I'm sure it's out there somewhere on www but I can't find it - what is the tapping drill size for a standard 18mm sparking plug thread?
TIA
NHH
plug tap drill size
Dec 20, 2008
5 Replies
Thanks. No I don't have anything 'neerenuf' then!
NHH
Mike.H. wrote:
An old tip to get the tapping size for metric thread is the size of the thread minus the pitch. It's not 100% accurate but is very close.
John
18-1.5=16.5mm - which ISTR (link's gone T.U.) is what the chart referred to above says! Good tip.
NHH
Thanks for re-sending link Mike - actual figure in the chart is 16.8mm so 16.5mm would probably be ok if you took it easy.
NHH
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