Ordering the same size (metric) woodscrews as the ones I have

[Expoten]

In the past when I picked up an ordinary woodscrew, I used to look at the head diameter and could usually guess what "number" it was. If I had to measure it then the head diameter in millimetres seemed to give me that "number" value.

Now I want to get some replacment screws by ordering online but it's all metric and seems a bit of a muddle to me.

Is the head size of a woodscrew still a good guide to the shaft diameter? The illustrations I've seen suggest it might not be. If I can't use the head size to determine the shaft diameter then what measurements should I use?

In the end I want to order some (metric sized) woodscrews similar to the ones I have (the older ones are probably imperial). How can I do this? I can take accurate measurements ofmy woodscrews using calipers but how do I translate that into what I can order?

[meow2222]

Screws now come dimensioned in 2 ways:

- shaft diameter

- number Just buy them specced as shaft diameter. If eg you wanted a 3.5mm shaft, you buy 3.5mm x 50mm etc. See screwfix.com

NT

[SonomaProducts.com]

Scroll down on this page to the lower chart

will see decimal head sizes.

Then you can also look at my favorite chart at

This is the one I have taped to my toolbox. You can see for instance that a #2 shows an 11/64 head bore size. Divide 11 by 64 and you get .171875. The fuller chart shows head size as .172. So you can just use the wood magazine chart.

Not sure this gives you what you want but thought it might help answer some questions.

[cselby]

CAn you repost this URL. Doesn't seem to work.

P

[Andy Burns]

It works fine, is your Acrobat reader OK? The document doesn't require a recent version.

[Clive George]

[cselby]

Got it. That damn trailing "." did me in.

thanx P

[Expoten]

Thanks for the info. So the head diameter doesn't come into it.

Have I been wrong all these years for using the head diameter to get the screw size (or "number")?

In fact, I still want to use the size of the head in choosing a woodscrew because I find I often have to consider it on account of what is on the surface. IYSWIM.

Is there a chart which shows the head diameter for given shaft sizes of metric woodscrews?

[Expoten]

They're both good charts. Thank you.

can't quite work out what the first chart means by: "Basic Dec(imal) Size"

The charts both use US sizes and unfortunately I have found that the main metric sizes are sometimes not even all that close to the old inch sizes.

It would be really great to have similar charts in metric. Does anyone know if they exist?

[Tom Veatch]

The unthreaded shank size. Minimum size for a clearance hole. Given by the formula 0.060 + 0.013 x "Number".

#0 = 0.060 #1 = 0.073 #6 = 0.133 #8 = 0.164 #10 = 0.190 #14 = 0.242 etc.

Tom Veatch Wichita, KS USA

[PeterC]

Don't know if of any use, but Screwfix has a chart, e. g. the 2 links on this page:

[PeterC]

IME the head varies with source - I have screws of the same nominal size but with 1mm or so difference in head dia. Can be useful at times.