Knobs HC35 black

A lever without a knob is a half finished part. Knob HC35 is a handle knob injection molded in PA6 (nylon 6), black with a glossy surface, and it is fitted on levers, control arms and pull controls where the hand needs a firm and comfortable end to grip. The difference between a good and a bad knob does not show in the catalogue but in the hand, fifty times a shift; the right diameter, the right height and a material that is neither cold nor slippery make the movement a non-event, and that is exactly what a control should be.

The knob is 32 mm in diameter and 44 mm high. The hole is plain, that is unthreaded, and comes with a diameter of 8 or 10 mm; the hole depth is 20 mm for the 8 mm hole and 33 mm for the 10 mm hole. The top has a cover window where a symbol or logo can be printed, handy when the lever has to be marked with a function or a warning symbol.

PA6 is the standard material for this kind of machine element, and that is no accident. The nylon is tough and impact resistant, so a knob that takes a hit from a falling tool springs back instead of cracking. The material stands up to oils, greases and most of the lubricants found in a machine shop. The surface also keeps its look after years of skin contact, unlike painted metal knobs that get rubbed shiny at the most used spot. Nylon conducts heat poorly as well, so the knob never feels ice cold to grab during the winter months in a half heated building.

The plain hole is a point in itself. The knob is pressed onto a turned shaft end and can be twisted to exactly the right position before it is fixed, which is hard with threaded knobs that stop where the thread stops. For permanent assembly a press fit with a few hundredths of interference is often enough; if you want to be able to remove the knob, the stud can be glued with an anaerobic adhesive or given a light knurl. Check the hole size against the real diameter of the stud, not against the nominal dimension on the drawing. A stud turned a few hundredths under gives a loose knob, and it is worth keeping the end of the stud chamfered so that assembly goes in straight.

Knobs of this type sit on feed handwheels and locking levers in lathes and milling machines, on shift levers in older machines, on actuators in packaging machines and on controls in agricultural and construction machinery. Designers draw them in as a standard component in new machines; maintenance departments replace them when the originals have cracked, gone missing or simply feel unpleasant to touch. In public settings they turn up on everything from parking machines to exercise equipment, but the shop floor is home ground.

The size decides the grip. A knob under 30 mm is handled with the fingertips and suits controls that call for feel, while the larger diameters are filled by the whole palm and suit levers that are pulled with force. Think about where the knob ends up in the working area of the machine as well; a knob that sticks out into a walkway had better be round and smooth than large and angular.

HC35 is supplied with 500 knobs per pack, a volume that works both for series production and for the spare parts shelf. It is worth keeping the same knob model across the whole machine; it gives a uniform impression and simplifies spare parts holding. The other knob models in the series have different diameters, heights and top details, so it is worth comparing before you decide.

Not sure which hole size suits your shaft end? Get in touch with us.