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Lv 6
? asked in Home & GardenMaintenance & Repairs · 1 decade ago

Just for fun, I ask the following?

I saw a question about taps and dies very recently, and the answers given were good. Just for fun though, can anyone tell me the difference between a bolt and a screw, and at what size they differentiate between the two? Then, explain in terms of use, how each one is different from the other. Don't go getting all cocky here, it's not as easy as you might think. I'll leave it up for 24 hours and see how many answers come in, then award the points (big deal, but what else is there?) to the best and most complete answer. I hope this gets a few minds working in overdrive. {grin}

Update:

To Jim. Well, you started off correctly, but then wandered into the realm of silly. Next?

Update 2:

Pete. Yup, I should have been even more specific about the screws. I should have said "machine screws". Even so, this part is not *quite* correct.

"and any machine-treaded fastener (with a head) was called a 'bolt' at any size down to eye-strain in diameter."

I agree that they do get called bolts sometimes, but they are not. Question is, what is the difference? Check the Machinists Bible, first page of the section of bolts, screws, nut, and washers.{wink} I didn't know the exact difference either, but it's always fun (in my opinion) to learn something new.

Update 3:

Acording to the machinists bible, "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 threador forming it's own thread and of being tightened or released by torquing the head."

so it's the method of tightening and releasing that diferentiates the two. Also, bolts are generally 1/4" and larger, whereas screws are 3/4" and smaller, overlaping sizes until they reach #12 and smaller.

Just some tyrivia.

Update 4:

I just wish I could give the *correct answer* to all who participated in this.

3 Answers

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  • hrly
    Lv 4
    1 decade ago

    Ok I'll give it a shot. Bear in mind I'm not a machinist or engineer, just a handyman.

    To my mind a bolt is a screw together with a nut that provides the compression needed to complete the task.

    A screw uses the threads to engage the task directly to provide the compression.

    If you put a nut on a screw it then becomes a bolt.

    Source(s): Just my guess. I'll be interested to see the correct answer. :)
  • Jim W
    Lv 7
    1 decade ago

    All bolts have a machine thread. All screws have threads and some are machine threads. All men are animals, all animals are not men.

  • smokey
    Lv 7
    1 decade ago

    A screw is what you get when you pay too much for something. A bolt is what you do after you sell something for too much.

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