What is Screw: Definition and 134 Discussions

A screw and a bolt (see Differentiation between bolt and screw below) are similar types of fastener typically made of metal, and characterized by a helical ridge, known as a male thread (external thread). Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread (internal thread) in the matching part.
Screws are often self-threading (also known as self-tapping) where the thread cuts into the material when the screw is turned, creating an internal thread that helps pull fastened materials together and prevent pull-out. There are many screws for a variety of materials; those commonly fastened by screws include wood, sheet metal, and plastic.

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  1. Saladsamurai

    Solving a Power Screw Question - Get Help Here

    I was reading through some examples in my Design text when I came across this one. This was their solution: I am not sure that I completely follow it. Can someone help shed some light on what's going on here? I am assuming that the specimen to be put under tension goes where the "B"...
  2. B

    Schools Advice for a Young High School Student (Where did you screw up?)

    Hi everyone, I was just wondering what were the mistakes you made along your career path in any of the sciences, and what would you recommend any young person doing to avoid these mistakes...
  3. C

    Did I waste my youth by making wrong career choices?

    I was just wondering how much damage have I caused myself by wasting the few years in the past? I started career fairly early. I learned calculus back when I was in the seventh grade. I then went on to take college-level mathematics starting from 9-th grade on, and college level physics starting...
  4. G

    Removing Socket Cap Screws With Lok-Tite

    OK, not the usual kind of question posed here, but not entirely off-topic either. Last weekend I was trying to remove a couple of socket cap screws (recessed hexagonal drive) that were installed with lok-tite (thanks to the lawyers). After multiple applications of heat from a propane torch...
  5. E

    Refridgerator Problem: Where Did I Screw Up?

    Homework Statement How long would a 2.90 kW space heater have to run to put into a kitchen the same amount of heat as a refrigerator (coefficient of performance = 2.58) does when it freezes 1.45 kg of water at 19.4°C into ice at 0°C? Homework Equations COP=Q_c/W Q_h=Q_c + W Q=cm(deltaT) Q=mL_f...
  6. K

    Method To Exert a Downwards Force (Force created by screw threads?)

    I am trying to come up with an automated method to exert a force of around 250N downwards onto a plate. The possibilites that i have looked at so far are Weight (although this has been discounted due to the size of the weight that would be needed), Hydraulic and Pneumatic systems. However...
  7. M

    Magnetic Liquid Screw Propeller

    Is it possible or will it be possible to keep some magnetic liquids in some desired geometry and use as a traditional screw propeller ? Is it patented or visioned before ? Best regards , Mustafa Umut Sarac Istanbul
  8. R

    Embodiment calaculations for a automated (screw) bike seat post

    Homework Statement I am currently tring to work out the torque that is required to lift a bike seat of mass 2kg at a rate of 10mms-1 with a given screw thread and nut. how would i go about this? Also is it possible to calaculate the shear force experienced by the thread of the screw and...
  9. D

    Linear force transfered from an electric motor to a screw.

    I have a 1/4 hp electric motor. I plan on attaching a piece of threaded rod to the shaft of the motor. If I put a nut on the threaded rod, and welded 2 bars to either side of the nut (running parallel to the threaded rod) how would I calculate the amount of linear force I am exerting? The...
  10. M

    Where to Find 5mm x 30mm Allen Head Thread Forming Screws?

    I am in search of 1000 5mm x 30mm Allen Head Thread Forming/cutting zinc plated steel Screw but can not seem to find this particular screw anywhere! Does anyone know where I can find this screw? or possibly have it manufactured? Thank you, Mooref2
  11. T

    Can Guacamole Go Wrong?

    I've always seen the "hamburger and fries $4.00 " handwritten on the bottom of the menu at the Mexican restaurant across the street, but never tried it. It just didn't seem right, but I went ahead and got it for breakfast this morning. It was quite a bit of food for four bucks, but they threw a...
  12. M

    Did i screw up getting a good letter of rec - bizarre story

    as i just finished my REU and was on my way to take my flight back home. one of the students offered to give me a ride to the bus stop so that i can take the bus to the airport, which is about an hour away from school. this is where the main problem occurred: there were 2 bus stops near the...
  13. rohanprabhu

    Did Nike Screw Me? My Experience with AirMax 360 Shoes

    I purchased a pair of Nike AirMax 360 [size 13] shoes from a Nike retail outlet in Vadodara, GJ, India. I bought it during a sale for Rs. 10,000 (250$). I got it at 40% discount i.e. at Rs. 6000 (150$). These shoes have air-padded soles i.e. the soles are filled with pressured air [or whatever]...
  14. S

    Do you guys think this professor is trying to screw me over?

    I've been taking this numerical analysis class for 6 weeks. I should be getting an A+ in the class based on my understanding of the material and how hard I work. However right now I only have a B.(I've working my ass off to boost my medicore gpa) On the midterm there was a proof where we had...
  15. A

    Calculating Allen Screw Diameter with Parallel Load

    Hi, Please help me in solving this problem. I need to calculate the dia of the Allen screw. I have an assembly (2 parts). Hydraulic fluid is passing thru the drilled hole. I need to calculate the dia of the Allen screw (for fastening 2 plates). The load is acting parallel to the fluids...
  16. B

    Equations to do with the z distance of a screw helix.

    Homework Statement You have a screw with the distance between the threads being equal to 0.1mm. It takes a torque of 10Nm to turn the screw about 2pi radians. What would the torque be to turn a screw with the z distance equal to 0.2mm. Explain your reasoning. Homework Equations Not sure...
  17. A

    Screw threads and bearings (how to )

    Hi everyone I am trying to learn how do I correctly draw, with a ruler (where are milimeters visible as much as possible) and pencil, on already given surface screw thread and on another surface (different task) how do I correctly draw, let's say, pair (or it can be just one too - study of...
  18. A

    Is it me being retarded or did ETS screw up again?

    Homework Statement K this is a question from GRE Testbook. At Blinky Burgers restaurant, two hamburgers and five orders of French fries cost the same as four hamburgers and two orders of French fries. If the restaurant charges $1.50 for a single order of French fries, how much does it...
  19. wolram

    Invaluable Tool: Multi Positional Obstructed Screw, Nut, Bolt Starter

    It is a multi positional obstructed screw, nut , bolt starter, it is very functional and can save hours of build time, material costs are well below a £1, the tool could be a throw away or reusable for repeat jobs. Would there be a market for such an invaluable tool?
  20. S

    Edge, Screw, and mixed dislocations

    Does anyone have an idea as to the relative abundance of each of these types? Why will one type occur over the other in a given situation? Thanks, -Scott
  21. D

    Optics did my professor screw up?

    Homework Statement A cat is standing 1m in front of a mirror. a virtual image is formed 10.0m behind the mirror. what is the radius of curvature for the mirror? Homework Equations 1/f = (1/do)+(1/di) f=+/-(1/2)*R The Attempt at a Solution (1/1m + 1/10m)^-1 = .909 .909*2 = 1.82...
  22. S

    What is the Relationship Between Linear and Rotational Speed for a Screw?

    Could somebody help me with this? Let’s say I have a screw that is 0.25” dia. I want to screw this screw into the wall. First question: If I turn this screw 2 times around its axis, how far the screw will go into the wall? Second question: If I rotate the screw at 10 RPM what is its linear...
  23. E

    How Do You Calculate the Mass of a Single Screw from Multiple Cup Weights?

    I have been given the masses of 5 cups, each with a different amount of screws inside. 1st cup = 13g 2nd cup = 19g 3rd cup = 8g 4th cup = 26g 5th cup = 38g I need to find the mass of a single screw. I was not given any equations or data besides those masses I have no clue how to approach this...
  24. W

    Finding 1/8" x 1/16" x 3/4" Allen Screws

    I'm looking for a couple of Allen screws hard to find I guess. Cap diameter 1/8 " Thread diameter 1/16 " Length: 3/4" I searched everywhere with no luck.
  25. F

    About a screw (circular motion)

    Hello folks! I am about to finish the chapter "Circular motion" in my script but there is the following problem that is keeping me busy and I would very appreciate every help I can get! A M10-Screw with a pitch of 1.5 mm (means, that the screw goes 1.5 mm per revolution into the thread) is...
  26. P

    Non Magentic Screw Driver Magnetized

    I have a lot of electronics, computers, CBs, HAMs located within my room. During a few events I left a non-magnetic screw driver on the floor. The next day it became magnetic. It was slightly humorous. :-p
  27. wolram

    Sonic Screwdriver: Vibration Tool for Loosening Fasteners

    Ok it is a doctor who tool, but vibration is notorious for loosening nuts bolts screws, otherwise there would be no need for locking wire, spring washers etc, so would it be possible to have a vibration producing tool that could undo stuborn fasteners, such a tool would be an invaluable tool...
  28. F

    HELP Howto design power screw drive

    For 10kN vertical load,I just need some instructions to follow and if someone can provide schemes and more details will be great:))))THANKS!
  29. G

    Screw Gauge Pitch: Length of Main Scale Division?

    In a screw gauge, the pitch is defined as the distance traveled in one rotation. Is it also equal to the length of one main scale division? If the length of one main scale division is not given, then can we take it to be equal to the pitch? Or do we take it as equal to some other default value.
  30. J

    Solving Horizontal Force of Screw on Shelf Bracket

    A shelf bracket is mounted on a vertical wall by a single screw, as shown in Figure P12.59. Neglecting the weight of the bracket, find the horizontal component of the force that the screw exerts on the bracket when an F = 86.0 N vertical force is applied as shown. Ok so we have three...
  31. M

    -did my professor screw up the igan vector? matrices fun weee

    Hello everyone, we found 3 igan values: 1, 2, 3 for the last case: 3 we came out with 0 -1 0 0 -1 0 2 -2 -2 he wrote b = 0, a = c; then said igan vecotr is: 0 1 1 but clearly shoouldn't it be: 1 0 1 ?
  32. S

    How Power Screws Work - Explained with Illustrations

    hi does anyone knows how a power screw works, illustrations would be helpful.. thanks ss
  33. L

    Understanding the Right Handed Screw Rule: A Comprehensive Explanation

    can anybody explain me right handed screw rule
  34. T

    Solar Water Heater: Ideas & Advice for Arizona Residents

    I only use gas for heating water, so I'm considering a solar water heater. It seems dumb not to go solar here in Arizona. I was wondering do any of you have a solar water heater? How do you like it? Do you have any plans on how to build one?
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