Use the Right Bit for Your Screw




Spending anytime in a makerspace when building is going on you will always hear power drills whirring away. More often than not you will hear a mixture of the drill clutches and bits slipping in the screw heads. My father taught me how to choose the right bit for the screw you are using. This knowledge is invaluable but does not seem to have been passed down the generations.

I am sharing this knowledge so that all makers can benefit from easy screwing, less damage to the crew heads and bits.


Step 1: Understand Your Screws

A screw has many features that go unnoticed. They have a head, which is the socket that your bit engages with.

There are many types of socket, in the photos you will see square, torsion, posidrive, phillips and slot head.

Each head type has different features and is used by different manufacture depending upon the intended use of the screw. I will not cover these in this ible, but will follow up with a more in depth look at your screws.

There are measurements for length, width, the amount of cutting faces, sharp tip, coatings and many more.

Step 2: Which Bit for Which Screw?

It is very normal to buy screw driver bits in a set. It is worth noting the price and brand name, the set in the photo is missing some key sizes that I did not notice when I bought them. They were of course cheap and will do a number of jobs but they are not quality. For example I would not use them with a strong torque driver.

I recommend going for a full set, high quality, designer for all power tools, including impact driver. These insure you have a quality metal that will last.

Step 3: Choosing Your Bit

For the layman that just wants to screw, look at your screw head. Find the shape that matches your pattern, work your way down from the largest size until the bit just fits. Do not make the mistake of choosing a bit that just fits, it may be too small and will slip causing damage to the screw head.

For the more initiated your screw box will have the size of bit detailed on it, your bits should have the size engraved. Just choose the matching bit and all is golden.

Remember if your bit is slipping, ensure you have the right one. Stop driving your screw and correct the problem. If in doubt ask someone, screws are not designed to slip.

Happy screwing.



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    8 Discussions


    3 years ago

    It's good to distinguish between Philips (bottom left of the four) and Posidriv screws (top right of the four above). Many people just say "cross-point" and think that they're the same, but they aren't. Getting the right driver for the screw will make your screwdrivers last longer and make it less likely that you will chew up screw heads. Posidrive are better than Philips IMO as they don't "cam out" as much. I don't think that Philips drivers are designed to cam out when high torque levels are reached, it's just a flaw in the design.


    3 years ago

    The square is called Robertson.


    If I may, I'd like to comment on "screws are not designed to slip". Philips head drivers are designed to cam out of the screw when too much torque is applied. This can prevent over-tightening the screw and/or damaging the screw head. I know this was just a basic overview (and a very good one), but not everybody knows that.

    1 reply

    Reply 3 years ago

    And if you over tighten, The bit tears down the screw, And you can't remove it...


    3 years ago on Introduction

    I think when he said just fits would be the same type of bit but not the correct size.Kind of like using a #1 phillips bit in a size #3 phillips head.There are 24 different sized phillips head screws but only 5 sized phillips bits or drivers.I am new so I am not sure if I can post web sites but I found 2 way back that have been very helpful.Sorry if I am not permitted to but here they are.Actually the covers many topics and makes good reading .Hope these help even a little bit.Good luck with those projects.


    3 years ago on Introduction

    You wrote, "work your way down from the largest size until the bit just fits. Do not make the mistake of choosing a bit that just fits," By the second "just fits", did you mean "simply fits the shape of the screw head but is not snug"?


    3 years ago on Step 2

    Buy cheap ,Buy twice .Always buy quality tek bits,they will last . Cheap ones just crack and disintegrate most often.


    3 years ago

    Using the right bit really makes your life much easier!

    To add a tip (pun intended) : throw away damaged bits.. they will be an annoyance every time you use them again!

    I like your suggestion trying from large to small to find the right bit... never thought of that. I'll be using that from now on :)