Screw vs Bolt

[bob58o]

Is the only difference between a screw and a bolt is that a bolt is used with a nut? I never know what to call these things.

 

[Whitetrashrocker]

A screw usually is coarse thread, and uses the material to hold its self in.
A bolt goes threw the material and held with a nut.

But not always. Like a cover bolt. Goes threw the cover into a threaded hole in the block.

But now in slang terms one is a crewd term and the other is the action that follows. Hehe.

 

[ezcome-ezgo]

A screw is an inclined plane wrapped around a nail. Where a fastener forms its own thread in the component being fastened, it is called a screw.

A bolt is a form of threaded fastener with an external male thread. Bolts are for the assembly of two unthreaded components, with the aid of a nut.

Also I got screwed, so I had to bolt.

 

[anickode]

A screw engages with wither the material being fastened, or the material being fastened to, ie wood, sheet metal, a pre-threaded hole, etc.

A bolt engages with a nut on the opposite side of the material.

That's all.

A single fastener can be a screw or a bolt depending on how it is installed. A 3/4"-10 fastener for example is a hex cap screw if it's threaded into a tapped hole, and a hex bolt if installed with a nut on the back.

Easy way to remember:
If you have to screw it in, it's a screw.

 

[bob58o]

A screw engages with wither the material being fastened, or the material being fastened to, ie wood, sheet metal, a pre-threaded hole, etc.

A bolt engages with a nut on the opposite side of the material.

That's all.

A single fastener can be a screw or a bolt depending on how it is installed. A 3/4"-10 fastener for example is a hex cap screw if it's threaded into a tapped hole, and a hex bolt if installed with a nut on the back.

Easy way to remember:
If you have to screw it in, it's a screw.

This is my understanding, even if I don't use the correct term most of the time.

Go figure. Screwing and Bolting all boils down to the nut. LOL

---------- Post added at 11:05 AM ---------- Previous post was at 10:59 AM ----------

So really, these small engines have side cover screws, valve cover screws, head screws,....
Bolts is an incorrect term????

 

[ezcome-ezgo]

No, because the fastener is not making the thread. The thread is machined, and is therefore, in principle, a nut. Like you.

 

[bob58o]

No, because the fastener is not making the thread. The thread is machined, and is therefore, in principle, a nut. Like you.

Hmmm, I don't think that a screw has to cut the threads. I think you made this up Mr. McBean.

Gasoline anyone?
https://www.youtube.com/watch?v=xi07r99qMGA

 

[ezcome-ezgo]

If the argument is that the fastener being used, for example, on your side cover is a screw, because there is no nut present, then if you take that exact same "screw" and fasten it elsewhere using a nut, it has now transmorgiphied into a bolt?

 

[bob58o]

Well my side cover and and head have studs....

But I guess my argument is that a bolt has to extend through the material and used with a nut. Meaning through holes, not threaded.

So yes I'm saying that if the same fastener was used in a tapped hole application and then is switched to a through hole application with a nut, then it has morphed from a screw to a bolt.

Screws –are threaded in such a way that they fasten themselves within the material and do not require a nut to be tightened.

Bolts – are threaded to allow a nut to be fastened to the end opposite the head. To do this a bolt must pass through the items it is fastening together. - the internet 2018

 

[itsid]

That's NOT what I learned of being the difference..

SCREWS are ALL thread (even machine screws) [some cut their own threads some use a threaded hole..stills screws]
BOLTS however have an unthreaded part (and indeed are used with NUTS)

That's what I've been told... but I guess that's the old
"while there are flathead screws, there is no such thing as a flathead screwdriver!"
dilemma.

basically a bolt holds one adjustable part to a fixed part,
whereas a screw fastens two parts in a rotationally locked manner (ideally).

As long as people know what you are talking about, you can call them anything you want;
(pastell for example is STRICTLY blue color! pastell colors however come in many different dull shades; they're just named incorrectly still everybody knows what's meant by that)

And yes, I call all machine screws bolts myself,
just because that's common in your language (as far as I can tell),

'sid

PS Ohhh look.. wikipedia to the rescue:
https://en.wikipedia.org/wiki/Bolt_(fastener)
https://en.wikipedia.org/wiki/Screw#Differentiation_between_bolt_and_screw

 

[anickode]

If the argument is that the fastener being used, for example, on your side cover is a screw, because there is no bolt present, then if you take that exact same "screw" and fasten it elsewhere using a nut, it has now transmorgiphied into a bolt?

Yes.

 

[bob58o]

That's NOT what I learned of being the difference..

SCREWS are ALL thread (even machine screws)
BOLTS however have an unthreaded part

That's what I've been told... but I guess that's the old
"while there are flathead screws, there is no such thing as a flathead screwdriver!"
dilemma.

As long as people know what you are talking about, you can call them anything you want;
(pastell for example is STRICTLY blue color! pastell colors however come in many different dull shades; they're just named incorrectly still everybody knows what's meant by that)

'sid

In my brief research (like 10 minutes), I found that some confusion stems from old times when a bolt was just a rod (with no threads) through material connected with a pin or something on the other end.

So I follow what you are saying.

Also found out that there is not really a universal used way to determine the difference.
Growing up, I always believed screws had a pointed tip. Wood screws, self tapping sheet metal screws,... I no longer think that is true.

Where's Pat when you need him?

 

[itsid]

LOL.. Yepp...
and then you stumble across a lag bolt and all goes haywire



'sid

 

[anickode]

LOL.. Yepp...
and then you stumble across a lag bolt and all goes haywire

View attachment 95811

'sid

That's technically a lag screw, though it is commonly referred to as a lag bolt.

Look them up from any major fastener and hardware supplier like Grainger, Fastenal, etc (not home Depot)... They will be categorized as "hex head lag screws"

 

[itsid]

That's technically a lag screw, though it is commonly referred to as a lag bolt.

Look them up from any major fastener and hardware supplier like Grainger, Fastenal, etc (not home Depot)... They will be categorized as "hex head lag screws"

Well the manufacturer calls it a lag bolt...
fastenal lists lag screws.. ALL threaded (no smooth shaft)
here's one of them:

and I couldn't find one with a smooth shaft...(although I admit I only browsed through two of the pages of results)



KD fasteners (random example of a MANUFACTURER website)
has this page to offer:
https://www.kdfasteners.com/lag-bolts.html

So yeah, I think we will find examples for whatever we want

'sid

 

[bob58o]

bolts are typically used to create bolted joints, which is a combination of the nut applying a clamping force, pinning the joint sideways. This is why many bolts have an unthreaded shank — it creates for a stronger and more effective dowel. Therefore, unthreaded shanks have long been a defining characteristic of bolts when comparing them to their screw counterparts. - https://monroeengineering.com/blog/bolts-screws-and-studs-whats-the-difference/

A happy medium?
Or now a bolt needs an unthreaded shank and a nut?

 

[Whitetrashrocker]

What about having the best of both worlds?

 

[ezcome-ezgo]

What about helical vs spiral threads? Huh? What do you think about that?

 

[bob58o]

Machinery's Handbook... pg 1538 -1539

http://allaboutmetallurgy.com/wp/wp-content/uploads/2016/12/Machinery_s_Handbook_29th_Edition.pdf

Differentiation between Bolt and Screw.

—A bolt is an externally threaded fastener
designed for insertion through holes in assembled parts, and is normally intended to be
tightened or released by torquing a nut.

A screw is an externally threaded fastener capable of being inserted into holes in assembled
parts, of mating with a preformed internal thread or forming its own thread and of
being tightened or released by torquing the head.

An externally threaded fastener which is prevented from being turned during assembly,
and which can be tightened or released only by torquing a nut is a bolt. (Example: round
head bolts, track bolts, plow bolts.)

An externally threaded fastener that has a thread form which prohibits assembly with a
nut having a straight thread of multiple pitch length is a screw. (Example: wood screws,
tapping screws.)

An externally threaded fastener that must be assembled with a nut to perform its intended
service is a bolt. (Example: heavy hex structural bolt.)

An externally threaded fastener that must be torqued by its head into a tapped or other
preformed hole to perform its intended service is a screw. (Example: square head set
screw.)


I'm pretty sure you can encompass the entire Machinery's Handbook Differentiation with ....
Nut = Bolt
No Nut = Screw

 

[ezcome-ezgo]

You could have just read that first and saved a few million bytes of interweb bandwidth.