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  • Bolt Grades...for sure?

    Touched on it a bit in the HF engine hoist thread. Regardless of the merits of Grade 5 vs 8 bolts - and the identifying marks on the cap head - are all "grade 8 bolts grade 8 bolts?" Given the worldwide sourcing of so much stuff these days does the bolt head wear the grade symbol because it is held to a North American standard or it wears it because it meets the standard of the manufacturing country?

  • #2
    Originally posted by Dunc View Post
    Touched on it a bit in the HF engine hoist thread. Regardless of the merits of Grade 5 vs 8 bolts - and the identifying marks on the cap head - are all "grade 8 bolts grade 8 bolts?" Given the worldwide sourcing of so much stuff these days does the bolt head wear the grade symbol because it is held to a North American standard or it wears it because it meets the standard of the manufacturing country?
    You are the only ones* using North American standards so thats what they at least pretend to fullfill.

    *) maybe also Burma.
    Location: Helsinki, Finland, Europe

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    • #3
      Bolt Grades are set up by ANSI , an American Standard set up for bolts made in America.
      Foreign makers of bolts should honor those standards when they sell bolts in the USA
      The head markings are supposed (!) to reflect the meeting of those standards.

      The rest of the world uses a Metric Standard ( DIN ie) that has similarities------ except for Allen Head Screws ( SHCS, or SHSS)
      The USA has only one standard , which is stronger than a grade 8 bolt strengths.
      A grade 8 is 140,000 ~ pound Tensile Strength and a SCHS screw MUST be 176,000 (!) or better.
      The comparable rating for a Metric screw is 12.9 DIN and the screw heads are marked as such , while American SHCS 's must have specific head markings that only the manufacturer uses.. ( So Allen, Cam Carr, HoloKrome, and Unbreako have unique designed markings)
      Unfortunately Metric SHCS makers can make 10.9 or even lesser quality screws down to mild steel.
      That's why when you buy some Chinese tools, the screw sockets round out ...total crap

      Rich
      Last edited by Rich Carlstedt; 10-19-2017, 11:10 AM.
      Green Bay, WI

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      • #4
        And I thought grade 5 bolts were manufactured by 5th graders and grade 8 bolts were made by 8th graders.

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        • #5
          Originally posted by Rich Carlstedt View Post
          A grade 8 is 140,000 ~ pound Tensile Strength and a SCHS screw MUST be 176,000 (!) or better.


          Rich

          That's just a tad bit misleading. You can buy stainless (or nylon - hah!) socket head cap screws that don't meet that. Usually it's immediately obvious what material the fastener is made of (i.e. alloy steel vs. stainless vs. plastic) but you can also buy black oxide 18-8 stainless SHCS. They look like "normal" SHCS but are much weaker.

          Example here:
          https://www.mcmaster.com/#socket-hea...crews/=19vqocj

          Black oxide 18-8 SHCS w/ 70000 psi tensile strength

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          • #6
            Originally posted by Rich Carlstedt View Post
            Bolt Grades are set up by ANSI , an American Standard set up for bolts made in America.

            The comparable rating for a Metric screw is 12.9 DIN and the screw heads are marked as such , while American SHCS 's must have specific head markings that only the manufacturer uses.. ( So Allen, Cam Carr, HoloKrome, and Unbreako have unique designed markings)
            Unfortunately Metric SHCS makers can make 10.9 or even lesser quality screws down to mild steel.
            That's why when you buy some Chinese tools, the screw sockets round out ...total crap

            Rich
            Metric bolts are required to have manufacturer identification also. Maybe the Chinese make fake extra-special crappy metric products for american products and extra crappy imperial bolts for european market
            Metric hex heads are often 4.6 class in chinese products imported to here, no lying there as that is crappiest and softest bolt ever.

            Somewhere out there is a database for manufacturer head stampings registered to European use.
            For example local cheapo auto store 12.9 allen heads are stamped "TUZ" that points to here http://www.tuz.com.tw/eng_product.html
            Location: Helsinki, Finland, Europe

            Comment


            • #7
              Originally posted by Fasttrack View Post
              That's just a tad bit misleading. You can buy stainless (or nylon - hah!) socket head cap screws that don't meet that. Usually it's immediately obvious what material the fastener is made of (i.e. alloy steel vs. stainless vs. plastic) but you can also buy black oxide 18-8 stainless SHCS. They look like "normal" SHCS but are much weaker.......
              Sorry , but in my 50 years of manufacturing experience, I have never seen a black coated stainless steel fastener.
              And yes, they are quite a bit weaker ( by 2/3 x) and ANSI standards apply, but for that material. ( SS SHCS)
              I think the poster was referring to steel , as stainless is not available in grade 8 or even grade 5 .
              There are some special hex head bolts, like Supertanium that exceed the ANSI Standards
              http://gwinnupcommunications.com/PF_...174AwHex1.html
              Price is a big factor.

              Rich

              edit
              There is some good info here for those interested in some fastener specs
              http://practicalmaintenance.net/?p=386
              Go down until just short of the bottom where a Cap Screw is shown with the word "length" under the threads.
              Please note the cross hatching on the head ..This happens to be a UNBRAKO brand screw.
              It has 2 small cross hatches at the top with an embossed straight hatch on the body of the head itself. This is their mark.
              Allen and Cam Carr and HoloKrome have their specific markings, and so do the foreign makers.
              All this is for trace-ability
              Last edited by Rich Carlstedt; 10-19-2017, 08:22 PM.
              Green Bay, WI

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              • #8
                Originally posted by Rich Carlstedt View Post
                Sorry , but in my 50 years of manufacturing experience, I have never seen a black coated stainless steel fastener.
                ......
                You need to get out more:

                https://www.albanycountyfasteners.co...ners-s/860.htm
                CNC machines only go through the motions

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                • #9
                  Originally posted by J Tiers View Post
                  Yep, we get them from Mcmaster Carr too. The coating is to prevent siezing between two stainless parts.

                  Comment


                  • #10
                    Grade 5 max is 120,000
                    Grade 8 max is 150,000
                    AHCS max is 170,000
                    Grade 9 max is 180,000

                    Is a low price to pay for 9 grade over a failed bolt and machine tool in pieces
                    I would also add a plate on both side of the ram to close up the gap too making the engine hoist safer
                    There is only one tool I did have fix after getting from HF that a 4x6 band saw ever thing else had to work on


                    Dave


                    Originally posted by Dunc View Post
                    Touched on it a bit in the HF engine hoist thread. Regardless of the merits of Grade 5 vs 8 bolts - and the identifying marks on the cap head - are all "grade 8 bolts grade 8 bolts?" Given the worldwide sourcing of so much stuff these days does the bolt head wear the grade symbol because it is held to a North American standard or it wears it because it meets the standard of the manufacturing country?

                    Comment


                    • #11
                      When you get into "what are you willing to pay for being safe", there is no real answer short of "it's open-ended, no amount is too much". In that sort of debate, the person arguing for safety has an advantage, and can ALWAYS make the person who argues for a "good enough" solution look like a greedy fool who cares about money more than safety. It's an unwinnable argument, I have been in that sort of thing on standards committees.

                      Getting back to reality, if a bolt of grade 5 that fits in the position is strong enough by a good factor of safety (margin), then there is no need to get into the "stronger is always better" debate at all. The thing is rated at 2 tons, and a grade 5 of 5/8" will take several times the force put on it by 2 tons..... argument is over.
                      CNC machines only go through the motions

                      Comment


                      • #12
                        Originally posted by Rich Carlstedt View Post
                        Sorry , but in my 50 years of manufacturing experience, I have never seen a black coated stainless steel fastener.
                        And yes, they are quite a bit weaker ( by 2/3 x) and ANSI standards apply, but for that material. ( SS SHCS)
                        I think the poster was referring to steel , as stainless is not available in grade 8 or even grade 5 .
                        There is stainless bolts up to metric 12.9 so equivalent to grade 8. And if you go to custom order grades you can get Bumax Ultra stainless bolts up to twice the grade 8 strenght. NOT cheap.
                        Location: Helsinki, Finland, Europe

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                        • #13
                          I've seen 1" grade 8 bolts break at the thread transition to the bolt body - these were used on the front suspension of a JD tractor with loader. Grade 5 bolts from the same supplier have continued to hold up over time (several years). I don't know what JD originally specified - probably an OEM fastener with no commercial cross - but as J Tiers said, stronger is not always better. I believe the grade 5 bolts may flex a bit more than the 8's under load so they last longer in this particular application.

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                          • #14
                            IMO, Stronger is always better if you have the choice of grade 5 or 8 at the same cost/price/availability... Especially for us home shop guys that may decide to reuse bolts from previous projects for new projects... Case in point, you can take those grade 8 bolts out of your old project that only needed grade 5 and use them in your new project that does indeed need grade 8...

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                            • #15
                              Originally posted by HWooldridge View Post
                              I've seen 1" grade 8 bolts break at the thread transition to the bolt body - these were used on the front suspension of a JD tractor with loader. Grade 5 bolts from the same supplier have continued to hold up over time (several years). I don't know what JD originally specified - probably an OEM fastener with no commercial cross - but as J Tiers said, stronger is not always better. I believe the grade 5 bolts may flex a bit more than the 8's under load so they last longer in this particular application.
                              I'm sure there is something more to the story... Either the original grade 8 bolts were subjected to significantly more stress than the current grade 5 bolts, or they simply were not true grade 8 to begin with..

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