Sites: GlobalSpec.com | GlobalSpec Electronics | CR4 | Electronics360
Login | Register
The Engineer's Place for News and Discussion®


Speaking of Precision

Speaking of Precision is a knowledge preservation and thought leadership blog covering the precision machining industry, its materials and services. With over 36 years of hands on experience in steelmaking, manufacturing, quality, and management, Miles Free (Milo) Director of Industry Research and Technology at PMPA helps answer "How?" "With what?" and occasionally "Really?"

Previous in Blog: The Only Must Read Book For You (And Your Organization) This Year   Next in Blog: 14 Causes of Machine Shop Pain
Close

Comments Format:






Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







13 comments

Distinguishing Bolts from Screws

Posted January 25, 2011 8:15 AM by Milo

Yes, bolts and screws are both externally-threaded fasteners. But how can you tell the difference?

Bolt - torque the nut

Bolt - externally threaded fastener that is

  • designed for insertion through holes in assembled parts
  • normally intended to be tightened (or released!) by torquing a nut

Screw - torque is applied through the head

Screw - externally threaded fastener that is capable of

  • being inserted into holes in assembled parts;
  • mating with a preformed internal thread, or forming its own thread;
  • being tightened or released by torquing the head.

A bolt is designed for assembly with a nut.

Nuts are required for bolts, optional for screws.

A screw has features in its design which makes it capable of being used in a tapped or preformed hole in the work. Because of basic design, it is possible to use certain types of screws in combination with a nut. Any externally threaded fastener which has the majority of the design characteristics which assist its proper use in a tapped or other preformed hole is a screw, regardless of how it is used in its service application.

Source: Distinguishing Bolts from Screws, US Department of Homeland Security, March 2006.

Bolt

Screw

Nut

Editor's Note: CR4 would like to thank Milo for sharing this blog entry, which originally appeared here.

Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Engineering Fields - Instrumentation Engineering - New Member

Join Date: Dec 2009
Location: San Antonio, TX USA
Posts: 856
Good Answers: 28
#1

Re: Distinguishing Bolts from Screws

01/25/2011 2:14 PM

Interesting, and quite correct. Maybe my question was answered in the editors note. I couldn't open the link but why in the world is the Department of Homeland Security interested in bolts and screws?

__________________
"Do not worry about your difficulties in Mathematics. I can assure you mine are still greater". - Albert Einstein
Register to Reply
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4898
Good Answers: 240
#2
In reply to #1

Re: Distinguishing Bolts from Screws

01/25/2011 2:22 PM

Homeland Security includes Customs.

Customs has to know if the "goods" are bolts or screws in order to apply proper duty, tariff, or exemption.

The publication is printed, i have a copy) as far as I can tell never made it online.

Milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Register to Reply
Power-User
United Kingdom - Member - New Member Engineering Fields - Transportation Engineering - New Member Technical Fields - Marketing/Advertising - New Member Hobbies - Target Shooting - New Member

Join Date: Sep 2007
Location: South coast of England
Posts: 373
Good Answers: 32
#8
In reply to #2

Re: Distinguishing Bolts from Screws

01/26/2011 4:26 AM

Why they need to differentiate between screws and bolts and have different tariffs beats me. It is interesting that they fiddle around with these minutiae when they don't even have logical categories for many classes of electronic equipment in the harmonised tariffs.

For instance a laptop (8471.30.00) does not come under Chapter 85 (electrical equipment). Instead it comes under:

CHAPTER 84 - NUCLEAR REACTORS, BOILERS, MACHINERY AND MECHANICAL APPLIANCES; PARTS THEREOF

71 Automatic data-processing machines and units thereof; magnetic or optical readers, machines for transcribing data onto data media in coded form and machines for processing such data, not elsewhere specified or included

.30 Portable automatic data-processing machines, weighing not more than 10 kg, consisting of at least a central processing unit, a keyboard and a display

Register to Reply Off Topic (Score 5)
Guru
Canada - Member - New Member

Join Date: Dec 2008
Location: Edmonton Alberta Canada
Posts: 631
Good Answers: 39
#9
In reply to #8

Re: Distinguishing Bolts from Screws

01/26/2011 2:30 PM

Computers are in chapter 84 because of their history. They are descended from the old lever crank adding machines which were originally not electrical.

In the 2005 rewrite of the tariff by the WCO (World Customs Organization) they finally moved monitors and printers out of the computer parts category and into the proper headings. The tariff is an ever changing organism but it is written and controlled by a huge bureaucracy and it takes years to make any meaningful changes. The electronics world is changing much faster than the WCO can move.

__________________
All that is required for evil to succeed is for good men to do nothing.
Register to Reply Off Topic (Score 4)
Guru
Hobbies - Automotive Performance - New Member Popular Science - Weaponology - New Member

Join Date: Oct 2008
Location: Want to be: 34° 34' 21.60" N, 92° 55' 42.28" W Really am in Arizona
Posts: 28321
Good Answers: 1068
#3

Re: Distinguishing Bolts from Screws

01/25/2011 6:12 PM

Whadda ya call them little pointy things ya screw into metal or wood?

__________________
In Search Of Intelligent Life, Somewhere; Anywhere.
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Ketchikan, AK, USA
Posts: 15260
Good Answers: 596
#4

Re: Distinguishing Bolts from Screws

01/25/2011 9:57 PM

Nobody ever says "Go bolt yourself!"

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Bangalore, India
Posts: 2669
Good Answers: 155
#5

Re: Distinguishing Bolts from Screws

01/25/2011 10:33 PM

Ahh, now i get it.

There was this news item about a lunatic escaping from the asylum, happened to catch a lone woman washing clothes at the river...the headline said "Nut screws washer and bolts"

__________________
Nothing worthwhile can ever be taught, it can only be learnt.
Register to Reply
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4898
Good Answers: 240
#7
In reply to #5

Re: Distinguishing Bolts from Screws

01/25/2011 11:30 PM

Milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Register to Reply
Power-User

Join Date: Feb 2009
Location: West Coxsackie, NY
Posts: 491
Good Answers: 8
#6

Re: Distinguishing Bolts from Screws

01/25/2011 11:29 PM

Screws utilize Screw drivers as Flat, Phillips, Square and star. All others require other than previously mentioned and host an array of different style heads to be used with different type tools, although the threads may also appear to be rolled in the form of what one would consider a wood type screw that is not quite right. So , half right/half wrong.

__________________
"Real Bass Players" do not use picks
Register to Reply
Guru

Join Date: Jul 2006
Location: "Dancing over the abyss."
Posts: 4898
Good Answers: 240
#11
In reply to #6

Re: Distinguishing Bolts from Screws

01/26/2011 2:56 PM

Not sure I understand what you are trying to say.

Milo

__________________
People say between two opposed opinions the truth lies in the middle. Not at all! Between them lies the problem, what is unseeable,eternally active life, contemplated in repose. Goethe
Register to Reply
Guru
Canada - Member - New Member

Join Date: Dec 2008
Location: Edmonton Alberta Canada
Posts: 631
Good Answers: 39
#10

Re: Distinguishing Bolts from Screws

01/26/2011 2:37 PM

I keep that publication near at hand. There is a revised edition that came out in 2010

__________________
All that is required for evil to succeed is for good men to do nothing.
Register to Reply
Guru

Join Date: Aug 2009
Location: Glen Mills, PA.
Posts: 2299
Good Answers: 109
#12

Re: Distinguishing Bolts from Screws

01/26/2011 8:56 PM

Screws are slang for prison warders in the UK.

__________________
Any action we take to protect liberty is itself, a threat to liberty.
Register to Reply Off Topic (Score 5)
Guru
Hobbies - CNC - New Member Popular Science - Biology - New Member Hobbies - Musician - New Member

Join Date: Dec 2008
Location: Canada
Posts: 2762
Good Answers: 128
#13

Re: Distinguishing Bolts from Screws

01/28/2011 3:43 PM

For any of us who complain of being screwed by the regulations, the company, the government, the ex-wife... there is now a clear way to determine whether you've been screwed, or in fact, bolted.

__________________
incus opella
Register to Reply
Register to Reply 13 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Copy to Clipboard

Users who posted comments:

Apothicus (2); artsmith (1); Chankley (1); Jimh77 (1); kvsridhar (1); lyn (1); Milo (3); passingtongreen (1); RDGRNR (1); Tornado (1)

Previous in Blog: The Only Must Read Book For You (And Your Organization) This Year   Next in Blog: 14 Causes of Machine Shop Pain
You might be interested in: Lead Screws and ACME Screws, Roller Screws, Ball Screw Repair Services