STAINLESS STEEL SLOTTED SET SCREWS PART THREAD DIN 427

Slotted Set Screws Part Thread DIN 427 — DIN 427 shares its flat, chamfered point profile with the DIN 551 flat point screw, but stops the thread short of the slotted end, leaving a plain, cylindrical pilot section that's designed to seat into a matching hole or recess in the shaft rather than bear against a plain flat surface. That pilot changes how the screw locates: instead of relying on the point's own shape to grip or seat, DIN 427 depends on a close fit between its plain shank and a prepared hole, giving a more positive, straighter engagement than a tapered cone point on longer sizes, and useful where the fitting needs a cylindrical rather than conical locating feature. It's specified in similar territory to the cone point range — collars, hubs and fittings that need precise, repeatable positioning on a shaft — but is particularly relevant on longer screw sizes, where the proportion of plain shank to threaded length increases in line with the standard's sizing table, reducing the risk of cross-threading over that extended length compared with a fully threaded screw. Grade selection follows the usual pattern: A2 for general indoor machinery, A4 where the assembly faces marine, washdown, or chemically active conditions, since maintaining the pilot's precise fit matters as much as avoiding general corrosion, and a pitted pilot section will seat less reliably in its mating hole over time. Choosing the right screw starts with confirming a matching hole or recess exists in the shaft or fitting, sized to accept the pilot's diameter; length then needs to be checked against the DIN 427 dimension table for the size in use, since the plain-to-threaded proportion changes with overall length rather than staying fixed. Where no prepared hole exists and a fixed locating feature isn't practical, a cup or flat point set screw threaded to the tip is a more straightforward specification than trying to adapt a part-thread screw to a plain shaft.

FAQs
Is a part thread set screw reusable?
Yes — because location comes from the pilot fitting into a prepared hole rather than from surface indentation, it can generally be removed and reinstalled without the loss of locating accuracy that a cup point can suffer from repeated retightening in the same spot.

How does the plain-to-thread ratio change with screw length?
Longer sizes carry proportionally more plain shank relative to thread than shorter ones, following the DIN 427 sizing table, so the exact thread length for a given nominal size should be checked against that table rather than assumed from a similar screw of a different length.

What's the benefit of a cylindrical pilot over a cone point on long screws?
A cylindrical pilot maintains a consistent bearing fit along its length in a matching hole, which can be more stable on longer screws than a cone point's single tapered contact line, particularly where the fitting needs to resist slight misalignment rather than rely purely on a wedging action.

Can DIN 427 be used without a prepared hole in the shaft?
Not effectively — like the cone point version, its performance depends on the pilot seating in a corresponding hole or recess; on a plain, undrilled shaft, a cup or flat point set screw threaded to the tip will perform more predictably.