The ball on the lever is one of the oldest ergonomic solutions in the workshop, and Ball knobs HK35 are the classic version: a handle ball in bakelite with a glossy surface and a threaded hole, in a design similar to DIN 319. The ball screws onto the threaded end of the lever and gives the hand a round, grip friendly finish that works at any angle.

The series spans 29 versions. The diameters run from 16 to 50 mm and the threads from M4 to M16, with several thread options per ball size; a 25 mm ball, for example, comes with a thread in M5, M6, M8 or M10. All of them are black with a glossy surface, and you pick the combination of diameter and thread as a variant on the product page.

Bakelite is a thermoset, and that is not a nostalgic choice but a technical one. The material is hard, stiff and dimensionally stable; the ball is not deformed by years in a hard grip, and the glossy surface stands up to oils, cutting fluids and solvents found around machine tools. The thermoset does not soften from heat the way thermoplastics do either, which is felt near warm machine parts. The surface is also easy to wipe clean, and the color does not sit on the outside; black bakelite is colored right through. The density of the material gives the ball a certain weight in the hand, a feel many operators prefer over lighter plastic balls.

The glossy surface has a functional reason. On a lever ball the hand has to be able to slide and change grip in the middle of a movement, unlike a pull handle where friction is the goal. Glossy bakelite gives exactly that dry, smooth feel that generations of operators recognize from lathes, milling machines and control levers.

The uses are the same today as fifty years ago: gear and control levers on machine tools, direction levers on conveyors, handles on vises and fixtures, levers on agricultural and construction equipment. When refurbishing older machines a DIN style ball is often the only part needed to restore the original feel, and in interior design the balls turn up as period style knobs.

Choose the size to match the work the lever does. Small balls of 16 and 20 mm suit finger operated controls; the middle sizes around 25 to 32 mm are standard on ordinary machine levers, and the largest at 40 to 50 mm belong where the whole hand takes hold and pulls. The thread has to match the end of the lever, and the rule of thumb is that a heavier lever gets a heavier thread; the combinations in the series follow that pattern. Unsure between two sizes? Take the larger one, since a ball that is too small tires the hand faster than one that is too large. Count on gloves as well; an operator with winter gloves needs a few millimeters more ball than one with bare hands.

Assembly is simple and needs no tools: screw the ball on by hand until it stops. Bakelite is harder but more brittle than nylon, so do not tighten with pipe pliers and avoid knocks; if the joint has to be secured, use thread locking fluid. Check that the thread length of the lever does not exceed the depth of the hole, otherwise the lever bottoms out before the ball is seated.

The balls are supplied by the pack, from 500 pieces for the small sizes down to 50 for the largest. If you prefer a ball in nylon with a metal thread, HK30 bushing with a brass thread in M8 or M10 is in the range.

Would you like to compare bakelite with nylon for your lever? Call us and we will talk the choice through.