ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Bolts & Screws

Updated on December 20, 2009

Bolts and screws are a group of devices used to hold objects together or to fasten one object to another. A bolt or screw consists of a metal rod with a spiral ridge, called a screw thread, running continuously around the rod. Most bolts and screws have a head, or a piece of widened diameter, at one end of the rod.

Screw threads are manufactured in several standard sizes and shapes. The United States, for example, has traditionally used a system called the American standard, and Great Britain has used the Whitworth standard. Several metric screw-thread systems are used in continental Europe and other areas. In 1948 the United States, Great Britain, and Canada adopted a common screw-thread standard, called the unified thread standard. This new standard is now in wide use and is expected eventually to replace the older standards.


Most bolts are used in combination with nuts. A nut is a small block of metal with a hole through its center. The inside surface of the hole has screw threads that fit the threads of the bolt. When a nut and bolt are used to join parts, the bolt is inserted through holes in the parts being joined, and a nut is screwed onto the end of the bolt. As the nut is tightened, the parts to be joined are drawn together between the nut and the head of the bolt.

Bolts and nuts are made in many shapes and sizes. Machine bolts are used on automobiles, airplanes, and other machines where a close fit is required. These bolts usually have square, hexagonal (six-sided), or circular flatheads, and the nuts are usually square or hexagonal. Stove bolts, used on electrical equipment and household appliances, have flat or rounded heads. Carriage bolts have roundheads and are threaded only at the end. A short square section just below the head, when placed in a square hole, keeps the bolt from turning when a nut is screwed on the end of the, bolt. Carriage bolts are used in woodwork and in fastening castings and forgings. Eyebolts, with heads shaped like upright loops, are used to support cables, chains, and metal rods. The expansion bolt, used to fasten objects to masonry, is fitted with a long split nut. The nut is placed in a hole in the wall, and when the bolt is screwed into it, its two pieces are forced apart to provide a firm anchor. Toggle bolts, used to anchor objects onto a hollow wall, have a nut that looks like a pair of folded wings. The wings spring open when placed inside the wall and thus preĀ­vent the bolt from being pulled out.


Screws resemble bolts, but they usually are not used with nuts. Many screws have a slotted head into which a screwdriver can be fitted. A machine screw is usually inserted through a hole in one of the parts to be joined and then screwed into a threaded hole on the other part. A nut is therefore not needed. A wood screw is usually driven into an unthreaded hole whose diameter is slightly less than that of the screw.

Like bolts, screws come in many forms. Cap screws, used in machine tools and for assembling automotive and aeronautical parts, usually have hexagonal or flat heads. Machine screws are similar to cap screws but are usually smaller. Setscrews prevent sliding motion between two parts, such as a pulley and its shaft. Self-tapping screws are made so that they can cut threads into unthreaded holes.


    0 of 8192 characters used
    Post Comment

    • Steel Engineer profile image

      Steel Engineer 

      5 years ago from Kiev, Ukraine

      Great hub with good details and effective graphics. Nice.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)