Matching size of drill bit used to screw size?

martin57

Hi folks,

Bought a cheap hammer drill at argos some time ago and used it to put up some curtain rails as well as a few other things. Have been advised on another thread that it would have been better to have had a sds drill but as I wouldn't be using it that often though it a bit of an expensive outlay.

To be honest overall I have found getting used to the drill difficult, great difficulty in getting into wall especially over windows (probably the reason for the suggestions for an sds drill) At times the drilled holes have been too large, thank god for matches !

When selecting a drill bit do I have to select a masonary one the same diameter as the screw, and likewise do I select a wall plug the same diameter and length as the screw?

Overall I'm a bit disapointed in my ability to do this simple job which no doubt others could literly do with their eyes closed.

Any further pointers really appreciated.

martin57

DVardysShadow

You select screw, drill bit and plug to be the same nominal size - No8, No10 etc. This does not mean they are the same diameter, but that [generally] they work correctly for each other.

mchale

Generally for most things in a house I use a 5mm drill bit with yellow wall plug and size 6 screw, that way if you make a mistake you can always go next size up, and drill the hole about 4mm longer than the screw, you don't need a huge screw (ie size 10) to hang a mirror, picture etc, the main thing to get is good quality drill bits.

vaio

the plug is the key and will be marked with the right size drill to use for the size screw you re using

eg the red ones we use in work need 5.5 drill for size 6 & 8 screws and 6.5mm for 10 & 12 screws

tony6403

When drilling over windows , bear in mind that there could be a steel lintel supporting the structure above the window.
If you have concrete lintels these can contain steel reinforcement which might give you some problems.

wallbash

eg the red ones we use in work need 5.5 drill for size 6 & 8 screws and 6.5mm for 10 & 12 screws

I'm lazy , so I just reach for the red ones , the more popular packs ( rawplugs ) have a handy guide on the throw away section .