STAINLESS STEEL SLOTTED CAPSTAN SCREWS DIN 404

Slotted Capstan Screws DIN 404 — A capstan screw takes the tool-free principle of a wing screw a step further: instead of finger-and-thumb wings, a cross-drilled head accepts a tommy bar or T-bar, giving considerably more leverage — and higher achievable hand torque — than wings alone can provide. DIN 404 retains a straight slot as a secondary drive option alongside the cross-drilled holes, so the screw can still be turned with a standard screwdriver when a bar isn't available, though the bar-driven method is the primary intended operation wherever higher torque is needed. Typical applications include adjustment points on machine tools and equipment, valve, clamp and fixture settings needing repeatable hand tightening, and anywhere access is too restricted for a standard screwdriver but a bar can still be inserted through the head.

The choice between a capstan screw and a wing screw comes down to how much torque the joint actually needs: wing screws suit lighter, purely hand-tight fixings, while capstan screws are specified where a controlled, repeatable hand torque beyond finger pressure is required, but a powered driver is either impractical for the environment or undesirable for the application — operator-adjusted settings that shouldn't be over-tightened by an unfamiliar power tool are a common reason to specify this style.

DIN 404 fixes the head diameter, cross-hole sizing, slot dimensions and thread length for the standard range, giving a consistent part across suppliers. Grade selection follows general practice: A2 stainless suits indoor adjustment points in dry conditions, while A4 is worth specifying for equipment operating outdoors, in washdown environments, or wherever the adjustment point sees frequent handling in a corrosive setting, since stiffness from surface corrosion works directly against the tool-free, repeatable adjustment this head style exists to provide.

Match the thread to the tapped hole or nut, and check that there's enough clearance around the head for a bar to be inserted and swung through its full arc before specifying this style over a wing screw.

FAQs
Can a capstan screw be driven with a standard screwdriver?
Many DIN 404 capstan screws also include a straight slot as a secondary drive, allowing use with a screwdriver as well as a bar, though the bar-driven method is the primary intended operation for higher torque.

Why use a capstan screw instead of a standard driven screw?
Capstan screws suit applications where a controlled, repeatable hand torque is preferred over a powered driver, such as adjustment points intended for operator use without tools, or where the surrounding environment makes powered tools impractical.

Is there a size limit on the bar used to drive a capstan screw?
The bar diameter needs to match the cross-drilled hole in the screw head; an oversized bar won't fit, while an undersized one reduces the leverage advantage the design is meant to provide, so check the hole size against available bar stock before specifying.