STAINLESS STEEL SLOTTED SET SCREWS CONE POINT DIN 553

Slotted Set Screws Cone Point DIN 553 — A cone point set screw takes a different approach to holding a shaft than either the cup or flat point: rather than biting into or bearing against a plain surface, its sharp, tapered tip is designed to seat into a matching drilled dimple in the shaft, wedging home as the screw is tightened to resist both axial movement and rotation through positive mechanical engagement. That gives cone point the most precise and repeatable location of the three point types, which is why it's specified wherever a fixed, semi-permanent locating job matters more than quick adjustability — collars and hubs that must return to exactly the same position after servicing, index and alignment fittings, and machinery where a component must not creep axially along its shaft under running load. The requirement for a pre-drilled dimple is the key limitation: without one, a cone point only contacts the shaft at a single line or point, giving noticeably worse holding performance than a cup or flat point would achieve on the same plain surface, so it's not the right choice for a shaft that hasn't been prepared for it. Grade selection follows familiar reasoning: A2 is fine for general indoor machinery, while A4 suits equipment in marine, washdown, or chemically active environments, particularly since a corroded cone tip loses its precise geometry more visibly than a cup or flat point would, undermining the locating accuracy that's the whole reason for choosing this point type. DIN 553 specifies the thread, cone angle and slot dimensions, keeping the point geometry consistent enough that it reliably matches a correspondingly sized dimple regardless of manufacturer. Selecting the right screw means first confirming a matching dimple exists or can be drilled in the shaft, then sizing diameter to the tapped hole and length so the cone seats fully in the dimple without the screw bottoming out in the collar first — on a plain, undrilled shaft, a cup or flat point set screw will perform far better than a cone point forced to make do without its intended locating feature.

FAQs
How deep or wide should the locating dimple be?
The dimple should be sized to suit the cone angle and diameter of the specific screw so the tip seats fully rather than bottoming on a shallow dimple or bridging a too-wide one; this is normally matched to the screw manufacturer's guidance for the size in use rather than a single universal figure.

Can a cone point set screw be swapped for a part-thread (DIN 427) type instead?
The DIN 427 part-thread version uses a cylindrical pilot rather than a tapered cone to locate into a hole, giving a different fit characteristic — generally a straighter, less self-centring engagement than a cone point's wedging action, so the two aren't simply interchangeable for the same dimple geometry.

Does a cone point resist axial movement better than rotation?
It resists both reasonably well because the wedging action engages the full taper against the dimple walls, but its strongest advantage over cup or flat points is precise, repeatable positioning — a factor that matters most where a component must return to exactly the same spot after being removed and refitted.

What happens if the dimple is drilled off-centre or too shallow?
The cone won't seat evenly, reducing both the locating accuracy and the holding force compared with a correctly sized dimple, and may leave the screw slightly proud or cause it to bottom out in the collar's tapped hole before making full contact.