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  • Bolts

    First, does anyone know what this grade marking means on this 1/2" x 20 tpi bolt? I can't find it as a standard grade marking. I assume it is grade super strong of some sort.

    Second item: I bought some grade eight bolts the other day and found this in the bag. I thought there is supposed to be some sort of quality control on these things. No, I don't know where it was made but the place I buy them from does NOT sell crap tools of any sort, only top name brands since they supply the local sawmills and heavy equipment shops.

    If this sort of thing can get by it makes me wonder what gets through that isn't so obvious.

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  • #2
    That's a new one on me. Second bolt ,bottom pic looks like it's been in the junk yard for 40 yrs. Everything is just made too fast sometimes; quality suffers.


    • #3
      Evan, that marking normally designates a special alloy bolt. Bowman makes one that is marked similarly and is also designated L9. The center marking is probably the manufacturers mark or logo. Bowman fasteners have a triangle in the center.



      • #4
        No telling what the grade is on the first bolt,maybe something aircraft?

        We sell at work about $30k/yr in bolts,all different grades and alloys,you would not believe some of the "birth defects" I have seen.

        I've seen bolts that looked like they were threaded but had no helix.Ones with an accidental double or triple start.Nuts without threads,bolts without threads,washers without holes,washers with more than one hole and some pretty nasty plating jobs.

        But when most fastner boxes say things like"May have been made in one of the following counties"Followed by- USA,Japan,Germany,Mexico,China,India,Taiwan,Italy, Brazil,Spain,Bosnia,Paraguay,Phillipines,Mars,Jupi ter,you got to figure there will be a few duds in the box.

        Unless you buy certified fastners it's a crap shoot.
        I just need one more tool,just one!


        • #5
          could it be a grade 12 bolt? To test it drill a hole in it, if the drill bit glows red its grade 12.


          • #6
            Been there, probably broke it, doing that!
            I am not a lawyer, and never played one on TV!
            All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only


            • #7
              Its a timeing bolt. see there is 12 points of a clock on it, sort of like a sundial.


              • #8
                It's really a grade 8 setup so you can read 6 marks from any angle.


                • #9
                  A short, non-answer

                  Certain applications require threaded fasteners that must exceed the specifications found in grading standards. Heavy equipment, aerospace, and military applications are examples.

                  Manufacturers of those products produce their own fasteners, or have other firms produce the nuts and bolts to their strict specifications.

                  Those special, or one function fasteners, always far exceed the grading standards and are given markings, usually hash marks or raised numbers and symbols or even company logos, to identify and seperate them from the common bolts available on the market.

                  Your bolts with the 12 hash marks are that type of fastener - specially designed and produced for a specific product requiring a base material with additives and a processing treatment exceeding the highest common grade.

                  The industry, with some variations as to region and country, usually calls these bolts PBs - Proprietary Bolts, meaning they are made by or made for that company just for a specific use.

                  The 12 hash marks tells the user, or someone making a repair or an adjustment, or someone trying to buy a replacement, or a clerk in a supply center, that it is a special fastener.

                  All that doesn't really identify your bolt, but I am sure I have a few marked like that somewhere in my piles of stuff. I know I didn't purchase them for a specific use, they "accumulated" in the shop in "1's and 2's" over the years.
                  Today I will gladly share my experience and advice, for there no sweeter words than "I told you so."


                  • #10
                    Looks like a clockmakers bolt to me.
                    make a clock out of it.
                    I cut it twice, and it's still too short!


                    • #11
                      The one thing I know is that I bought these locally but can't remember for sure where. It was a long time ago when I was making some modifications to the 5th wheel hitch for my RV trailer and I wanted something strong to hold the hitch together. For a small town (less than 20k population) we have an extremely good selection of parts and materials locally because of the concentration of heavy equipment and industry related to logging, milling and mining. There are at least 8 - 10 fully equipped manual machine job shops in town and as many welding and fab shops.

                      Oh well, I was just curious.
                      Free software for calculating bolt circles and similar: Click Here


                      • #12
                        I worked heavy equipment and I had a truck full of those. They are made to a higher spec than a reg grade 8. I remember we were having problems with Good Year brake heads on a VME 275 C the old Clark 275C front end loader just a new owner and we were pulling brake heads like it was a nascar event. We were told by Good Year to replace the 1 inch dia bolts after 2 uses. They had the same markings. They were needed because of the extreme heat and stretching they were subject to.
                        Life Is Grand


                        • #13
                          years ago, we used some special marked application bolts called
                          "SuperTanium' and they had a 12 point marks , except they
                          also had an ellipse in the center of the bolt, with the marks radiating
                          out from it.
                          These bolts were slightly stronger than grade 8
                          they also had a light gold color.
                          They were NOT made from Titanium !
                          Grade 8 specifcation calls for 175K PSI tensile steel.
                          I think the ST's were 185K as I recall
                          Our application called for 750 deg F so we were really looking at hot strength
                          I went on the net and found this for you.
                          I did not read it, so cannot vouch for it, but it does discuss the bolts

                          My last company spent about 200k a year on bolts and I can relate
                          to all kinds of hooror stories on what the current market for bolts gets away with. When we buy bolts made outside the North American Continent, you can expect anything.
                          A quick example..American socket head setscrews(Allen)....must be grade 8 ( 175K PSI)(ANSI 1962 B standards)
                          but how many time have you had a cheap foriegn tool with crap set screws ?
                          Thats because the rest of the world (spell Metric) uses 3 grades for such fasteners..and you got it ! the cheap tools get the low grade socket head cap or set screws.

                          The surface finish is terrible, but that is not considered in the specs.
                          It's the steel that controls the grade
                          I personally despise the screws we get in the many shops.
                          I really doubt that the 12's you got are a SuperTanium bolt. i believe it is an imposter, because the originals were gorgeous bolts and cost 3 times a normal bolt.
                          If you want the best IMHO, get Unbrako's. they have the best steel control.
                          Camcar, Allen,and Hex? (old age memory shortfall) are a close second.
                          The rest are a total gamble......


                          • #14
                            I just went back and read my suggested URL.
                            it has already started !
                            Grade 8's are matched by Metric 12.9 DIN (mostly)(175K)
                            Grade 5 is 10.9 metric
                            Grade 3 is 8.9 etc

                            I see the Auto industry has switched from 12.9 to 10.9
                            Now that was fine when you had a Hexhead bolt with the marks,
                            but if it is a socket head capscrew, you may not know what the screw is.
                            Only the box knows!

                            Next item
                            hydrogen enbrittlement(H-E)..lots of comments thrown out, but the facts are not discussed.
                            Plating a fastener does not make it bad !
                            Look at NASA and the space program ...
                            POOR manufacturing practices, make plated fasteners a real problem.
                            Thats why a good bolt maker is needed for complete safety.
                            I laughed at the acid dip coment in one of the paragraphs.
                            A reall no-no if it is the wrong acid.
                            To reduce H-E, the following must be adhered to.
                            No Clorinated hydrocabons are allowed when machining (certain cutting fluids !)
                            Pre heat parts
                            Alky cleaning.
                            Post heat treatment !
                            Anything less than the above can and will give H-E

                            As you can see, someguys will cut corners and thats why they have the H-E failures. The easy way out, is to go for lessor grade bolts, larger in size.

                            thanks for listening


                            • #15
                              That pic of the bottom bolt I posted isn't just a surface finish problem. It's hard to tell in the pic but it isn't even round and the surface is all hills and valleys at least 20 thou deep plus the points on the head are partly rounded off.
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