Knobs HC30 smooth hole black

The same knob body, a different mounting. Knobs HC30 plain hole are cylindrical handle knobs in nylon PA6, 25 mm in diameter and 30 mm high, where the mounting is a plain hole in 6, 8 or 10 mm instead of a thread. The knob is pressed onto a plain shaft or bar end, which makes it the quick option when there is no threaded stud to screw onto.

A plain hole has a logic of its own. Cut round bars, bent wire blanks and plain control rods often have no thread, and threading them afterwards costs one operation per part. With a press fitted knob that step disappears; cut the bar to length, press on the knob and move on. In the production of jigs, actuators and simpler controls that saves both time and tooling. The same goes for prototype work; a press fitted knob is in place seconds after the bar is cut, and can be knocked loose again if the control needs adjusting.

The hole is 17 mm deep according to the manufacturer's data sheet, which gives good contact against the bar without the knob having to bottom out. If you want to secure the mounting further, the usual methods work: light knurling of the bar end, an adhesive intended for nylon, or a cross drilled roll pin if the knob has to take hard pulling. It is worth trying the fit on a test piece first; a press fit stands or falls with the real diameter of the bar, not with the nominal dimension.

The pressing itself is best done in an arbor press or a vise with soft jaws, with the force straight along the direction of the bar. If you hit the knob with a hammer you risk both crooked holes and white stress marks in the plastic. If assembly is stiff it helps to warm the knob gently in hot water; the nylon then becomes a little more yielding and creeps into place without brute force.

The material is the same PA6 as in the threaded version of the series. The nylon is tough and impact resistant, handles drops on the floor and knocks from tools without cracking, and the matte black surface hides dirt in a workshop. The surface is closed; oil and grease are wiped off with a cloth. The moisture that nylon draws from the air does not affect the function of a grip, that is a property to care about in dimensionally critical machine parts, not here.

The uses overlap with those of the threaded version: end knobs on levers and pull rods, handles on doors and guards, grips on fixtures and test setups. The difference lies in what the knob meets. A threaded stud, pick HC30 bushing. A plain bar, pick this one. Simple as that. And if you do need a threaded mounting later, you can switch to the bushing version without the feel in the hand changing.

The three hole sizes cover the most common bar diameters in lighter controls: 6, 8 and 10 mm. The outside dimensions are identical between the versions, so you can keep the same feel in the hand across the whole machine even if the bars vary in thickness. That helps maintenance as well; one and the same knob in the store fits several places.

The knobs are supplied in packs of 500 pieces, a volume aimed at OEM assembly and larger maintenance stores rather than one-off builds. For anyone designing something new it is worth knowing that the series also holds threaded versions and mushroom shaped push knobs, so all the grips on a machine can come from the same family.

Not sure which hole version suits your design? We will gladly help you.