Welcome Naveed1114 - Learn the Difference Between Screws & Bolts

In summary, the conversation discusses the differences between screws and bolts. There is no clear distinction between the two, but generally, screws have tapered bodies and are used for materials like wood or sheet metal, while bolts have cylindrical bodies and are used with nuts or tapped holes. The terms "cap screw" and "lag bolt" can be confusing as they refer to different types of screws and bolts. The size of the fastener can also be a differentiating factor, with larger sizes being considered bolts. Other types of screws include set screws and machine screws, which have different head styles. The term "peanut" is also mentioned as a type of screw head. The conversation also mentions that the term "screw" is derived from the type
  • #1
NAVED EJAZ
4
0
HELLO EVERYBODY
I AM A NEW MEMBER .WELCOME ME BY HELPING ME IN

DIFFERENCIATING BETWEEN SCREWS AND BOLTS

THANKS AND REGARDS
NAVEED1114@HOTMAIL.COM
 
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  • #2
Welcome to PF, Naved.
I'm not sure if there's a distinct line between the two as far as official designations goes. The real engineers probably know.
To me, generally, a screw involves a tapered body that is intended to 'auger' into something like wood or sheet metal. A bolt has a cylindrical body with constant threads that are meant to engage a matching set of female threads in a nut or tapped hole.
Where it gets confusing for me is that a 'cap screw' is actually an Allen-head bolt, and a 'lag-bolt' is a hex-head screw. :confused: It almost implies that if you use a screwdriver on it, it's a screw, and if you use a wrench, it's a bolt... but that can't be right.
 
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  • #3
The biggest difference that I have noticed is that screws come to a sharp point, while bolts tend to have a blunt end. Also, screws tend to be used in situations where there is no hole, or simply a pilot hole, while bolts are used with a complete hole, and use a nut or other threaded reciever on the other end to secure the whole arrangement.:wink:
 
  • #4
A cap screw does not have a point, nor is it necessarily used with a nut!

I don't think there's a clear-cut difference; I liked Danger's idea of a screw being applied with a screwdriver, but again you'd do up a cap screw with an allen key or socket... And a screw doesn't necessarily cut its own thread either.

Ultimately, I'd say a bolt's threads engage in a nut, where a screw's threads engage within the workpiece itself (either in pre-formed threads, or threads tapped by the screw itself).
 
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  • #5
I think that's a good definition. makes a lot of sense...
 
  • #6
Agreed. When posting my answer, I totally forgot about the terms 'set screw' and 'machine screw', both of which would be bolts by the definition that I came up with. Brewskie's is a lot more self-consistent. :cool:
 
  • #7
In my mind the main differentiation would be size. Anything over about [itex] \frac 3 8 [/itex]" or maybe 1cm is a bolt, smaller is a screw. A taper implies a wood screw or a self tapping sheet metal screw. Machine screws have no taper and come in a wide variety of head styles. Cap screw, button head, flat head, fillister head then you can have within each head style, slotted, phillips, Robertson (Square) and hex heads. To get an education in screws and bolts get your hands on a Machinery Handbook.
 
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  • #8
Again, this makes a lot of sense to me. You learn something new every day. I'm learning something new here!:biggrin:
 
  • #9
Integral said:
Cap screw, button head, flat head, fillister head then you can have within each head style, slotted, phillips, Robertson (Square) and hex heads.
How dare you leave out my favourite, the 'peanut'? :grumpy:
 
  • #10
I've always thought of a "screw" as something I would turn with a philips head or flat head screwdriver, and a "bolt" as something I would turn with a wrench or a socket-driver

carp
PropulsionAccess.com
 
  • #11
From what is published, the term "screw" seems to have been shortened from the type of threads that are used on bolts (screw threads). Joints and such are "bolted" together. However bolts have threads, screw threads. The term "screw" is simply a derivation of a bolt with screw threads. Most US bolts have Unified Standard screw threads that follow that spec.
 
  • #12
Thanks Everybody For Your Valuable Views

I Could Not See "mech Handbook"due To Unavailability.but Could See Encarta.

What Could I Understand Is

All The Cones And Cylinders Having Screw Threads Are Screws.however The Screws Used With Machines Are Called Machine Screws Or "bolts".the Threads Of Bolts Are Matched By The Threads On The Inside Of A Nut

Moreover---marine Propellers Are Also Termed As Screws And Aircraft Propellers Are Termed As Airscrews.--the Propeller Is Essentially A Screwthat,when Turned, Pulls Itself Through The Air Or Water In The Same Way That A Bolt Pulls Itself Through A Nut.--typical Propellers Consists Of Two ,three,four Blades ,each Of Which Is A Section Of A Helix,which Is The Geometric Form Of A Screw Thread.

Thanks And Regards
 
  • #13
Screws And Bolts

Is It So??
 

1. What is the difference between a screw and a bolt?

A screw is a fastener with threads that are designed to be screwed into a material and hold it in place. A bolt, on the other hand, has threads on one end and a smooth shank on the other, and is usually used with a nut to hold materials together.

2. How do I determine if I need a screw or a bolt for my project?

This depends on the specific application and the materials being used. Generally, screws are used for lighter duty applications and bolts are used for heavier duty applications. It's important to consider the weight and strength requirements of your project when choosing between a screw and a bolt.

3. Can screws and bolts be used interchangeably?

In some cases, screws and bolts can be used interchangeably, but it's not always recommended. Bolts are usually stronger and more durable than screws, so using a bolt in place of a screw may provide better support and stability. However, using a screw in place of a bolt may not provide enough strength to hold materials together properly.

4. What are the different types of screws and bolts?

There is a wide variety of screws and bolts available, each with their own unique features and purposes. Some common types of screws include wood screws, machine screws, and sheet metal screws. Common types of bolts include hex bolts, carriage bolts, and eye bolts.

5. How do I choose the right size screw or bolt for my project?

To choose the right size screw or bolt, you need to consider the diameter, length, and thread count. The diameter of the screw or bolt should match the size of the hole it will be inserted into. The length can vary depending on the thickness of the materials being joined. Thread count refers to the number of threads per inch and should be chosen based on the weight and strength requirements of the project.

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