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Question for 'Limey' on 'Grub Screw'

dpasek

Aluminum
Joined
Jan 26, 2008
Location
Utah
I can't find the correct user name or the thread where this topic was mentioned.

The attached photo shows what looks to me to be pretty close to Limey's description of a grub screw, but I wanted to check since I never heard the term before.

The setscrews are standard cup point design. The setscrew in the collar at the left was loosened for disassembly so the collar could be moved. the screw point normally seats in the spotted hole to the lower right on the shaft. Does that fit the definition of a 'grub screw'?

There was a coupling sleeve on the keyed end of the shaft where it is slightly stained. One screw bit into the square key in the usual manner and the other engaged its point into the adjacent spotted hole. The entire assembly was quite secure and vibration resistant.

Thanks in advance for clarification
Dennis
 

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Grub screw = set screw.

Not over here it doesn`t.A grub screw is a headless screw which is threaded full length and will screw right through a tapped hole.Dennis`s pic shows them.
A set screw is a bolt that is threaded right up to the head.
Mark.
 
Ok, here is what it sounds like to me:

American <-> British
set screw <-> grub screw (headless, any style, full length thread)
cap screw <-> set screw (hex head, socket head, etc. full length thread)
bolt <-> bolt (as above but partial thread)
 
Grub Screw

A grub is the larvae of an insect which burrows into something- and disappears.
A grub screw is one which does exactly that!

A woodpecker is--- no, I'd better not!

A bark is -well, talk that one amongst yourselves!

Cheers

Norm- which is the mean-------and you can supply the rest-- and at my age, I need it
 
A grub screw is one that you would drill a tap drill into the juncture of a coupling to a shaft, tap it, and, in effect, key the shaft. This is lengthwise to the shaft.

I can't believe the Limeys here are ignorant of that, though I don't think they invented the term. Maybe they are young Limeys.

Cheers,

George
 
This is lengthwise to the shaft.

Don’t you mean a Scotch Key? Whilst it might use Grub screws as part of the assembly, the method is known as Scotch keying.

From the legend that Scot’s were frugal with money, and wouldn’t pay to have a key way machined.

I can't believe the Limeys here are ignorant of that
Have you been taking your grumpy pills again?

Phil.
 
Yes George,a grub screw can be used for keying a shaft,we also use it that way for keying bushes into bores when we bush something,also used as Dennis`s pic shows.But it is still a headless screw.
Nice to be suggested that I am young as I started my apprenticeship in the early sixties.

Mark.
 
Interesting. Looks like dpasek has got it straight. In my experience, the setscrews, or grub screws for you limeys, when used to secure a bushing or form a sort of key, were always called Dutchmans. Funny how we all use similar but different terms to describe things in the vernacular in the different english speaking countries. On a side note, I used to work with a Brit whose nickname was Limey. He was a master at darts.
 
Ditto on the "dutchman" designation.

That's what I've always heard those called. I think
it's a variation of "german" or deutch.

Jim
 
Bolt or Screw?

So when does a bolt become a screw or vice versa?

To say "a 2mm bolt" would be thought odd!

It seems to me that 6mm/1/4" is about the point of transition from "screw" to "bolt" but I wonder why.

I did my apprenticeship (nearly 50 years ago) in Australia with a firm that did heavy engineering; we used the term setbolt to describe a bolt threaded all-the-way. That meaning is not given in on-line dictionaries today although my Googling showed that the fully-threaded bolt that retains a vehicle crankshaft pulley is called a setbolt in automotive circles.

A similar device smaller than about 6 or 8mm would have been a setscrew.

And a grubscrew (setting aside the old joke) was & is a headless screw as Damien & others have described.
 
So when does a bolt become a screw or vice versa?

An explanation I read somewhere is that a bolt (hex heads) takes a nut and a screw (SHCS-socket head cap screw) goes in a tapped hole but that's not common usage. Around here, just about everything with a head is called a bolt and any headless screw is a set screw. The ones with a square head are square head set screws.

When I hear Dutchman, I think of a pressed in plug to allow the fixing of a machining error. Not sure where I got that though.
 
Let's not forget that what U.S. 'Murkin English first called a "setscrew" had a square head. In use, those setscrews showed a proclivity to snag just about anything that came close to them, which lead to the development of what was, at first, termed a "safety" setscrew that didn't protrude from the hub of the pulley / wheel / sheave or lathe dog.

British Commonwealth "grub screw" = obsolescent US "safety setscrew" = current US "headless setscrew"
 
Phil,

I religiously take my "grumpy pills". Scots have no comparison to a US executive when it comes to cutting costs. A Scot will cut costs till it becomes dangerous. A US exec will far surpass that. They will weigh the relative cost of lawsuit against financial benefit using the cheapest method they can. They can tie up a case in the courts till they have made so much that an adverse finding in court will seem like a drop in the bucket.

Mark,

I thought that what we were speaking of WERE what are called "setscrews", ie, straight threaded, headless, socketed, screws. Before modern materials, "setscrews" were "headed bolts", whether hex or square. I don't know when the Allen was invented.

Planner,

Why would you change nomenclature at a given dimension. A 2 mm capscrew would be the same as a 30 mm capscrew. It does have to be bolted and nutted to become a BOLT. A bolt, actually, was first defined as a plain shanked piece of some material that was used to halt movement. And then, 'bolts" are rolls of cloth and the like. Messy, don't you think?
We use "capscrew' and should be happy with that.

We have Allen head capscrews and we have hex head capscrews. OR, you can call anything over 1/4 a BOLT, anything under a screw.

Do as youwish.

Cheers,
George
 
Here is a definition of the difference between bolts and screws.
Bolt versus screw definition. The correct definition of bolt and screw is as follows. Bolts are headed fasteners having external threads that meet an exacting, uniform bolt thread specification (such as M, MJ, UN, UNR, and UNJ) such that they can accept a nontapered nut. Screws are headed, externally-threaded fasteners that do not meet the above definition of bolts.
This definition was lifted from this site. http://euler9.tripod.com/bolt-database/22.html
 
AFAIK a bolt has a nut, and a screw does not........

Cap screws being an example........ may be made to bolt specs...... add a nut and it's a bolt....

GRUB-screws are those little headless ones that when you drop one, make you GRUB around on the floor looking for the little ^%$#@.

probably originally got the name for the way they GRUB into the shaft, burring it up so it will NOT come out of the pulley without a hammer,........
 
Robin,

Thanks for the link. Where in that chart do you see the difference you refer to?

Looks to me as though "bolts" and "screws" have the same metallurgical requirements.
Thread and dimension have different "point" references, how much difference, I don't know, I looked at your link, am not going so far as to analyze your quibble.

In some cases, especially for you who do work for pay, you have to get the proper fasteners. Of course you would spec that when you order.

People here who do work for pay have asked about thread classes. They are worried about the work they are producing, whether it is meeting requirement.

Another definition of a "screw" is that it is fully threaded. A "bolt" is required, I think, to be threaded to 2 1/4 or 2 1/2 times the diameter.

Cheers,

George
 
This is an interesting thread (and the pun was not intentional)
When I started my apprenticeship in 1974, here in Oz, at the location I was at, the definition of bolt or screw was pretty easy. If you used a screwdriver to turn it it was a screw and if you used a spanner it was a bolt, Allen keys were classed as a spanner. Its interesting to see how the terminolgy for different things changes as we become more and more "globalised" and we have access to better and faster long distance communications.

bollie7
 








 
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