Types of Screws

There are a huge variety of fasteners for different jobs. It is a big job deciding on the right kind of fastener or screw and then finding it. Here is a pictorial guide I found on the internet [http://justpaste.it/7ux]. Looks pretty useful.

 The website of D. Lawless Hardware, an American company, provides a lot of information on screws in general. I have extracted some information from there website.

Basic Types of Wood Screws
Wood screws are classified by the type of drive, the shape of head, its length, and whether it is designed for wood or metal; this page refers to wood screws only.

Types of Drives
Drive refers to the indented shape on the screw head used to turn the screw. There are many different types of drives. Here we are only covering the four most used drives. These include slotted (flathead), phillips (crosshead), square, and pozidriv. A brief description of each drive is below with a picture at the bottom to illustrate each ones unique design.



SLOTTED/FLATHEAD: This is the original screw drive. You find these everywhere, though the practice of using screws with slotted drives is on the decline because the screwdriver slips out of the slot, particularly when you are applying heavy torque to really tighten down (or loosen, for that matter) these types of screws.

PHILLIPS/CROSSHEAD: This screw drive type is very popular - and again, you find them in a very wide range of applications. Common sizes are Phillips  #1, #2 and #3. The most common Phillips size is #2.

SQUARE: Square recess are being used more and more as they are very resistant to cam-out, which is a fancy way of saying the tip of the tool does not slip out and mar the screwhead very easily. Commonly found in two sizes: Square #2 and #3.

POZIDRIV: This screwhead isn’t seen very often in the U.S.A., though it is very common in Europe. It looks a lot like a Phillips screwhead, but it includes 4 more contact points. Common sizes are Pozidriv #1, #2 and #3.

Screw head types
In addition to the different types of drives, there are a variety of head designs, each meant for a particular kind of job. Flat head screws are typically found on wood screws that are usually countersunk, pan heads grip one part to another with considerable force and so on.

Screw Head Types

Threading and Point Types
Most wood screws have a common "pitch" to the treads, but some have a thread with a steeper incline. We simply call this a "fast" thread, but they are technically Type A screws.Think of this as a road going up a mountain; the steeper the road, the sooner you get to the top.
Also in reference to threads you will see "8-32". This is the common knob and pull screw thread. The "8" refers to the size (diameter) of the screw, and the "32" means it has 32 threads to the inch. Most of the screws for mounting hinges are self-tapping (they tap their own mating threads in wood) type AB (they have more threads per inch and are more effective in brittle materials like wood than Type A).

Threading on the shank is designed specifically for wood; wood threads have a tapped screw while sheet-metal screws have mainly a parallel thread. Wood type screws are also normally used for securing into wall plugs. Screws for chipboard usually have 2 threads the full length of the shank.

US Standards
One of the great things about the West is the standardising of most hardware items. Once standardised, there can be no confusion and tool can be built accroding to standard specifications. Here is a chart that shows standard screw sizes:




Indranil Banerjie
13 March 2012

Comments

  1. Thanks, this is really informative. My local hardware owner will not know the English terms. I plan to take a print out of this to show him what I need the next time I go there. I also prefer to go for stainless steel screws for woodworking as opposed to the usual galvanized iron ones. Do you think that is an overkill?

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  2. Nope. I prefer ss screws myself. Look cleaner, feel stronger and don't rust.

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  3. Thanks for putting this all together in one place - really handy. You cant imagine how helpful your site is for the Indian DIY man :)

    I've been using brass screws to fix brass hinges on my windows. Would you suggest SS is a better option?

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  4. Thanks for your comments. Brass screws are fine, especially if they are good quality. But brass screws are not very strong, certainly not as strong as steel. But if you have been using brass screws for your window hinges without any problem that is absolutely fine.

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  5. Hi indranil
    I am from shimla and just picked up woodworking as a hobby. Thank u for starting such an informative blog. It has been a great help in chosing my hardware. Where can i buy philips head wood screws in different sizes online as they are not available with any hardware store in shimla or chandigarh.

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  6. Don: For some reason Philips head wood screws are difficult to obtain in India, There are plenty of good stores in Chandigarh where you might try.

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  7. Thanks sir
    have tried in chandigarh but not been able to find them..

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    1. Sorry to hear that. I am searching for the same in Delhi/NCR. Will let you know if I find a source.

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  8. Can i use a cordless screw driver on a slotted head screw. I am planning to buy a cordless screwdriver. I hope it will not slip on the screw head

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    Replies
    1. Better to use regular screw driver for slotted screws.

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  9. This comment has been removed by a blog administrator.

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    1. Sir any violation due to which my last post was removed?

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  10. Indranil, thanks for putiing this up.

    Phillips screws are available in small quantities in some shops in Mumbai.

    I found driving screws into wassl with my drill machine (Bosch GSB 13RE) to meltdown the cheap plastic Rawl plugs and adapt to the threads of the screw and the wall. This secures the screw as well as the teakwood plugs.

    My Bosch electric screwdriver does not hold charge anymore and has to be used wired only. Reserved only for the fairings on my bike now. Not a recommended buy.

    Do you recommend using Screw Extractors to remove stripped screws. Any other options?

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    1. Himanshu: I have found using screw extractors to be pretty tough but I cannot think of any other alternative.
      What is wassl, by the way?

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    2. I can find Philips head screw easily in Chennai. I just bought them form nearby hardware shop for my first project. Let me know if you need any help. Also they are readily available in most of indian industrial ecommerce sites.
      And thanks for this informative post.

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  11. Very nice 👍. Agree with the US standardisation, in fact one visit to the home depot sets you drooling :)

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  12. Thanks Indranil for posting the information on screws. I now have a better awareness. I am now in the process of taking woodworking as a hobby and your blog posts have been very helpful in understanding many aspects related to woodworking. Are you aware of any woodworking hobby group or individual in Coimbatore?

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    1. Thanks Raj but I don't know any woodworking enthusiast in Coimbatore. However you could contact Vinay Oommen (vinaytoommen@gmail.com) who is based in Vellore. He might be able to help.

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    2. Hi Raj, i just moved to coimbatore (love this city) and have been a fan of Indranil sirs blog for quite some time.Reading his blog allowed me to take the plunge into woodworking a little over a year ago and i got a circular saw and router based on the advice in his blog. I work with pallet/recycled wood for the most part as i love the rustic feel and look of it and have built all my furniture at home as well as for a few friends. i dont blog much but i do have an instagram page that you can check out: https://www.instagram.com/crazyfindian/

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    3. Great work! Awed that you were prompted by this blog to take to woodworking. Wishing you happy times in Coimbatore.

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    4. Thank you sir, the issue was getting tools. i was initially based out of hyderabad and struggled to find simple things like drywall screws in the sizes that i wanted. I cant find kreg screws and use drywall or stainless with a small washer. i prefer stainless because the drywall has very less shear strength and tend to have their heads break off :)..
      But anyways, i digress :).. love your blog :)

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  13. Dear Mr Indranil
    I recently acquired Kreg K5 pocket hole system from US. But than I realised pocket hole screws are not available in India. Getting them from US is turning out to be expensive affair. Is there any alternative available in India?. Are they available online. I stay in Manali , Himachal.
    Regards
    Col Amitabh

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    1. Unfortunately a lot of us have been grappling with the same problem. There are no suppliers of that type of screws in India. People make do with regular chipboard screws with washers.

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    2. I saw the video of the Pocket Hole system. You can do what Indranil recommends and use a Phillips or Pozi Drive screw available easily as Stainless Steel in fittings shops. Alternately look up:

      https://www.alibaba.com/premium/pocket_hole_screw.html?src=sem_ggl&cmpgn=824536950&adgrp=42760686699&fditm=&tgt=kwd-295548705100&locintrst=&locphyscl=9062259&mtchtyp=b&ntwrk=g&device=c&dvcmdl=&creative=194594083580&plcmnt=&plcmntcat=&p1=&p2=&aceid=&position=1t2&gclid=Cj0KCQjwwevLBRCGARIsAKnAJvcM23uQYDkbQgq5nHPovtiacaPEZHoY2_MBgVUNvF50jmzpyBBIBf8aAkbWEALw_wcB

      You can also source other head screws other than the Roberts head from indian manufacturers in bulk

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  14. Thanks. Avoid buying anything Chinese.

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