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🔩Small but vital, a grub screw is what stops a pulley or knob spinning on its shaft. Get the point and size right and it holds fast. Here is how they work.
A grub screw is a small, headless screw that does an important job: locking one part onto another, like a pulley, gear or knob onto a shaft. Also called a set screw, it sits flush or below the surface and clamps down to stop things slipping. Choosing the right point and size is what makes it hold.
This guide covers what grub screws are, the common drive and point types, and where they are used.
📌Quick summary
A grub screw is threaded along its whole length with no head, which is why it is often called a headless screw. It threads into a tapped hole and its tip presses against a shaft or mating part to lock it in place. Because there is no head, it can sit flush or below the surface, out of the way.
Most grub screws are socket set screws, driven with a hex, or Allen, key. The recessed socket lets you apply good torque in a compact fitting, and it keeps the drive flush. That is why Allen key grub screws are the standard for locking collars, pulleys and knobs.
The tip of a grub screw comes in several styles for different jobs. A cup point bites into the shaft for a strong grip and is the common all-rounder. A cone point digs in hard for a near-permanent hold. A flat point suits soft or frequently adjusted parts, and a dog point locates into a hole or slot. Choosing the point is the key decision.
For the best hold, many shafts have a flat machined where the grub screw lands, giving the point something solid to bite. That stops the part creeping around the shaft and is worth doing on anything that carries load or vibrates.
💬Not sure which point or size you need? The team at Select Fasteners in Heatherbrae can point you the right way. Give them a call on (02) 4020 7951.
Grub screws are everywhere once you look: locking pulleys, gears and sprockets to shafts, holding door knobs and handles, fixing shaft collars, and securing bearings. Anywhere one part needs to stay put on another without a protruding head, a grub screw is the answer.
Grub screws come in a wide range of thread sizes and lengths, and the screw has to suit both the tapped hole and the shaft. Too long and it bottoms out or protrudes, too short and it will not reach. Bring the old screw or the part in and our team can match it.
Select Fasteners carries screws from trusted brands including Bremick and Hobson as part of our fasteners range. The trade specialist team at the Heatherbrae store has decades of experience and can help you find the right grub screw for the job.
You will find the rest of the screws and fixings you need in the same shop, so you can sort it all in one trip.
A grub screw is a small, headless set screw threaded along its whole length. It threads into a tapped hole and presses against a shaft or part to lock it in place, so it can sit flush or recessed without a protruding head.
They are essentially the same thing. Grub screw is the common name for a headless set screw driven with an Allen key. The term set screw can be broader, but in everyday use the two names refer to the same fastener.
Most are driven with a hex or Allen key that fits the recessed socket. Thread it into the tapped hole until the point presses firmly against the shaft or part. A machined flat on the shaft gives the point something solid to bite for a better grip.
A cup point is the common all-rounder that bites the shaft. A cone point digs in for a near-permanent hold, a flat point suits soft or frequently adjusted parts, and a dog point locates into a hole or slot. Match the point to the job.
Match the thread size to the tapped hole and the length to the fitting, so the point reaches the shaft without bottoming out or protruding. If you are unsure, bring the old screw or the part in and our team can match it.
Usually it is not biting a solid surface, or it is the wrong point or size. Machine a flat where the point lands, choose a cup or cone point for grip, and on parts that vibrate consider a thread-locking product.
A small screw does a big job when it is the right one. The team at Select Fasteners in Heatherbrae will match the right grub screw, point and size to your fitting.
Give the team a call on (02) 4020 7951, drop by the store at 1 Archibald Place, Heatherbrae, or send us an online enquiry!
We supply fasteners, fixings and trade supplies across Port Stephens, Newcastle, the Hunter Valley and Dungog, with the largest range north of the Hunter River.
Select Fasteners is a specialist fastener and industrial supplies business based at 1 Archibald Place, Heatherbrae NSW, serving Port Stephens, Newcastle, the Hunter Valley and Dungog. This article is general information only and does not account for the specific conditions of your project. For advice specific to your job, get in touch with the team.
02 4020 7951
