Dual grade bolts mystery 1

[MintJulep]

I'm looking at a picture of some bolts that are physically SAE size. 5/8" UNC threads, inch-size wrench fits perfectly.

The heads are marked with three radial dashes, indicating SAE Grade 5. BUT, the head is also marked "8.8", as a metric class 8.8 bolt would be.

The "8.8" is in the sector between two of the radial dashes.

In one of the other sectors is "UNC".

In the third sector are three characters. The first is a capital Lambda. The second is a "P" and and "L" superimposed, and the third is an "O".

Anyone got a clue what I might have here?

 

[deanc]

Sure.

Some of that new Pacfic Rim stuff. "We call it whatever you want".

http://ts.nist.gov/WeightsAndMeasures/fqa.cfm

Check the Insignia Register

 

[sdz]

Sounds like you are looking at a grade 8.8 high strength structural bolt, probably metric.

 

[yates]

This is not pacific rim stuff. The bolt is of European manufacture. P and L superimposed is the trademark of 'Paul Lefevre' later Blanc Aero, now Lisi (see fastener quality act trade mark listings and MIL-HDBK 57) It is a hi-strength aerospace bolt class 8.8 but with UNC thread.

 

[MintJulep]

Not Lisi.

 

[TVP]

yates is correct that the P & L superimposed together form the logo that is registered to Lisi/Blanc Aero. I do not recognize the capital lambda and O as meaningful head markings.

 

[MintJulep]

Found the maker:

A. Agrati of Milan, Italy.


So the marking is "oav".

Interestingly, "Down" for the "oav" mark is the center of the head, while "down for the "UNC" marking is one of the head flats.

 

[CoryPad]

Upside down - that is hilarious.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MintJulep]

Still doesn't explain why a bolt with UNC threads has both a metric and UNC grade identification.

 

[CoryPad]

I agree - that is non-standard.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[hokie66]

Italians always were helpful people. I guess the manufacturer is just trying to put as much information on the bolt head as possible. SAE 5 and 8.8 are about the same strength steel. What makes this poor practice is that in the globalised environment we live in, the sizes will surely get mixed up somewhere.

 

[swall]

MintJulep--I was just curious. How well does a 16mm wrench fit the hex head?

 

[MintJulep]

Swall,

Nice thought, but wrong size.

Heads for a 7/16" bolt (5/8 across flats) and an M10 bolt (16 mm across flats) do overlap.

 

[deanc]

http://www.agrati.com/uk/gamma/unificati/index.htm

Go to....Bolts....Hex Head Cap Screws, Thd UNC

Star for you MintJulep. These guys had something I had been looking for.