|noel shelley||27/08/2021 10:22:16|
|770 forum posts|
If a bolt has thread all the way to the head and is longer than about 1" or 25mm then it is NOT a bolt - it's a set screw ! If there is plain rod between the head and the thread it's a bolt. This simple point may save some one trouble when ordering set screws or bolts. Good luck, Noel.
|Rob McSweeney||27/08/2021 10:32:31|
|60 forum posts|
Set screw? - Machine screw, surely.
|John Haine||27/08/2021 10:48:59|
|4188 forum posts|
|noel shelley||27/08/2021 10:51:27|
|770 forum posts|
Depends on which school you went to I think ? Set screw is a more descriptive term but the importany think is to get the right part for the job ! Noel.
|Andrew Johnston||27/08/2021 10:53:33|
6283 forum posts
Set screw is the correct technical term. But unfortunately sloppy definitions mean that set screw can also be used to mean a grub screw. Machine screws imply a non-hexagon head.
It's almost as bad as describing a milling machine as universal just because it has horizontal/vertical capability.
|Mike Hurley||27/08/2021 10:54:47|
|185 forum posts|
Always known them as set screws, but the term machine screw is just as ' correct ' to my knowledge. Either way, distinctly different to a bolt.
|john halfpenny||27/08/2021 11:11:52|
|189 forum posts|
I was taught (and it seems logical to me) that a macine screw is the generic term, and so called to distinguish from other types, such as wood screws. A bolt is one subset of machine screws, with plain portion of shank. A set screw is another.
|Roderick Jenkins||27/08/2021 11:25:37|
2123 forum posts
Mostly a difference between US and UK terminology I think.
86 forum posts
Isn't a bolt used in conjunction with a nut (& washer etc.) and a screw (machine, set, grub, shoulder etc.) is fitted to a threaded hole although there will be as many opinions on this as there are types of screws and bolts
|2161 forum posts|
Looks like Wiki has it wrong on this topic, not the first error on that platform. !!!!!!
|Nicholas Farr||27/08/2021 12:45:44|
3001 forum posts
Hi, I've always known set screws to be hex head that are fully threaded, a bolt has a plain shank between the head and the thread and the head doesn't have to be a hexagon e.g. coach bolt or even square head bolt, machine screws normally require a screwdriver to tighten them up. of course, all of these can and are used with or without nuts.
|21 forum posts|
At the bolt supply company I worked they were called tap bolts.
21467 forum posts
Hope they were not used in conjunction with tap washers for critical jobs
|Martin W||27/08/2021 13:56:04|
|901 forum posts|
Only if they were being fitted by the company drip .
|duncan webster||27/08/2021 14:27:10|
|3526 forum posts|
In case anyone is wondering what the fuss is about, if loaded in shear a bolt with a plain shank has a much better abutment against a round hole, and has a significantly higher shear load capacity. This implies that the plain bit should be just less in length than the thickness of the 2 bits that it is going through
21467 forum posts
You may also run into problems if you order a coach screw using Noel's definition of a bolt/screw as this is a coach bolt
And this is a coach screw
Edited By JasonB on 27/08/2021 14:59:31
|Mick B1||27/08/2021 14:59:26|
|2023 forum posts|
In the colloquial-speak I'm used to, anything with a round head - machine or wood thread, domed, cheese, flat, c/sk or cap, and slotted,Phillips, Pozi, hex socket, torq or other drive - is a screw.
Anything with a hex head is a bolt, however high or low up the shank the thread goes.
I'm not saying this is right, just that it's common parlance. I've seen enough variations - such as setscrew/grubscrew conflation as above - to think that the only way to be certain to get the right screw is to
|not done it yet||27/08/2021 16:20:14|
|6350 forum posts|
Well, for a start, I differentiate between cap-screws and cap-head bolts. The bolts have a plain section of shank. Screws are made to be screwed all the way in and secure the part on the head - that can be a hex or round. Cap heads are particularly useful when counter-bored below the surface. Bolts are generally tightened with a nut, or threaded into a different member to that which is being secured by the bolt.
I specify dependent on the situation in which the fixings are to be used. There are often alternatives, but also some specific fixings (coach head bolts are one example that are never going to be screwed in!) for some applications.
I don’t think I have ever seen a coach bolt/screw threaded completely to the head.
In summary, all is not simple when specifying a fixing. There are always going to be exceptions to the basic ‘rules’. Some bolts even have square heads, after all.🙂
|John Haine||27/08/2021 16:53:11|
|4188 forum posts|
Well, that's cleared that up then!
|larry phelan 1||27/08/2021 17:20:59|
|1095 forum posts|
Nothing in life is simple, is it ?
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.