Our slotted flat point set screws have a flat, square cut tip that clamps against a shaft or flat without digging in. The straight slot drives with a standard blade screwdriver, and the headless body sits flush or below the surface, which makes these the go to choice for collars and hubs that need frequent repositioning.

Slotted Set Screw Flat Point, Metric Sizes

What Is a Slotted Flat Point Set Screw?

A slotted flat point set screw, often called a grub screw, is a headless threaded fastener with a straight driving slot at one end and a flat, square cut face at the other. It threads through a tapped hole in a collar, hub, pulley, or knob and bears down on the mating shaft, holding it by friction from the clamping force rather than by penetrating the surface. The flat point is the least aggressive of the standard tip forms, so it leaves the shaft essentially unmarked and lets the component be loosened, repositioned, and retightened many times over. That makes it the natural choice for parts that get adjusted in service, for thin walled tubes and soft shafts that a cup or cone point would gouge, and for seating on a machined flat or against a hardened shaft. The screw is manufactured to DIN 551 in the plain flat point form and to DIN 438 where a flat point with a slot and a longer body is required.

Key Features and Benefits

• Non Marring Flat Tip: The square cut face spreads clamping load over its full area, so the shaft stays smooth and can be reused or repositioned freely.
• Repeatable Adjustment: Because the tip does not bite, collars and hubs can be moved and reset repeatedly without wearing a track into the shaft.
• Straight Slot Drive: A common blade screwdriver drives the screw, so field service needs no hex keys or special bits.
• Fully Headless Profile: The screw seats flush or below the outer surface, removing snag points on rotating collars, knobs, and handwheels.
• Ideal for Machined Flats: Where the shaft has a ground flat, the flat point mates face to face for maximum contact area and holding force.
• Safe on Soft and Thin Materials: Suits brass, aluminium, plastic, and thin walled tube where a pointed tip would deform or pierce the wall.

Materials and Finishes

• Carbon Steel, Plain or Zinc Plated: The standard grade for general machinery, collars, pulleys, and knobs in dry indoor service.
• Alloy Steel Class 45H: Hardened for higher clamping torque in loaded drive components.
• Stainless Steel A2 (304): For food equipment, damp areas, and general corrosion resistance.
• Stainless Steel A4 (316): For marine and chemical environments with heavier corrosion exposure.

Standards Compliance

• DIN 551, slotted set screws with flat point
• DIN 438, slotted set screws with flat point, longer thread form
• ISO 4766, slotted set screws with flat point international equivalent
• ISO 898 Part 5, mechanical properties of set screws and similar threaded fasteners

Size Range and Availability

Available in M3 through M12 in metric coarse thread with lengths from 3mm to 40mm, in plain and zinc plated steel, hardened alloy steel, and A2 or A4 stainless.

Frequently Asked Questions (FAQs)

1. What is a flat point set screw used for?

It clamps a collar, hub, pulley, gear, or knob onto a shaft without marking it, which suits assemblies that get repositioned in service and shafts that are soft, thin walled, or hardened.

2. When should I choose a flat point instead of a cup point?

Choose the flat point when the shaft must stay unmarked, when it is hardened so a cup point cannot bite, or when the screw seats on a machined flat. Choose a cup point when maximum holding on a plain soft shaft matters more than surface finish.

3. Does a flat point set screw hold as well as a cup point?

On a plain round shaft the cup point holds more, because its edge bites into the surface. On a machined flat, the flat point matches or beats it thanks to the full face contact area.

4. What is the difference between DIN 551 and DIN 438?

Both are slotted flat point set screws. DIN 438 covers a longer threaded body for deeper tapped holes, while DIN 551 is the shorter standard form.

5. Are set screws and grub screws the same thing?

Yes. Grub screw is the common workshop term for a headless set screw, and the two names refer to the same fastener.

6. Will a flat point set screw loosen under vibration?

It can, since it holds by friction alone. Use a thread locking compound, a jam nut, or a second set screw at ninety degrees where vibration is significant.

7. What screwdriver fits a slotted set screw?

Use a parallel tip blade driver that fills the slot width and depth. A tapered household blade rides up and out of the slot and rounds the edges, which is the usual cause of a chewed set screw.

8. Can I use two set screws in the same hub?

Yes, and it is common practice. Two screws spaced at ninety degrees resist rotation and axial slip better than one, and give redundancy if the first backs off.

9. How tight should a set screw be?

Tighten to the torque for the screw size and grade rather than by feel, since these small diameters are easy to snap. On soft shafts, over tightening also deforms the shaft even with a flat point.

10. What sizes do you stock?

We stock M3 through M12 in metric coarse thread with lengths from 3mm to 40mm, in plain and zinc plated steel, hardened alloy steel, and A2 or A4 stainless.