Screw sizes

[Baldhead]

I know it's been discussed on this site about how you measure the head of a screw to determine the size (or something along those lines) but I've searched and I can find it, can anyone tell me how it's done please. Also I have bought some 1" hinges without screws, how do I know what size to buy and where is the best place to get brass screws.

TIA

Baldhead

 

[Baldhead]

I've found it, another question though.

If the hole in the hinge is 3/16 (measured to the outside edge of the countersink) then am I correct in thinking that I need a #4 screw?

Baldhead

 

[Billy Flitch]

Correct if I remember it right from my apprenticeship time you turn the number into 32 nds then -2 and then that is the size you want. So 3/16 = 6/32 - 2 = 4/32 so the size of screw you want is a no 4 .

 

[Myfordman]

Generally head diameter = 2x Shank diameter.
Works for machine threaded screws too

 

[John15]

Hi Baldhead,

I bought some No.8 2" brass screws recently from Screwfix. They are quite expensive and very soft.

John

 

[Baldhead]

Thanks guys, John aren't all brass soft? or are the ones from Toolstation exceptionally soft? As they are for hinges I need countersunk heads and Toolstation don't do them as small as #4, so it's off to my local diy store or eBay.

Baldhead

 

[John15]

As far as I know all brass screws are soft. On a few I found they sheared off mostly when fixing for a second time. After a while I drove steel screws first to cut the thread in the timber to reduce the risk of them shearing and this worked well.
Cheers,
John

 

[Phil Pascoe]

Take a tiny shaving of brass off the hinge holes with a very sharp countersink then drive a steel screw in first, so the screws are very slightly below flush (if you want a perfect job) otherwise you'll run your finger over the finished job and feel a couple of rough edges. They never seem to seat quite correctly.