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.

View More On Wikipedia.org
Recent contents Top users
  1. D

    Bolt screw shear strength calculations

    Hi guys, I have an electric motor that comes with a flange to be bolted on a plate horizontally so that the 4 screws carry the weight of the motor and the momentum it creates on them. Could you direct me to how to calculate if the given screws and nuts stand up to the load? Perhaps an example...
  2. D

    Torque required to move a lead screw

    Hey everyone, I have a quick question. I'll first describe the setup... I have a lead screw that is vertical with a carriage attached parallel to it (weighing roughly 50 lb). It is attached to a perpendicular gear at the top. Oh and the nut attached to the lead screw I believe is nylon. The...
  3. Femme_physics

    What's the point of this screw?

    Hi guys. Student here :) http://img254.imageshack.us/img254/6811/smict.jpg At "1", What's the point of putting a screw here? It doesn't really connect anything...why not make the part without this hole to begin with?
  4. M

    Screw and mating thread strength equations

    I am designing a mating male and female threaded interface, where the nut is much weaker than the male thread. I need to be able to calculate a few things: A. The maximum force (as preload) required to reach the yield point of the nut material. B. The torque required to achieve the above. The...
  5. H

    Screw Pump Sizing: Calculations for Inverted Pumps

    Does anyone know where i can get the calculations for sizing an inverted screw pump. Inverted being that there is no screw but the fins art attached to the inside of a pipe and the pipe is rotating. I am moving any where from 150 to 400 lbs of dry powder per minute, depending on the amount of...
  6. P

    Is it possible to screw off the cap of an Argon/Oxygen-bottle?

    Maybe strange question, but I would like to use an Argon/Oxygen 20 L bottle to load with water, NaOH and Al to make hydrogen for a fuel cell project. So, to load this bottle I'm thinking of screwing off the cap, then put it back again. I can imagine this is very hard tighten. I would like to...
  7. G

    How many mathematicians does it take to screw in a light bulb?

    So I just saw this joke and I thought y'all might get a kick out of it (at least those who have read one of the bourbaki books) Q: How many Bourbakists does it take to replace a lightbulb? A: Changing a lightbulb is a special case of a more general theorem concerning the maintain and repair...
  8. M

    Motor power for screw conveyor?

    Hi this is the case I have to find a suitable motor for a screw conveyor with mass flow of 200g/h lenght of a crew 0.5m diameter is 100m it works with small particles of coal and it need to work for 1 rpm help??
  9. D

    Troque calculations for a direct coupledmotor and ball screw

    I know the formula T=F*D but having problems wrapping my head around this problem. I want to direct couple a stepper motor with a .5"D shaft to a .75"D ballscrew. The motor has 400 oz inch torque but since the motor shaft is .5"D or .25" radius How do I calculate the Torque at .25" radius? I...
  10. N

    Automotive Does Adding a Soft Starter Affect the Lubrication of Air Compressor Components?

    we have an air comporessor driven by dc series motor direct start the the system work and stop many times as the air decrease in the main resirvoir , thus the motor temperature get more hot as an electirical engineer i want to protect the motor starting by add soft starter to it But the male...
  11. E

    Drawing a ½”-13 UNC x 1-1/2” Cap Screw with Hex Nut and Plain Flat Washer

    http://i46.tinypic.com/1zg877r.png So I'm trying to draw a "½”-13 UNC x 1-1/2” long round head cap screw with hex nut and plain flat washer" and this is what I came up with. How do I draw it with the hex nut and the plain flat washer? What does it look like?
  12. G

    Trouble with Estimating GaN Screw Dislocation Density

    Hi everyone. Recently, I did (002) XRD scanning to get the rocking curve of a sample of GaN. From the measurement, I found that the FWHM of the sample is ~1.35 degree. I tried to convert it into radian unit using this formula: angle in radian=angle in degree x π /180 (degree). I got the...
  13. C

    Why Won't My Archimedes Screw Elevate Water?

    Hi guys. I'm *attempting to make* an archimedes screw for my engineering project. The only stipulations for this project are as follows: Create a machine that will move water from point A to point B The machine must be powered by my professor's desk fan. So, I bought a small wooden...
  14. M

    2 post lift with lead screw and rope drive

    Actually i am using lead screw drive by motor along with rope drive. If you will see the attachment, yuo can clearly understand the working principle. In this working priniciple, when we used to start the motor, carriage power use to go up through lead screw drive.Rope is connected to this...
  15. V

    Optimizing Gear Design for Screw Jacks

    i have to design gears for a screw jack. i have initial rpm 1500 and final rpm 100. my gear at the point of the power screw is 0.04 m and i want to calculate the diameter for the other 3 gears. can you please help me thank you
  16. Gh778

    Torque on a square screw full with water

    Hi, I would like to calculate the torque on a color square screw full with water like the drawing show. All grey screws don't move or turn, only color screws can turn (and so move up or down). Color screws are square (see top view for that). There is water between color screw and grey scew...
  17. O

    How to remove the magnetic property for screw driver?

    Referring to following video, if I magnetize my screw driver having a magnetic property in this way, I would like to reverse the process, is there any approach to completely remove this magnetic property? so there is no magnetic property from my screw driver. Does anyone have any suggestions...
  18. D

    Making a vacuum seal with a screw?

    I apologize for my lack of mechanical term knowledge. I'm looking for a type of screw I could use in a project. Sorry if the thing is unrealistic or if the part is obvious. I attached a sketch of what I'm looking for. The screw would never be completely out of the hole like the sketch...
  19. K

    How are Screw Conveyers Manufactured?

    Hello, Does anyone have any idea how the screw conveyers in these photos would be manufactured? http://www.bwsinclair.com/Products/Live%20Bin%20Bottoms.htm It's the variable fin length that I don't understand - could this be extruded? Any clue how it would/could be done? Thanks for your...
  20. C

    Use a wood screw or a bolt & nut?

    I have what I think is probably a simple problem for someone with the right experience. I happened upon this forum while using Google. The drawing below (not to scale) shows the basic setup. There is wood mounting block. Adjacent to the mounting block is a 1/4" thick piece of wood with a...
  21. W

    Screw Torque Conversion for Power Modules: EE vs. ME Perspective

    Hello MEs - I am an EE and have customer that insists in not following our qualified mounting instructions for a power module: Our instructions M6 8.8 screw torqued to 2.5 min to 5.0 Nm Max. Customer is using NAS 1802 torqued to 25 in lbs -->> Is this a suitable conversion? Of...
  22. J

    Free rotating set screw attachment (like used in c-clamps)

    I'm designing something in which an insert fits into a piece of steel square tubing. The insert is held in place by a set screw threaded in the insert, which is in turn loc-tited into an aluminum "plug" (wider surface area) and is clamped to the inner wall of the square tubing with a hex wrench...
  23. R

    Cold Rolling for Power Screw Threads: Advantages & Disadvantages

    For threading of Power screws ( like in a car jack with square/trapizoidal threading ), why is cold rolling preferred to normal material removal machining ; say turning on lathe. Or is cold rolling even preffered?
  24. J

    Finding mass of a single screw lab No calculations XD

    I have been given the masses of 5 cups, each with a different amount of screws inside. I am asked to find the mass of a single screw. The cups themselves are all equal in mass and the screws are all equal in mass as well. I subtracted all the cups from each other to get a bunch of numbers...
  25. J

    Finding the mass of a screw lab.

    I have been given the masses of 5 cups, each with a different amount of screws inside. I am asked to find the mass of a single screw. The cups themselves are all equal in mass and the screws are all equal in mass as well. I know you are supposed to subtract the cups from each other to...
  26. Z

    Velocity screw description of a robot end-effector question

    look at the above image, the red coordinates is attached to the robot end-effector, and the other one is the base.coordinates. Now, As we know, the end-effector can do any rigid motion, so if a point P is attached on the robot end-effector. we can calculate the velocity of the point P. The...
  27. Z

    Help on velocity screw description and velocity propagation

    When reading some papers in robotics, I found two different ways of the velocity screw and velocity propagation. This is one description of calculation a point's velocity in the paper "A tutorial on Visual Servo Control", we say paper A. The author said: The rotation acts about a point...
  28. D

    Archimedes Screw: Power Generation in Pulsating Environment?

    Hello, I am wondering whether an Archimedes screw generator would work in a pulsating environment. What I mean by this is does the screw require constant flow in order to generate electrcity? Or could I put such a screw in a pressure driven yet zero-head environment(similar to blood flow)...
  29. C

    Design Lead Screw for CNC Machine - 48 Steps, 1mm Per Step

    Hello, I am going to build a CNC machine and for that I need a lead screw. My stepper motor has 48 steps in one cycle. I want to make move 1mm per step and please make a CAD drawing so that I make this screw from mechanical workshop. Also please suggest me the software to build such design...
  30. D

    Deformation of Allen Head Screws: Impact or Wear?

    Hi all just a simple question about the hole of the Allen head screw becoming round/circular after repeated use of a Allen key on it. From what I read so far it should be a form of wear. I am thinking of abrasive or impact wear, but not sure which is it. Can anyone answer this? Thanks.
  31. D

    Will Genetics Limit My Future Education?

    I was born with a myriad of mental issues ranging from psychosocial-immaturity, ADHD, sensitivity to noise and various other factors that correlate closely with Asperger's syndrome. My dad is PhD in Physics with a focus in cryogenics and my mom is a French existentialist artist (weird childhood...
  32. S

    How Do You Select a DC Motor for a Scissor Lift Using a Power Screw?

    Can anyone tell me . if I am going to lift up a scissor lift using power screw drive by a motor, the highest torque is during lowest position before lifting so this is a maximum torque and the speed RPM is the speed i wish to lift scissor up with a turn equal to a lead of the screw? So during...
  33. D

    Designing a Power Screw for Minimum Turns and Maximum Safety

    Hi all 1. The pressure device described in the pic needs to apply a force of 10kN on the 'square product' below in order to work. The worker can apply 100N force while the 'arm' is 350mm. Assuming the friction (mew) can change from 0.05 to 0.15 and the thread is square (alpha=0) design a...
  34. H

    A basic question from screw jack coefficient of friction

    why the coefficient of friction of screw jack of two pulley is negative in lowering state?
  35. B

    Schools Will going to a community college screw my chances for grad school?

    Hello everyone, I'm currently a senior in high school. Due to financial circumstances and other reasons, there is a good chance that I might be headed to a community college next fall. I'm planning to go there for the usual 2 years, and transfer to a state school and major in math, hopefully...
  36. S

    Measuring Vibration on Screws in Vehicle Flanges

    Hi guys, in my company we have seen a lot a failures on a flange, in particular one flange screw strips. This flange is mounted in a vehicle and it support some hydraulic pipes. The designer thinks vibrations should cause the failure and so he suggests me to measure the flange acceleration along...
  37. D

    Lead screw and frame calculations

    Hi I am new to the design game as it where and I have scoured books and the internet looking for calcs, examples, help with a design I am putting together which involves raising and lowering a heavy object using a lead screw. I know its not strictly CNC stuff but I believe someone may be able...
  38. H

    Using a hexagonal key on a square-headed screw

    Homework Statement Suppose that you want to undo a square-headed screw of side a using a key that has a regular hexagon hole of side b. What relations must hold between these two number in order for you to succed? Homework Equations Basic geometry and trigonometry. The Attempt at a...
  39. M

    Power screw horizontal applicaion FBD

    Hello, I have been trying to set up a free body diagram for a power screw in a horizontal application. Every example I find they are using a power screw to lift or lower a load not move it left to right. I have attached the example from the textbook, along with my work so far...
  40. R

    How does a partially threaded screw exert compressive force across a fracture?

    Hello, I would be pleased if someone could explain me how a partially threaded screw (lag screw) exerts compressive force across a fracture for instance. I want to know how this is different from a fully threaded screw, i can be very happy if someone could put all the forces in both systems...
  41. A

    How Do You Calculate Horizontal Force in Power Screw Problems?

    Homework Statement http://doc-0k-c0-docs.googleusercontent.com/docs/secure/18gv8eitjbbf7kd81j9pkj97r6uu2aio/enhpjst14oh50re9pqu959gslq83hok3/1275825600000/06477642192900593696/06477642192900593696/0ByXII_HcY1w-ZjI2ZDdiNzUtZWQ1ZC00NDIxLTgxMGMtMGJjMTNlMTJlMTBk Homework Equations...
  42. S

    How Much Work Does It Take to Drive a Screw into Wood?

    Homework Statement It takes 20 turns to drive a screw completely into a block of wood. Because the friction force between the wood and the screw is proportional to the contact area between the wood and the screw, the torque required for turning the screw increases linearly with the...
  43. S

    What is the total work required to drive a screw into a block of wood?

    Homework Statement It takes 20 turns to drive a screw completely into a block of wood. Because the friction force between the wood and the screw is proportional to the contact area between the wood and the screw, the torque required for turning the screw increases linearly with the...
  44. M

    Ball screw actuator mechanism

    I have a reclining mechanism which moves by and down. It is X framed, just like an ambulance stretcher. It has to be able to raise its own weight through a vertical distance of 610mm. The length of the stretcher is 2m, and the distance between the wheels is fixed at 1.2m. Can anyone help me go...
  45. S

    I can't figure out how to keep this screw from loosening

    I'm making a simple "thing" to test out a simple part of something much bigger I'm designing, but am not experienced enough to figure out what I can do to keep the main screw from loosening. Is it even possible to keep the screw from loosening under vibration? If so, what can I add (and where)...
  46. J

    How Do You Determine the Permeability of Steel Screws Used in Electromagnets?

    Hello All, I'm working on a project involving the use of electromagnets and I am trying to do some calculations to predict the B-Field strength of the coils I make. For the core, I'm just using some common 1/4-20 steel machine screws (the common ones you can get from Home Depot and Lowes) but...
  47. A

    How Do I Calculate the Pitch and Depth for a Cap Screw?

    how to do calculation for cap screw?how to find pitch and depth for screw?? is it similar to nut and bolt screw?? if it is then how?? if not then how?? please help!
  48. B

    Force on the top screw in a hanging basket scenario

    Homework Statement Hi and Thanks to anyone that takes time to help! This is not a homework thing but a 'discussion' with friends. Please excuse my crappy drawings... The measurments are not important only that it is the same frame either with strut or reversed for tie. The difference in...
  49. K

    Have I finally found my passion in math and computer science?

    So During my high school year from gr 9-12, i screwed aroudn too much. I never did any work or the least amount of work possible in order to pass. So basically i got 50s. Then last year, i tried our stone masonry thinking it was the thing that i really wanted to do. Well it wasn't and now I'm...
  50. negitron

    Need a fastener locking mechanism for #8-32 NC screw.

    I have a .380 auto handgun which uses a #8-32 NC cap-head screw to retain the trigger guard. During firing, the mechanical shock of the cycling action serves to rapidly loosen this screw regardless of the torque used to tighten it down. I cannot use a standard star washer because they're...
Back
Top