Metric threads - all the same or not?

[coldsummer]

Having got all my powder coated parts back I started cleaning out some of the packing in the threaded parts and I want to run a tap through them just to give them a final clean but I'm not sure if all metric threads are the same pitch. The reason I ask is that I've noticed an ebay nut seller (!) states the 70's Jap bikes have a fine thread, or something like that, and I really don't want to f*** up the threads by running the wrong tap through. I have a standard metric tap and die kit.

Any thoughts??

[Steve Cooke]

Go careful as there are a mixture of thread pitches used throughout, quite a few being metric fine which your standard Tap/Die set probably doesn't have.

[GUYZED]

Bottom yoke 12mm bolts are 1.25 fine pitch.

[wilsonsjw11]

Simon
As a rule of thumb anything above M8 is 1.25 pitch M6=1.0 M8=1.0/1,25
But before running any tap through any hole match the tap up against the proposed bolt for that hole ie lay it along side each other and make sure the pitches go in to each other.
Regards
Steve

[tlc]

Maybe a typo there Steve.

I can`t think of any fine thread M8 threads but commonly M6 are 1.00mm, M8 are 1.25 and M10 are 1.25mm and 1.50mm.

Go to your local quality tool specialist and buy a set of 3 taps of each size. Those being taper, second and finishing taps. These will be a sound investment and will last a lifetime.



4 = 0.7
5 = 0.8
6 = 1
7 = 1
8 = 1.25 or 1
10= 1.5 or 1.25 or 1
12= 1.75 or 1.5 or 1.25

[wilsonsjw11]

Chris well spotted,MUST OF BEEN THE TIME OF DAY
Whats the pitch on the M8 studs for the front axle clamps while were on the subject?

[Big Fluff]

If you know what bolt/screw goes where, and you're either fitting new or have spares, then the best way would be to cut a sharp groove lengthways along the threads of the old bolts etc. and use that as a thread cleaner.
Will.

[coldsummer]

Thanks, as always, for the helpful replies guys. I'll certainly tread very carefully with this.

[Magnum1]

I bought one of these;
http://cgi.ebay.co.uk/Metric-Whitworth- ... 19b833ab74
Rod

[Taffus]

Maybe a typo there Steve.

I can`t think of any fine thread M8 threads but commonly M6 are 1.00mm, M8 are 1.25 and M10 are 1.25mm and 1.50mm.

Go to your local quality tool specialist and buy a set of 3 taps of each size. Those being taper, second and finishing taps. These will be a sound investment and will last a lifetime.



4 = 0.7
5 = 0.8
6 = 1
7 = 1
8 = 1.25 or 1
10= 1.5 or 1.25 or 1
12= 1.75 or 1.5 or 1.25

TLC you're our very own "Bernie the Bolt"

[nigel bessant]

Thanks, as always, for the helpful replies guys. I'll certainly tread very carefully with this.

Or did you mean to say "Thread very carefully"
God I'm good!

[Taffus]

Thanks, as always, for the helpful replies guys. I'll certainly tread very carefully with this.

Or did you mean to say "Thread very carefully"
God I'm good!

yes, you "pitched" it just right for whitworths

[ZedHead]

Get a THREAD PITCH GAUGE like this one.

http://cgi.ebay.co.uk/BSW-IMPERIAL-METR ... 4837004ddb

[nigel bessant]

Thanks, as always, for the helpful replies guys. I'll certainly tread very carefully with this.

Or did you mean to say "Thread very carefully"
God I'm good!

yes, you "pitched" it just right for whitworths

I can't respond to that for fear of being dubbed the village idiot! But...If I was to respond I'd make a quip regarding boxed dried fruits associated with the age old art of cake making and the like.

[nigel bessant]

Might I suggest that you get hold of a "Zeus" book. It's a small booklet that gives loads of information on, apart from other things, thread information, ie pitch, depth, form, as well as tapping drill sizes and reccommended clearance hole sizes. It covers all thread forms and you never know when you might need it for other threads, like Big F*ck Off V8 Yanks! The other thing that is useful is a good quality thread pitch guage. not the cheap ones as these are usually a fettled stamping. I bought my Zeus book at the young age of 17 as a silly little apprentice. It's lasted 33 years and smells of cutting oil!!