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Threaded hole specification

Posted: 5 Feb 2020, 10:51am
by mattheus
thread gurus (or better still, machinists), tell me everything you can from the following spec (on a drawing):

7-TAP M3x0.5-6H THRO'


I'm listening ...

Re: Threaded hole specification

Posted: 5 Feb 2020, 10:58am
by alexnharvey
7 don't know, possibly the item reference number on the drawing.
TAP a tapped threaded hole
M3 diameter, 3mm.
0.5 mm, thread pitch.
6H tolerance of the work, 6H is average quality of fit between the threaded parts.
Thro, abbreviation of through, as in the hole penetrates the part rather than being 'blind'

Re: Threaded hole specification

Posted: 5 Feb 2020, 2:55pm
by Brucey
sounds reasonable to me.

FWIW proper drawings are done to standards. It should say on the dwg what standard it is done to, and then the meaning should be unequivocal, provided you use the standard.

cheers

Re: Threaded hole specification

Posted: 5 Feb 2020, 8:08pm
by mattheus
thanks chaps!

Re: Threaded hole specification

Posted: 7 Feb 2020, 5:00pm
by hayers
The "7" might also be the number of holes - would more commonly be shown as "7 x tap m3..." or "ta m3... 7 places" but I've seen lots of variations. Used to avoid cluttering the drawing labelling every hole.

Of course if there's not 7 holes jn the OP's part this isn't the case here...

Re: Threaded hole specification

Posted: 9 Feb 2020, 9:01am
by mattheus
hayers wrote:The "7" might also be the number of holes - would more commonly be shown as "7 x tap m3..." or "ta m3... 7 places" but I've seen lots of variations. Used to avoid cluttering the drawing labelling every hole.

Of course if there's not 7 holes jn the OP's part this isn't the case here...

That is indeed correct for the OP's part - it has 7 holes :)