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Anonymous Poster

thread specification

02/23/2011 5:15 AM

Hi,

A hole with internal threading is specified as M8x1

does 8 represent the maximum diameter or minimum diameter (in mm).?
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AussieBob
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#1

Re: thread specification

02/23/2011 5:38 AM

This may help you
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Tornado
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#2

Re: thread specification

02/23/2011 6:53 AM

M8 would specify a maximum (outer) diameter close to 8 mm, but you need to consult a thread standard to get more exact. (I'm not sure that M8x1 would be the same as M8x1.25, which seems to be the "normal" combination.)

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34point5
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#3

Re: thread specification

02/23/2011 6:56 AM

8 would represent the screw O.D. - as it does in say 5/16th imperial.

1mm is the 'fine' series pitch, so the hole to be tapped would be drilled 7.00mm

Very few people use 'fine series' metric - it is truly 'fine' - it's for real precision work and 0.01 tolerances.

However M8 (as seen in the table above) is commonly 1.25 pitch - meaning the hole would be drilled 6.75 mm dia. (Likely in production 6.8)

(numbers from ZEUS precision - maybe you should buy one)

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Anonymous Poster
#4

Re: thread specification

02/23/2011 10:17 AM

Nominal Dia minus the pitch equals the tapping drill size.
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