Mouse Vader
Sr Member
Still in the same boat doing stuff wise so here's a little digression on screw names (from a UK perspective). We see the term set screw, grub screw & bolt often enough on these pages but I remember well the withering gaze I received many moons ago when I tried to buy some threaded fasteners which I called (I think) set screws when what I really wanted was bolts. I thought he was going to throw me out the shop.
In general there are : wood screws - that drive directly into wood or a pilot hole cutting their own thread as they go ; set screws - usually for metal & fix into a pre-made & tapped (threaded) hole ; bolts - used with nuts.
Each of these categories can have a multitude of different head types. I'll just deal with set screws & bolts here.
The most reliable way to tell a set screw from a bolt is that a set screw is threaded for the entire length of the shank eg. this flat head set screw (aka countersunk).
& a bolt has an un-threaded part before the head this eg. hex head bolt (not to be confused with an allen head/socket).
If I recall properly the threaded part on a bolt is a set length, so many times the shank's diameter, so that, say, a 3 inch long 1/4 inch bolt will have the same length of thread as a 2 inch long 1/4 inch bolt & it's the length of the un-threaded part that varies & you can see that a very short bolt will have little to no un-threaded portion & look like a set screw...
To confuse things there is nothing stopping a set screw being used like a bolt - with a nut - but it is still a set screw. Likewise a bolt can be used like a set screw but it's still a bolt.
So what about grub screws ? These are (in UK) a specifically named type of set screw ie. a headless set screw. They have a fully threaded shank & no head, just an (hexagonal) allen socket or simple slot.
And lastly to confuse things even more specific industries (& countries) often have specific names for specific types of set screw & bolt. eg. machine screws (I think, in UK) are set screws below 1/4 inch diam.
Hope you found that interesting / useful.
In general there are : wood screws - that drive directly into wood or a pilot hole cutting their own thread as they go ; set screws - usually for metal & fix into a pre-made & tapped (threaded) hole ; bolts - used with nuts.
Each of these categories can have a multitude of different head types. I'll just deal with set screws & bolts here.
The most reliable way to tell a set screw from a bolt is that a set screw is threaded for the entire length of the shank eg. this flat head set screw (aka countersunk).
& a bolt has an un-threaded part before the head this eg. hex head bolt (not to be confused with an allen head/socket).
If I recall properly the threaded part on a bolt is a set length, so many times the shank's diameter, so that, say, a 3 inch long 1/4 inch bolt will have the same length of thread as a 2 inch long 1/4 inch bolt & it's the length of the un-threaded part that varies & you can see that a very short bolt will have little to no un-threaded portion & look like a set screw...
To confuse things there is nothing stopping a set screw being used like a bolt - with a nut - but it is still a set screw. Likewise a bolt can be used like a set screw but it's still a bolt.
So what about grub screws ? These are (in UK) a specifically named type of set screw ie. a headless set screw. They have a fully threaded shank & no head, just an (hexagonal) allen socket or simple slot.
And lastly to confuse things even more specific industries (& countries) often have specific names for specific types of set screw & bolt. eg. machine screws (I think, in UK) are set screws below 1/4 inch diam.
Hope you found that interesting / useful.
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