How very Italian

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#16 Post by **mangocrazy** » Wed Feb 19, 2014 10:28 pm

OK, that makes a lot more sense now.

Certainly metric fine threads do go down to 0.5mm pitch and lower, but that is on the smaller sizes (less than M6). I know that M12 fine is 1.0mm or 1.25mm (standard is 1.75mm), and a standard coarse thread for M22 is 2.5mm, so by that reckoning 1.25mm is fairly fine although not the finest available (M22 x 1.0).

Just checked through a metric thread fine pitch data sheet, and for everything from M12 up to M28 the finest thread pitch available is 1.0mm.

fatboy · #17 Post by **fatboy** » Thu Feb 20, 2014 7:37 pm

Jesus, Mango, I had no idea the thread pitch went as far as 2.5.
That must be almost like a file !
I did ask in my local fastener/ steel stock holder shop about a 22mm x 1.25 bolt....
When they stopped laughing, they said ' that would be specialist as the pitch versus size is ultra fine'
I had mistakenly believed 1.25 to 1.5 were standard, so I bow to your superior knowledge good sir !

#18 Post by **mangocrazy** » Thu Feb 20, 2014 8:42 pm

No worries...

I've been caught out so many times by thread pitches (especially the bewildering selection of metric fine threads) that I pay close attention these days. I even went as far as getting a 100 piece set of US Pro taps and dies, and find there are still some missing that I need!

It's a bloody minefield...

But you're right - a thread pitch of 2.5mm is really coarse. It all depends on the bolt/thread diameter, I guess. Standard pitch on an M6 bolt is 1.0mm - standard pitch on an M22 bolt is 2.5mm