countersink bit size for screws?

chezybezy

hello
i am hoping someone can help as i am rather confused.
i am about to lay some chipboard flooring in the loft and am wanting to countersink the screw heads but i can not seem to work out which size countersink bit to get.

i am thinking of using the 4mm screws - which i believe have a ~6mm head? and i think these are refereed to as m4 x length screws? any clarification on these 'terms / understanding' would be greatly appreciated if i am incorrect.

i also plan on doing the same with some squeaky floorboards.

i am unsure which countersink bit to 'search' for, any i look at do not seem to identify with the information i have.

if anyone needs links to the screws i have / ordering just let me know.
thank you

billymadbiker

The size of the countersink will be the overall size of it.

So you need one just slightly bigger than the size of the head of the screw.

Or use a bigger countersink and don't push it in more than you need to

billymadbiker

Or just use chip board screws.
Most of those have little ridges under the heads of the screws and they will countersink themselves in.

hd216

I just boarded out my loft and I didn't bother countersinking as the screws I used (Wickes Ultra Gold Wood Screw) will happily sink themselves in the chipboard as they are self countersinking. Just make sure to drill a pilot hole about 2 mm smaller than the diameter of the screw to stop the board from splitting when screwing them down.

missile

You could buy a countersink drill

Le_Kirk

Try this handy guide to wood screw sizes. As advised above, just buy a "standard" wood countersink bit and only drill down far enough to take just more than the size of head of the screw.

chezybezy

billymadbiker wrote: »

snip

hd216 wrote: »

snip .

missile wrote: »

snip

Le_Kirk wrote: »

snip

brilliant, thank you very much.
for some reason i hadn't thought it would be ok to use a slightly larger one!
i am tempted by the self countersinking screws - i might have to switch to them in the future! its just the age of this property and the wood here i am very concerned r.e. splitting / the hardness of the wood from being 'here' so long. and while for the loft job it would only be the bottom of the screw and not the top i still worry. when i get some pics i might put up a post on here - it is rather low!

i am still a bit confused when i was looking at things like this:
https://www.amazon.co.uk/Makita-P-51954-Pieces-Countersink-Multicolour/dp/B00PKG9Y56/

i think i am just confusing myself, i might just grab that one missile linked in my next order, anyone know if this is adjustable in 'height'? and the 9.5mm wont be too large for my needs? it just seems a little larger than my requirements?

thank you very much

Tom99

Use one of these for £1.29.

https://www.screwfix.com/p/countersink-12-x-38mm/9656v

It helps if you have two drills in the loft as that way you don't have to keep changing bits.

AndyMc.....

Tom99 wrote: »

Use one of these for £1.29.

https://www.screwfix.com/p/countersink-12-x-38mm/9656v

It helps if you have two drills in the loft as that way you don't have to keep changing bits.

But with that you’ll need three drills unless you’re using a screwdriver.

pmartin86

Well !!!!!! me...I never even realised there were different sizes of countersync bits, ive always used one size and only pressed as hard as needed, learn something new every day!

bris

The screws countersink themselves, no need to use anything else.