siggy Posted December 19, 2005 Share Posted December 19, 2005 got given some bolts for a job last night they had three radial marks on them which i believe stands for "Medium Carbon Steel, Quenched and Tempered" they are stamped 7 on the bolt head I can't find any info on that number anyone know of a website that explains the number figures many thanks Quote Link to comment Share on other sites More sharing options...
rtbarton Posted December 19, 2005 Share Posted December 19, 2005 got given some bolts for a job last night they had three radial marks on them which i believe stands for "Medium Carbon Steel, Quenched and Tempered" they are stamped 7 on the bolt head I can't find any info on that number anyone know of a website that explains the number figures many thanks Three radial marks are used to indicate high tensile on UNF bolts at least. Not sure what 7 means, imperial bolts usually have a letter. Do a Google on "bolt markings" you should find something. Quote Link to comment Share on other sites More sharing options...
siggy Posted December 19, 2005 Author Share Posted December 19, 2005 I have but found the marks but not numbers Quote Link to comment Share on other sites More sharing options...
LR90 Posted December 19, 2005 Share Posted December 19, 2005 I have but found the marksbut not numbers It's no an L is it? (thinks of the 710 joke) Quote Link to comment Share on other sites More sharing options...
Bush65 Posted December 19, 2005 Share Posted December 19, 2005 Three radial marks are used to designate SAE grade 5 (approx equiv to ISO class 8.8). But 7 does not fit with this! Japanese (JIS standards) mark the centre of bolt heads with a prominent number. With these 7 is commonly used and I have also seen 4, 9 and higher numbers used. An educated guess is that the number is similar to the ISO class (ie 7 may be just below class 8.8 and 9 between classes 8.8 and 10.9). Quote Link to comment Share on other sites More sharing options...
Lara Posted December 19, 2005 Share Posted December 19, 2005 Go and buy, "Nuts Bolts Fasteners and Plumbing" By Caroll Smith, Demon Tweaks sell it by mail order. It is the easiest and most diverse single source for fasteners and specs etc I have seen anywhere. Lara. Quote Link to comment Share on other sites More sharing options...
bishbosh Posted December 19, 2005 Share Posted December 19, 2005 As stated above, the three radial markes at 12, 4 & 8 o'clock mean grade 8.8. The number seven is odd - is it cast on the bolt or stamped on as an afterthought? For what it's worth, I'd swap them for some from a known source. In your business you don't want to get it wrong! Quote Link to comment Share on other sites More sharing options...
LR90 Posted December 19, 2005 Share Posted December 19, 2005 From http://motorcyclecruiser.com/tech/boltmark/ Not quite a 7 but seems the symbol is most likely a manufacturers trademark. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted December 20, 2005 Share Posted December 20, 2005 (edited) WTF is THAT ? A Tutenkarmon <sp> bolt ? Nige Edited December 20, 2005 by Hybrid_From_Hell Quote Link to comment Share on other sites More sharing options...
Lara Posted December 20, 2005 Share Posted December 20, 2005 (edited) Bloody hell, Gold Egyptian Bolts Must be High Tensile if they are that shinney Anyone knows, "the more you polish, the harder it gets" Lara. Edited December 20, 2005 by Lara Quote Link to comment Share on other sites More sharing options...
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