what is more common, a M12 x 1.25 or M12 x 1.5 bolt ?

[i_r_machinist]

I have some tooling to make for Siemens for generator work. I have several prints that call for "M12 threaded hole". I called one of their engineers for clarity. Can't get an answer. These holes are for lifting brackets, so I assume they will use whatever bolt is handiest, so....
What is more common, a M12 x 1.25 or M12 x 1.5 bolt ?
thanks
i_r_

 

[iwananew10K]

Take with a grain but I thought 1.75 was standard unless otherwise specified.

Glad to be corrected.

 

[michiganbuck]

Gordon always said.. Unstated means standard.
https://www.boltdepot.com/fastener-information/measuring/metric-thread-pitch.aspx

Here in the US I still like it stated..

 

[Benta]

I expect that a hole for a lifting bracket would use standard M12 which is 1.75 mm pitch. I see no reason to use a fine thread for that purpose.
Also, when a drawing only states M12, it's standard pitch, otherwise it would be explicitly stated on the drawing.

Benta.

 

[EPAIII]

Well, M12 is confusing. M12 x 1.75 is the coarse thread size. M12 x 1.5 is the fine thread size. And M12 x 1.25 is the extra fine. I have no real experience with any number of these, but McMaster seems to stock more of the M12 x 1.75, coarse thread so, with no other information, I would go by that one.

 

[billmac]

An M12 threaded hole if described in exactly that way means that it is a standard M12 thread, which is 1.75.

If any other pitch is required it must be stated. If it is not stated it is standard.

This question arises very frequently on this website, it would almost qualify for a sticky note.

 

[Lambert]

Over here in Metricland if the spec is just type and nominal size (i.e. metric 12 mm a.k.a bog standard M12) it`s understood to be from the metric coarse range.

As such your M12 has a pitch of 1,75 mm.

ANY German (or other European for that matter) engineer just specifying M12 and expecting anything else then M12 x 1,75 from the metric coarse range deserves a kick in the bollocks.

 

[i_r_machinist]

I believe the engineer is from Kenya, working for Germans.
Thanks for all the replies!
i_r_machinist

 

[John Garner]

I'd be absolutely astonished if any major industrial company operating in the US or Europe would use "whatever's handy" hardware for lifting. The Swivel Hoist Ring (SHR) that American Drill Bushing developed when they were still in the LA area is probably today's de-facto standard "lifting eye" for most applications, and ADB-pattern SHRs are now made by a number of different companies.

See the attached link -- one maker's SHR data sheet, but other-maker data sheets are easy to find on the web -- and note that the SHRs using M12 mounting screws have an M12 x 1.75 screw built in.

http://www.lift-it.com/actek®-metric-swivel-hoist-ring

 

[juergenwt]

Ever since ANSI ok'd the listing of a pitch for Standard threads we are (in USA) struggling with the problem they created. Anywhere else in the world if it says M12 - no questions. If no thread pitch is listed than it is ALWAYS coarse. There are a few cases where a fine thread is needed - than it would be listed as in M12 x 1.5.

When we first went metric I bought a series of fine pitch taps for the tool room. Have not used one in over 20 years. So save your money.

 

[juergenwt]

Well, M12 is confusing. M12 x 1.75 is the coarse thread size. M12 x 1.5 is the fine thread size. And M12 x 1.25 is the extra fine. I have no real experience with any number of these, but McMaster seems to stock more of the M12 x 1.75, coarse thread so, with no other information, I would go by that one.

McMasters will be stuck with a lot of metric fine taps and dies. Metric threads are designed so coarse can be used 95% of the time. If you see an American print with all the pitches listed than you have to check whether you are dealing with coarse, fine or extra fine. Many times the designer has no idea why he asked for that and it would require someone to stock all types of taps, dies and screws.

 

[John Garner]

I freely admit to having a mindset that doesn't favor by-reference incorporation of "source documents" into engineering drawings, but I really am having trouble understanding why explicitly stating the pitch of standard / coarse M-series screwthread in a drawing would confuse or confound a European-trained machinist, even though the European convention is to imply that screwthread's pitch.

In prior discussions here, it's been stated that the European-trained machinist would either 1) know the standard / coarse diameter x pitch combinations, making the drawing citation unnecessary, or 2) if tapping or die-cutting a thread, would use the coarsest-pitch tap or die of the requisite diameter.

Over the years, I've used a fair number of European-made taps and dies, but the vast majority of them were sold in the US market, and I'm open to the possibility that the M(Diameter) x (Pitch) markings on the shanks of the standard / coarse pitch tools were playing to the US convention. If not, though, and the M(Diameter) x (Pitch) markings on standard / coarse pitch taps and dies are "the usual" in Europe, shouldn't those markings confuse those machinists who are confused by drawings specifying M(Diameter) x (Pitch) for standard / coarse threads?

John

 

[michiganbuck]

It would waste space on the print and a few seconds in the drafting room each time it was done. Far better for people in SAE land to wonder and make a phone call. Interpreter service could be found if needed.

Anyone in metric land should have a major Donny Brook and go to the front office with seeing a standard metric thread listed with pitch. Or they should call the US engineer/ draftsman and ask what do you mean?

 

[Garwood]

1.75 is standard. 1.25 pitch is the standard for M12 fine thread bolts. 1.5 pitch is the standard for M12 fluid connectors like Banjo bolts, etc.

M12 1.5 pitch is rarely used for bolts.

Both 1.75 and 1.25 pitch M12 are very common.

 

[CalG]

A big issue here in the Contrary States, (non metric) Is that "common" and "standard" are two entirely different things.

OUR "common" experience is often limited to automotive application of metric fasteners. In that industry, Standard sizes seem to almost NEVER pop up.
Fasteners are all too often optimized for either the specific application, or worse, for installation ease.

So though there may be a "standard" as a coarse threaded 12 mm fastener, If I go to my "metric junk bucket", I bet there are fewer than 10% in the coarse configuration. So not very common.

Blame it on the car makers! ;-)

 

[Zonko]

John Garner
A normal European tap does indeed only read M12 etc.
At least the pre globalization ones. Not sure if newer ones are different.....

Putting stuff like M12x1.75 on a print is, imho, a bad idea because seeing a pitch at the side of a thread specc sends the European brain into an automatic frenzy " Do we have this tap ? " only to realize a split second later " D'oh, thats M12, we got a whole lot of those"


May seem confusing to Americans, but believe me, it confuses the HECK outta me to see you American people throw around all sorts of weirdo thread speccs ALL the time.
Y'know, stuff like 8-30. Just what ?

http://www.midstatesbolt.com/technical-tap-drill-sizes.php

Just NO. What the heck.


However, there is one advantage to listing the pitches: nominal od minus pitch is an acceptable drill diameter.

 

[Oldwrench]

Coarse pitch is for tapped holes in castings, and structural bolts.
Fine pitch is for applications that must resist loosening from vibration...like cars and airplanes

That's common sense, it doesn't matter which measurement standard you use.

 

[juergenwt]

Metric pitches (standard coarse)are designed to save money by cutting down on the use of all types of fine and extra fine pitches as is common in the US. Metric coarse pitches fall in between US coarse and fine and are to be uses most of the time. Metric fine is for special applications only!!. Do not stock metric fine taps, dies, bolts and nuts. You will just have them forever. If for some reason you should need one, than they are only a phone call away. Engineers and designers in the US need to get real and forget about using metric fine thread. (Very special occasions only).
The problem with putting a pitch on the coarse thread is, that when you see a pitch listed like on M12 x 1.75 you now start to wonder. Is this a coarse standard? Is there a coarser pitch available? Now the print goes to the shop where the craftsman will now look for the marking on the tap or die. Do we have nuts? Do we have bolts, do we have a die or tap. All wasted time and money. You just want to stand there and scream: Yes!!! It is the only one we have and YES it is the only screw we have in stock. Just stick with standard coarse and leave the specials for special occasions only. I have seen engineers who after 20 years of using prints with just M12 or so listed still on occasions have to ask - what pitch? Are we in the US so dense that we can not comprehend the worldwide usage of not listing the pitch on standard coarse? Ansi knows it screwed up - but we had to Americanize a system that is used worldwide and every time someone in the US asks for a clarification for M12, M10, M8 or so, somewhere somebody is shaking his head - what part of M12, M10, M8 don't they understand.

 

[Pete F]

M12 means metric coarse. M12 x yyy means something other than metric coarse. It would be stupid and pointless to call out the pitch on a metric coarse fastener, it has already been specified by its omission. Likewise nobody puts RH after the callout, not even in America! The omission of thread direction specifies the thread as right hand. If it's left handed only then will it be called out. The use of Mxxx simplifies the whole process, as it removes the possibility of confusing thread pitches and neatens up the drawing. I'm really aghast that anyone could find themselves confused by this. Download a table, very commonly available on the internet, of metric coarse threads, and you will always have your answer to what the thread pitch is when you see Mxxx. Whether that is the "most common" in your particular field will depend on that that field is, but has no relevance to the callout.

 

[John Garner]

What I'm hearing is that metrificated machinists know the standard (coarse) M(diameter) x (Pitch) combinations so well that citing the (Pitch) on the drawing is simply a waste of time and effort, but not well enough that you recognize it instantaneously as the usual combination.

Ok, now a question for the imperialist machinists: Which citation would you rather see on a drawing, 1) 1/4-20 UNC, 2) 1/4-20 UN, or 1/4 UNC? Since I don't earn my paycheck as a machinist, I'll only say that I do have a preference, but recognize all three as unambiguous ways to specify threadform, Major Diameter, and Pitch.

And a sister question for the metrificated machinists: There are some specific-purpose, international-standard screwthreads that were essentially picked from the Unified threadform standard Diameter and Pitch pairs -- camera a survey-instrument tripod attachment threads come to mind. How would you recommend that such threads be specified on an otherwise-fully-metric drawing?

John