Are There ANY SAE Thread Standards or Specifications?

[EPAIII]

References to possible SAE thread standards have come up many times. Another old thread that was recently resurrected started with a post that asked if a thread could possibly be an SAE standard. (It was actually an UNC.)

I have seen other references to possible SAE threads on this and other boards. I have asked before in various threads (questions) on this and other board if there actually are any SAE standards for threads. I guess that should be for machine screw or bolt threads. As far as I know, the SAE does not have any machine screw thread specifications and no one has produced a single reference to one. Yes, they do have many specifications for machine and other types of screws. But those screw specifications all seem to just refer to the UNC, UNF, or NS thread forms that are actually specified by ASME/ANSI, NOT by the SAE. Screw specifications and thread specifications seem to be TWO entirely different things and even Machinery Handbook handles them as such, using two different chapters of the book for them with little material in the cross-over.

So I am asking, does the SAE actually specify any machine screw threads? Or do they just refer to the ASME/ANSI, DIN, and other standards for the thread form on all their fasteners?

I can not afford to pay the SAE's prices for official access to their standards documents. So I must ask if someone who does have such access can point to any threads that they do actually specify. And to the SAE document that contains the specification.

 

[johnoder]

I have the handbooks from '38 and '43 - full of specifications

 

[4GSR]

The Federal H28 thread standards has some verbiage in the subject. Been a few years since I studied the standard. I do have the latest copy of the standard, I'll look if I get a chance. Need to look for some other things in that standard while I'm at it. The ASTM-ANSI/ISO standards is the standard today an I cannot afford to buy a copy of that standard.

 

[L Vanice]

SAE and ASME are both over 100 years old, so they have had plenty of time to create, revise and abandon thread or fastener standards. Here is a page from the 1914 American Machinists' Handbook.



You can see that the SAE threads are fine, what we call UNF today. The place I worked always had up to date copies of the SAE Handbook, the complete list of standards, but I never needed to look up the thread or fastener section. As was mentioned, those handbooks are expensive, so few people have copies. But maybe libraries do.

Larry

 

[awander]

From the 1920 Pogress Report of the National Screw Thread Commission:

"...the coarse thread series being the present "United States Standard" threads, supplemented in the sizes below one-fourth inch by the standard established by the American Society of Mechanical Engineers (A. S. M. E.)
The fine thread series is composed chiefly of standards that have been found necessary and consists of sizes taken from the standards of the Society of Automotive Engineers (S. A. E.) , and the fine thread series of the American Society of Mechanical Engineers (A. S. M. E.)"

After the National Thread Standard was put into use, the S.A.E. used National threads, and so their standard became obsolete.

 

[tdmidget]

SAE standard threads no longer specified by the SAE. The SAE is the custodian for the UN thread standards and for extreme cost you may buy copies but that information is in the public domain, being developed by the U.S. government.

 

[EPAIII]

After reading the above responses I am even more confused. L Vanice shows a page from a 1914 American Machinist Handbook with diameters and thread pitches that came from the then SAE standard? So the SAE did develop one, fine thread standard. Was there a thread profile drawing that went with that table, or just the simple statements about the body diameter and fit of the nut (without perceptible shake). None of the numbers in the table would seem to be of the correct magnitude to specify a flat at the crest or a fill at the bottom of the thread. Were these just sharp, vee threads?

And tdmidget said, "SAE standard threads no longer specified by the SAE. The SAE is the custodian for the UN thread standards ...". If the SAE no longer specifies the threads, how can they be the custodian for the UN (Unified National?) thread standards? Is this a typographical error on his part? And if this information is available for free; pray tell, WHERE?

It would seem that any SAE thread standard would have to be over 100 years old and out of date by 70, 80, or even more years. I can see where the auto makers of those early days may have needed to create their own standards which were then brought together by an organization like the SAE. But does even a single thread specification survive to the present day in the SAE's standards?

Do I need to find a ME board to get answers to these questions?

 

[awander]

According to my 1914 Machinery's Handbook, the S.A.E. threads, and the U.S.S. threads, both used the Sellers or Franklin Institute thread form, which is essentially equal to the current UN thread form, except that the flats at the root and the crest are both the same size in the Sellers form.

So all the S.A.E. needed to specify was nominal diameter, and TPI.

The Handbook also states that, "The American Society of Mechanical Engineers has adopted a standard for machine screw threads, in which the basic form of thread is the same as that of the U. S. standard system, but in which certain definite limits are given both for screw and tap threads."

Again, I don't believe that the S.A.E. was involved at all in setting thread standards, after 1920-something when the National Thread Form was adopted as a standard.

I do agree that tdmidget is probably mistaken is stating that, "The SAE is the custodian for the UN thread standards ..."

 

[tdmidget]

According to my 1914 Machinery's Handbook, the S.A.E. threads, and the U.S.S. threads, both used the Sellers or Franklin Institute thread form, which is essentially equal to the current UN thread form, except that the flats at the root and the crest are both the same size in the Sellers form.

So all the S.A.E. needed to specify was nominal diameter, and TPI.

The Handbook also states that, "The American Society of Mechanical Engineers has adopted a standard for machine screw threads, in which the basic form of thread is the same as that of the U. S. standard system, but in which certain definite limits are given both for screw and tap threads."

Again, I don't believe that the S.A.E. was involved at all in setting thread standards, after 1920-something when the National Thread Form was adopted as a standard.

I do agree that tdmidget is probably mistaken is stating that, "The SAE is the custodian for the UN thread standards ..."

I agree too. It is currently controlled by ASME/ANSI. Unified Thread Standard - Wikipedia

 

[Bill D]

My 2000 Ford ranger uses all metric. bolts but... It seems like the heads are one size smaller then a standard metric bolt of the same thread size and pitch. I believe there are SAE washers which are smaller then standard outer diameter. Maybe because SAE is always metal to metal never wood?
Bill D.

SAE Flat Washers
SAE flat washers offer a tighter screw fit, are thinner and have a smaller outside diameter (OD) than comparably sized USS washers. Use hardened SAE flat washers with hex cap screw Grades 5 and 8.

 

[Tony Quiring]

Washers...

It seems the washers are noe loose fit.

Proper snug fit requires next size smaller.



Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[atex57]

Washers...

It seems the washers are noe loose fit.

Proper snug fit requires next size smaller.







Snug fit means the washer is interfering with the underhead fillet on a screw and is squeezed into the threads when using a nut. SAE is the "snug" fit.

Ed

 

[Bill D]

Snug fit means the washer is interfering with the underhead fillet on a screw and is squeezed into the threads when using a nut. SAE is the "snug" fit.

Ed[/QUOTE]

I suppose that may be on purpose to reduce vibration unscrewing the bolt. Lots of vibration in automobiles.
Bill D

 

[awander]

Snug fit means the washer is interfering with the underhead fillet on a screw and is squeezed into the threads when using a nut. SAE is the "snug" fit.

Ed

I suppose that may be on purpose to reduce vibration unscrewing the bolt. Lots of vibration in automobiles.
Bill D[/QUOTE]

The main purpose of a washer is to avoid putting pressure on the fillet, which would cause breakage.

 

[David Utidjian]

From what I have read (mainly Wikipedia and links) the "SAE thread standards" no longer exist. Not since the middle of the last century. Currently the thread form and series that SAE uses is based on the UTS (Unified Thread Standard) which is maintained my ASME/ANSI. According to Wikipedia:

Even today, over a half century since the UTS superseded the USS and SAE series, companies still sell hardware with designations such as "USS" and "SAE" to convey that it is of inch sizes as opposed to metric. Most of this hardware is in fact made to the UTS, but the labeling and cataloging terminology is not always precise.

Which may help explain some of the confusion.

But... before one gets too comfortable one might want to consider the fact that there is far more to a particular threaded fastener than simple thread form, thread series, and system of measurement. There is material, heat treatment, threading process (rolled, cut, cast...) finish, head form and size, head to body diameter fillet, body to thread transition, finished end of thread, torque specifications... to name a few. Without going in to too much detail one can browse the list of standards for fasteners that SAE does maintain.

My takeaway from this is that there is no one single set of standards for all the criteria that goes into the production of a given fastener but perhaps, at least, most standards do not conflict.

-DU-

 

[eaglemike]

My 2000 Ford ranger uses all metric. bolts but... It seems like the heads are one size smaller then a standard metric bolt of the same thread size and pitch. I believe there are SAE washers which are smaller then standard outer diameter. Maybe because SAE is always metal to metal never wood?
Bill D.

There are or were (I've not checked for a couple of years) different specifications used for some metric stuff in different areas of the world. I'm involved in the powersports business. Some companies use a 12mm hex nut for 8mm threads, and others 13mm. IIRC (generally speaking ) the Japanese have one version of metric, and Europe another. I'm sure someone will be along shortly and either tell me I'm wrong, or clarify. I have a bad a$$ headache right now and am functioning at a low level. My apologies for any errors.

 

[rickseeman]

I believe SAE was replaced by UNF in 1948 so any book before that should have what you need.

 

[Matt_Maguire]

The original SAE group adopted the US 60°V unified thread form with the odd duck of the bunch being the SAE 1-14tpi thread. That puppy lives on as UNS 1-14 in the world of off road heavy vehicles and is heavily used. If the former won’t make the grade then they’ll move to 1-1/8x12tpi usually (or more screws).

Make no mistake the mfg’s DO detail & modify/maintain internal fastener specs in house. Cat is 1E0500 for inch (31pg.) and 1E2650 for metric (16pg) for just the thread form and tolerance enumerations including interference fits for stud use in separate tables. For materials, HT etc. etc. each are covered in yet more 1E(fill in the #) specs... LOL

Good luck
Matt

 

[David Utidjian]

A few careers back (1980s) when I was working on cars. As I recall... Japanese cars used 8, 10, 12, 14, 17mm bolt head sizes on their hex head bolts. Germans used 10, 11, 13, 17mm bolt head sizes. Italians and French were mostly similar to German except for some oddities. Only place I would find 15mm or 18mm was on US made cars. On occasion I would get a very strange metric thread size on some special Italian car fasteners. For sensor connections some Japanese cars used BSP threads (British Standard Pipe)... mostly Nissan/Datsun. I don't think I ever found a 13mm sized bolt head on a Japanese car. I speculated that the Japanese were even more superstitious about number 13 than Western hemisphere people maight be.

-DU-