No 4 & No5 Bolt Heads (Update)

[Alan de Enfield]

As many of you will remember I have been compiling a spreadsheet of bolt head sizes for a few years now, and, now having the dimensions for 220 bolt heads I thought it was time for an update.

As you will see (and has been stated on numerous occasions) it is no use at all simply saying "I need a Number 3 bolt head" when (for example) a 0.632" up to 0.636" bolt head can be a number 0, a number 1, a number 2 or a number 3.

Tradition has it that the bolt head "numbers" fall within the following dimensions :
0 - .620 to .625 in.
1 - .625 to .630 in.
2 - .630 to .635 in.
3 - .635 to .640 in.

I hope you can see from the spreadsheet that this is not necessarily correct.

Note : I use the term "NUMBER" and not "SIZE".

Disclaimer - these bolt heads have been measured by several people using different measuring 'tools'. There is no way that these statistics would be taken as 'accurate' for QC purposes but I believe they show enough guidelines for us to be very careful when we are buying a 'new' bolt head.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.