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View Full Version : What is the difference between a screw and bolt?


FlyingPete
9th of March 2005 (Wed), 14:04
Strange question for a photographic forum you might say, but I thought here is a group of smart people, they might just have an idea on this one.

I was cleaning out the garage on the weekend, and found my box of bits, nuts, bolts, screws nails etc. I decided this should be sorted, so I got a jar for each type including one for nuts and bolts and another for screws.

Here is where the fun begins, how do I tell if something is a bolt or screw, simple I thought, screws have sharp ends, bolts have flat ends. Well turns out I have a whole pile of little things I would call screws, but by the above definition are bolts.

So what is it? Any enlightenment from the masses?

Bishop Gideon
9th of March 2005 (Wed), 14:09
My feelings are the same... if it's pointy and made to make it's own how into something, it's a screw... if it needs a nut, or other such holding device, it's a bolt...

That's how I sort my stuff at home....

tommykjensen
9th of March 2005 (Wed), 14:09
scrolts ?

timmyquest
9th of March 2005 (Wed), 14:13
Can you use a screw driver for it?

when in doubt, grab the FBH...i'll refrain from the first letter, but the last two are Big Hammer

ajbalazic
9th of March 2005 (Wed), 14:30
From the Machinery's Handbook, 25th ed.:
"A bolt is an externally threaded fastener designed for insertion through holes...and is normally inteded to be tightened or released by torquing a nut. A screw is an externally threaded fastener capable of being inserted into holes... with a preformed internal thread or forming its own thread and of being tightened or realeased by torquing the head".

Personally, I like to screw. (sorry, I couldn't resist).

FlyingPete
9th of March 2005 (Wed), 14:33
Can you use a screw driver for it?

when in doubt, grab the FBH...i'll refrain from the first letter, but the last two are Big Hammer

That is a good start, if you can use a screw driver on it, it is a screw!

Although, I have some threaded metal things here that use a screw driver, have flat ends but screw into cage nuts? There is the first exception to that rule. So can you have nuts and screws as well???

BTW, I have one of those FBH's, I call it the 'adjustment' hammer :D I use it to 'fine tune' things!

FlyingPete
9th of March 2005 (Wed), 15:04
From the Machinery's Handbook, 25th ed.:
"A bolt is an externally threaded fastener designed for insertion through holes...and is normally inteded to be tightened or released by torquing a nut. A screw is an externally threaded fastener capable of being inserted into holes... with a preformed internal thread or forming its own thread and of being tightened or realeased by torquing the head".

So a bolt aways has a nut, where a screw does not, can't think of any exceptions to that yet!

Personally, I like to screw. (sorry, I couldn't resist).

I was wating for that one to com up :eek:

CoolToolGuy
9th of March 2005 (Wed), 15:13
So a bolt aways has a nut, where a screw does not, can't think of any exceptions to that yet!


Here in the USA we have things known as lag bolts which have a piercing (non machine thread) thread and are used to screw into lumber framing or concrete blocks, so that would be an exception.

Generally, bolts have a head that must be 'wrenched' with a hex or square wrench or spanner. If they have machine threads and require an Allen (inhex) or other drive tool that inserts into the head they are usually known as 'cap screws'.

Hope this helps.

Have Fun,

FlyingPete
9th of March 2005 (Wed), 15:41
Here in the USA we have things known as lag bolts which have a piercing (non machine thread) thread and are used to screw into lumber framing or concrete blocks, so that would be an exception.

Interesting, they are generally refered to as self tapping wood screws (wood screws having a steeper larger thread than machine) down here, they have a almost a blade setup on the ends of some to get them started.

[QUOTE=CoolToolGuy]Generally, bolts have a head that must be 'wrenched' with a hex or square wrench or spanner. If they have machine threads and require an Allen (inhex) or other drive tool that inserts into the head they are usually known as 'cap screws'.
[QUOTE]

Hmmm need a third jarr, I have pleantly of those!

CyberDyneSystems
9th of March 2005 (Wed), 15:42
Self tapping wood screws are very differnt from a lag... lags actually get used with anchors in concrete as often as not,. but there threads are such that they can be used in wood as well.

http://www.go2marine.com/go2_structure/5/3/1/1/53118F-p.jpg
LAG BOLT

http://flowerframers.com/images/Illustrations/lag_bolt.jpg
LAG and ANCHOR/SHEILD

Tom W
9th of March 2005 (Wed), 15:45
Personally, I like to screw. (sorry, I couldn't resist).

But if the wrong person shows up, you'd better bolt. :)

Tom W
9th of March 2005 (Wed), 15:47
If they have machine threads and require an Allen (inhex) or other drive tool that inserts into the head they are usually known as 'cap screws'.

Hope this helps.

Have Fun,

I must add that "allen" wrenches are not named after Tooltime Tim Allen. :)

CyberDyneSystems
9th of March 2005 (Wed), 15:48
Generally, bolts have a head that must be 'wrenched' with a hex or square wrench or spanner. If they have machine threads and require an Allen (inhex) or other drive tool that inserts into the head they are usually known as 'cap screws'.


I'd never given any of it any thought before,. other than to assume the terms were interchangeable,. with certain affectations towards Screws being self tapping and bolts using nuts...

But I think CTG is onto something as I can't think of any exceptions?

CyberDyneSystems
9th of March 2005 (Wed), 15:50
I must add that "allen" wrenches are not named after Tooltime Tim Allen. :)

Allen was a close personall friend of Robertson and Phillips.. they all tended to avoid poor old Lester Flat... ;)

Tom W
9th of March 2005 (Wed), 15:51
Allen was a close personall friend of Robertson and Phillips.. they all tended to avoid poor old Lester Flat... ;)

A hex on you! :D

CoolToolGuy
9th of March 2005 (Wed), 15:52
Then there's that fellow Torx . . .

Have Fun,

CoolToolGuy
9th of March 2005 (Wed), 15:54
. . . and, of course, the singer Michael Bolton. :lol: :lol: :lol:

Tom W
9th of March 2005 (Wed), 16:09
. . . and, of course, the singer Michael Bolton. :lol: :lol: :lol:

I believe, like Chrysler's 1960's lug nuts, his threads might be reversed from the typical.

FlyingPete
9th of March 2005 (Wed), 16:17
Well there you go, this thread is now screwed! :lol:

Heaps of good info though!

CoolToolGuy
9th of March 2005 (Wed), 16:22
Yes, by now its not worth a Whit! :lol: :lol: :lol: (for those that are totally obsessed with vintage British machinery).

Have Fun,

Avalonthas
9th of March 2005 (Wed), 16:23
Bolts are half flat and half threaded, whereas screws are fully threaded. Bolts require some sort of nut to keep it tight, where a screw can be used on its own. A bolt is used when you need something to be really strong, as its harder to rip out a bolt then it is a screw. Screws dont have to be pointy, they just have to have thread going all the way down to the tip from the head.

CoolToolGuy
9th of March 2005 (Wed), 16:25
Bolts are half flat and half threaded, whereas screws are fully threaded. Bolts require some sort of nut to keep it tight, where a screw can be used on its own. A bolt is used when you need something to be really strong, as its harder to rip out a bolt then it is a screw. Screws dont have to be pointy, they just have to have thread going all the way down to the tip from the head.

I don't know, I see plenty of wood screws that have a plain shoulder at the top . . .

Have Fun,

CyberDyneSystems
9th of March 2005 (Wed), 16:27
Bolts are half flat and half threaded, whereas screws are fully threaded. Bolts require some sort of nut to keep it tight, where a screw can be used on its own. A bolt is used when you need something to be really strong, as its harder to rip out a bolt then it is a screw. Screws dont have to be pointy, they just have to have thread going all the way down to the tip from the head.

Your just making this up as you go along! :lol:

Still,... nice to see this thread is back on course

CoolToolGuy
9th of March 2005 (Wed), 16:38
Your just making this up as you go along! :lol:

Still,... nice to see this thread is back on course

CDS, I had a feeling you would tap into this one before we let it die.

Have Fun,

Persian-Rice
9th of March 2005 (Wed), 16:55
I'm not an expert, but work on race cars regulalrly and have met many experts.

The difference is that screw is used to be screwed into a female socket(can also be a nut, but very rare) it can be either pre tapped or not tapped(the screw threads itself). The head nor the size have anything to do with it.

A bolt is to be used in conjunction with a nut, period.

Its not that complicated, just the people dont really care to learn about it. If it doesnt have a nut, then it isnt a bolt. People have used wrong terminology for a long time, and it has stuck to certain degree. Kleenex is a brand, but most people call all facial tissue paper Kleenex.

CoolToolGuy
9th of March 2005 (Wed), 16:59
I'm not an expert, but work on race cars regulalrly and have met many experts.

The difference is that screw is used to be screwed into a female socket(can also be a nut, but very rare) it can be either pre tapped or not tapped(the screw threads itself). The head nor the size have anything to do with it.

A bolt is to be used in conjunction with a nut, period.

Its not that complicated, just the people dont really care to learn about it. If it doesnt have a nut, then it isnt a bolt. People have used wrong terminology for a long time, and it has stuck to certain degree. Kleenex is a brand, but most people call all facial tissue paper Kleenex.

I beg to differ:

See lag bolt, above.
Most engines (even the ones on race cars) have Head Bolts that thread into the block, not a nut.
Have Fun,

CyberDyneSystems
9th of March 2005 (Wed), 17:33
I'm telling,. there's a reason he's called "tool guy" and it ain't because he's Tim Allen! ;)

Rick has this subject locked tite

CoolToolGuy
9th of March 2005 (Wed), 17:37
I'm telling,. there's a reason he's called "tool guy" and it ain't because he's Tim Allen! ;)

Rick has this subject locked tite

Yea, but I'm not a Mod, so I'm not a threadlocker like you are! (only when you need to be) ;) :lol: :lol:

Have Fun,

tim
9th of March 2005 (Wed), 17:59
If you do it up with a screwdriver, it's a screw. If you do it up with a spanner or similar, it's a bolt.

FlyingPete
9th of March 2005 (Wed), 18:09
If you do it up with a screwdriver, it's a screw. If you do it up with a spanner or similar, it's a bolt.

I've got some nuts and bolts right here where the bolt has a round head, and requries a screw driver!

I'm with the if it is used with a nut, its a bolt, otherwise a screw theory so far.

http://www.etl.co.nz/images/main/200005.jpg
Here is the above mentioned M6 Cage Nut and M6 x 12 Bolt. I have actually seen these refered to as screws, but there is a nut involved!

CyberDyneSystems
9th of March 2005 (Wed), 18:31
Rick,. I just recalled the exception to your theory...

"Stove Bolt" .. takes a screwdriver to install.

http://www.milspecfasteners.com/reference/images/bolts/stove_bolt.gif
STOVE BOLT

CyberDyneSystems
9th of March 2005 (Wed), 18:35
Here's a a few pages that give the illustrations that proves that none of our theories are correct,. and there is no consistancy,..

http://www.hssales.com/product_specifications.htm

http://www.jamestowndistributors.com/ak/Fasteners/Screws_Bolts/index.html

Tom W
9th of March 2005 (Wed), 19:02
And then there's the Carriage bolt. No tools to tighten this one.

http://www.mmsacc-stainless.com/assets/auto_generated_images/carriage.gif

Tom W
9th of March 2005 (Wed), 19:06
Except for CDS's stove bolt, it seems that screws are "innies" and bolts are "outies" or "flatties".

jimsolt
9th of March 2005 (Wed), 19:15
Most people don't want a cigarette after a good bolt.

Jim

Conk
9th of March 2005 (Wed), 20:33
Oh man! I can't believe all these replies never answered the mans question. In layman's terms anyway.
We all know screws have the point. Ok. Bolts usually have threads that will accept a nut of the same size. This we also know. However, most "bolts do have a shank that is threadless. Normally if a bolt has full threads then it can be referred to as a "machine screw". Unless of course the head is round and somewhat flat then you can call that a carriage bolt. Bolts usually have a hex head on them with identifying marks that I.D. their grade. Machine screws do not. Machine screws usually come with the type of head that an ordinary screw does, pan, oval, or flat which all three types can accommodate a slot, Phillips (goofy american design) :confused: , robertson superior Canadian design) :cool: , hex, torx, and security.

Anyway, I couldn't resist replying to this thread. I just happened to be a marine mechanic.

CoolToolGuy
9th of March 2005 (Wed), 21:25
I've got some nuts and bolts right here where the bolt has a round head, and requries a screw driver!

I'm with the if it is used with a nut, its a bolt, otherwise a screw theory so far.

http://www.etl.co.nz/images/main/200005.jpg
Here is the above mentioned M6 Cage Nut and M6 x 12 Bolt. I have actually seen these refered to as screws, but there is a nut involved!

These are known as fillister-head screws, they may also be called cheese-head screws.


I don't think there is a hard and fast rule for these things. As CDS points out, a stove bolt has a slot for a screwdriver, and it might be a bolt because it was meant to 'bolt' two sheets of steel together. But to say that a bolt must have a nut, else it is a screw is just screwy.

Back to the original issue - I would sort the machine thread fasteners separately from the wood screw thread fasteners and possibly, those separate from the sheet metal thread fasteners.

Have Fun,

Conk
10th of March 2005 (Thu), 00:23
Aww, now your getting into the specialty stuff. :lol:

cmM
10th of March 2005 (Thu), 00:51
how did I miss this thread? :-P
Did I mention I design screws for a living ? I'm a CAD engineer for a fastener manufacturer.

No all screws are sharp pointed/self tapping, and not all bolts are wrenched. From a consumer's standpoint, the only difference is application, and generally size. Other than that, heads (hex, round,flat, etc....) and/or recesses (phillips, torx,square,sloted, etc...) can be found in either.
From a manufacturing standpoint, there is a bigger difference between the 2, but that's kinda irrelevant...

Moppie
10th of March 2005 (Thu), 01:00
Don't you bolt after a screw?


Iv been working in engineering related fields since I was 15, and I have no idea what the differnce is.
At the most basic level I would say a bolt needs to be put through a pre drilled hole in to a captive thead, e.g. a nut.
While a screw creates its own hole and captive thread.

Anything else, e..g a cap screw or a stove bolt, is something differnt. Either a variation of a scew or a bolt, or a combination of the two.

cmM
10th of March 2005 (Thu), 01:05
Don't you bolt after a screw?


Iv been working in engineering related fields since I was 15, and I have no idea what the differnce is.
At the most basic level I would say a bolt needs to be put through a pre drilled hole in to a captive thead, e.g. a nut.
While a screw creates its own hole and captive thread.

Anything else, e..g a cap screw or a stove bolt, is something differnt. Either a variation of a scew or a bolt, or a combination of the two.

No, not all screws are "tapping screws", they don't create their own holes.

The basic and most important classification is by application: tapping screws, machine screws, wood screws, rivets, bolts, studs, and so on.
Then there are other classifications based on characteristics like heads, thread types, and so on.

Moppie
10th of March 2005 (Thu), 01:52
No, not all screws are "tapping screws", they don't create their own holes.

No, but they create thier own thread in the hole :)
At the most basic level of course.

Obviously a cap screw requires a pre taped hole to be tighten into, either nut, or hole in plate etc. But then its not a screw its a Cap screw

Big_B
10th of March 2005 (Thu), 04:26
Screw - making a mistake

Bolt - what you do before anyone finds out.

chris.bailey
10th of March 2005 (Thu), 07:57
Screw - making a mistake

Bolt - what you do before anyone finds out.

Superb. Thats the best definition so far :-)

cmM
10th of March 2005 (Thu), 08:44
No, but they create thier own thread in the hole :)
At the most basic level of course.

Obviously a cap screw requires a pre taped hole to be tighten into, either nut, or hole in plate etc. But then its not a screw its a Cap screw
wrong.
Take machine screws for example. How about set screws?

Big_B, that's awesome! :D

CoolToolGuy
10th of March 2005 (Thu), 09:58
Tradition plays a part in this as well - earlier in this thread I mentioned Head Bolts for automotive engines, and that term has stuck. But many current-day engines use fasteners that require a splined tool like a Torx or Allen wrench to tighten them, technically making them Cap Screws - and some also are tightened in a fashion where they stretch, they are known as stretch bolts.

Not cut and dried. . .

Take this tradition thing to another, very much more traditional, venue - Golf.

Most Players have an assortment of Woods and Irons in their bag. But, even though there is a resurgence of Persimmon clubs available from makers like Louisville Golf, I would say that in over 95% of the bags you will see today those clubs are Titanium, Stainless Steel, Aluminum (Aluminium for the Brits), or composite material. And the clubs known as Irons are not iron anymore either. They are also Titanium, Steel, or Stainless Steel. But somehow the names stick.

My 2 OT cents worth.

Have Fun,

samdring
10th of March 2005 (Thu), 12:49
Your surprise definition of a screw was a veritable bolt

FlyingPete
10th of March 2005 (Thu), 16:50
My wife read this thread last night, when I asked her this morning if she had seen some bolts lying around I needed this morning, she challenged me on that fact ans said she had seen some screws, but no bolts!

I suppose the treaded shafts or hardened steel mentioned could go either way depending on which of the 101 definitions in this thread I used!

As for my jars, I am going to solve the sorting issue by having more jars for all those wierd threaded shafts of steel (brass and alloy as well) that I have. I will put these in a box called 'Fastenings'.

Moppie
10th of March 2005 (Thu), 21:15
wrong.
Take machine screws for example. How about set screws?



They are Set Screws and Machine Scews.
They are not Screws.

i.e, they are a subset of fastners, not a subset of screws, or bolts.

The Set "fastners" would include {bolts, screws, cap screws, strech bolts, etc etc}
The subset of fastners, "screws" would include {philips head, flat head, self tapping etc}
The subset of fastners, "bolts" would include {10mm, 1/2inch, 13mm, fine thread, course thread, galvanised etc etc}
The subset of fastners, "Cap screws" would include {10mm, 1/2inch, 13mm, fine thread etc etc}

etc etc.

wintermute76
10th of March 2005 (Thu), 22:15
As a general rule a bolt uses a nut, and has an unthreaded portion where it sits in the material. Bolts AFAIK are also 1/4" or larger.

But like everything, there are exceptions :D

Here's some more definitions from http://www.boltscience.com/pages/glossary.htm

SCREW A headed threaded fastener that is designed to be used in conjunction with a pre formed internal thread or alternatively forming its own thread. Historically, it was a threaded fastener with the thread running up to the head of the fastener that has no plain shank. However this definition has largely been superseded to avoid confusion over the difference between a bolt and a screw. BOLT A bolt is the term used for a threaded fastener, with a head, designed to be used in conjunction with a nut.

cmM
10th of March 2005 (Thu), 22:51
Moppie, what you speak of are classifications by physical charateristics (size,head type, recess type, thread type, plating/coating), and these classifications are shared between most types of fasteners, for example: a set screw can have different types of recesses, just like a tapping screw or a bolt.

This is how fasteners are classified in the Inch Fastener Standards (published by IFI Industrial Fasteners Institute) which are the standards for the entire Fastener Industry in the US and beyond.

First and most important, as I said, is the type of screw which is most often defined by its application (bolts, studs, screws, nuts, socket screws, tapping screws, machine screws, rivets, washers and pins,taptite, plastite, tri-plask, duo-taptite, and a few more...)
Then each of these are further classified by 2 categories usually: type of thread, and heads. Now a lof of types of screws only have one type of thread, but there are sometimes variations. For example, tapping screws can have a whole whack of different thread types.
Parallel to the thread type classification is a classification by head type(pan, flat, fillister, hex,truss, etc...).
Further more, for each head type there's a classification by recess type for each of those heads (square, slot, phillips, torx, hex,etc..)
And lastly, each of these are categorized by size.
Other properties like materials/plating/coating don't have a very well defined classification because it's mostly dependent on customer prefferences.

And back to the original question, the only difference between bolts and screws is application, and usually size, that's it.

Conk
10th of March 2005 (Thu), 23:03
how did I miss this thread? :-P
Did I mention I design screws for a living ? I'm a CAD engineer for a fastener manufacturer.

Well, that just about solves everything. :lol:

Big_B
11th of March 2005 (Fri), 02:28
Superb. Thats the best definition so far :-)

He he! Cheers :D

Moppie
11th of March 2005 (Fri), 04:28
First and most important, as I said, is the type of screw which is most often defined by its application .............................
.


I think you just redifined what I said into engineering speak :)


I like your sig by the way :cool:

roanjohn
11th of March 2005 (Fri), 14:32
You guys are all NUTS!!! Totally SCREWED my mind reading all these terminology!!! :lol: :lol: :lol: :lol: :lol:

Ro1

RickHulshof
11th of March 2005 (Fri), 18:30
MHO - Anything 1/4 -20 or bigger is a bolt

The Braun
13th of March 2005 (Sun), 18:02
it doesnt matter if you know it is a bolt or a screw it is

gcl01
2nd of September 2010 (Thu), 22:28
A screw has a thin spacer like a washer under the head (you rotate a screw, hold a bolt rigid and turn the nut). A screw has a shank, between the threads and the head, with a diameter no larger than the major diameter of the thread. A screw has a head height slightly less than a bolt. A bolt has a shank diameter, between the threads and the head, LARGER than than the major diameter of the thread. A bolt has no "washer" type surface under the head and has a looser tolerance (very slightly lower hex size allowed) for the hex size than a screw. For more information look in the ANSI/ASME standard A18.2 or A18.3. The Industrial Fastener Institute manual has Metric and SAE thread books with all the specifications for threads and fasteners of all type. Bossard also has an on-line manual with specifications for Metric fasteners.

FlyingPete
2nd of September 2010 (Thu), 22:39
A screw has a thin spacer like a washer under the head (you rotate a screw, hold a bolt rigid and turn the nut). A screw has a shank, between the threads and the head, with a diameter no larger than the major diameter of the thread. A screw has a head height slightly less than a bolt. A bolt has a shank diameter, between the threads and the head, LARGER than than the major diameter of the thread. A bolt has no "washer" type surface under the head and has a looser tolerance (very slightly lower hex size allowed) for the hex size than a screw. For more information look in the ANSI/ASME standard A18.2 or A18.3. The Industrial Fastener Institute manual has Metric and SAE thread books with all the specifications for threads and fasteners of all type. Bossard also has an on-line manual with specifications for Metric fasteners.

Thanks for that description! Amazing best reply took only 5 years!

KCY
3rd of September 2010 (Fri), 00:04
Thanks for that description! Amazing best reply took only 5 years!

:lol: finally you can finish sorting out garage :p

FlyingPete
3rd of September 2010 (Fri), 02:26
:lol: finally you can finish sorting out garage :p

Oh well I think I chucked that stuff all out when we moved two years ago :rolleyes:

Woolburr
3rd of September 2010 (Fri), 02:33
You're screwed now!

FlyingPete
3rd of September 2010 (Fri), 02:36
You're screwed now!

Yep because I bolted!

Woolburr
3rd of September 2010 (Fri), 02:52
Hope this taught you a valuable lesson...:lol::lol::lol::lol::lol:

preveen
3rd of September 2010 (Fri), 03:03
Wasn't it Confucius who initially explained the difference?

It takes many bolts to build a crib, but only one screw to fill it?

Or was it nails to build a crib?

FlyingPhotog
3rd of September 2010 (Fri), 03:07
Ok, who made this thread sit bolt upright from the dead?

KCY
3rd of September 2010 (Fri), 03:08
Ok, who made this thread sit bolt upright from the dead?

I don't know but whoever did it must have a screw loose :p

Woolburr
3rd of September 2010 (Fri), 03:12
Amazingly, it wasn't Mark this time!

neilwood32
3rd of September 2010 (Fri), 11:09
Someone screwed up major style letting this one come back!

tonylong
3rd of September 2010 (Fri), 11:17
Someone screwed up major style letting this one come back!

I'd say once he realized his screw-up, he probably bolted for the exit...

KCY
3rd of September 2010 (Fri), 13:25
I think you guys have taken it way over the top, quit screwing around

thomascanty
3rd of September 2010 (Fri), 17:55
Wow! Someone went through all the trouble to register on the site just to answer a question on a thread that's been dormant for five years?!? That's hilarious! :lol:

FlyingPete
3rd of September 2010 (Fri), 19:16
Yeah I thought this thread was nailed.

birdfromboat
3rd of September 2010 (Fri), 20:59
I went to school to learn this stuff, and you know what? I just don't care anymore.
screws, bolts, nuts, lags, it all just runs together......there is a differance between a machine screw and a screw machine, you cant make a bolt by cutting a thread on a lathe unless it has a lead screw. Most of the time if I am asking for a specific fastener, I don't use the word bolt or screw or lag, just the screw thread nomenclature, the length and the head style as in a 1 inch #8 self tapper phillips head or a 1 and a half inch hex head 1/4-20 and so on.
That hole in the bottom of your camera has 1/4-20 screw threads in it, but you better use a bolt if you plan to use it to hold your camera.

Any one else out there ever heard the tale of corkscrew Rick?
I won't tell it here, it is a rather colorful story used to train machinist apprentices about the awful possibilities caused by not specifying size and type and pitch of thread. Use your imagination.

doctordare
10th of September 2010 (Fri), 00:44
A riddle for you home handymen...

What do you call a drink made out of vodka, orange juice, and Milk of Magnesia?

A Phillips Screwdriver!

(Sorry, one of my favorites from my dad.)

trailguy
15th of September 2010 (Wed), 12:47
A screw has a relatively pointed tip, and some are self-tapping.
That's why it's not called bolt.