# Screw (or nail) size selection ?



## cellophane (Oct 6, 2009)

I have a novice question - with the huge array of fasteners available, how do you know which type is the correct one to use? Is there a chart that says if the wood (or metal etc) is X dimension use Y screw? Obviously if you need to screw or nail through 3 2xW members you need a longer fastener - but how is the diameter chosen correctly. 

in short - assuming all variables are the same, why would I use a #8 1" Screw versus a #6 1" Screw?


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## johnep (Apr 12, 2007)

screwfix.com has huge range of screws and their catalogue/site contains loads of advice.
johnep


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## cabinetman (Jul 5, 2007)

cellophane said:


> I have a novice question - with the huge array of fasteners available, how do you know which type is the correct one to use? Is there a chart that says if the wood (or metal etc) is X dimension use Y screw? Obviously if you need to screw or nail through 3 2xW members you need a longer fastener - but how is the diameter chosen correctly.
> 
> in short - assuming all variables are the same, why would I use a #8 1" Screw versus a #6 1" Screw?



The lengths of both screws and nails should be at least more than half the length of the fastening distance. IOW, the fastener should be half to two thirds into the recipient piece when the head is fully seated.

For screw size its an axial issue of the stresses for the size and length of the fastening and the thickness of the pieces, IMO. THIS CHART shows and explains sizes and lengths. A proper countersunk pilot hole along with a fastener with an effective thread design, and properly driven is the ideal arrangement.


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## cellophane (Oct 6, 2009)

thanks =)


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