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Thread: Bolts

  1. #1
    Join Date
    May 2003
    Vancouver's Island

    Default 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.

    Free software for calculating bolt circles and similar: Click Here

  2. #2
    Millman Guest


    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. #3
    Join Date
    Oct 2002
    Pass Christian, MS


    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. #4
    Join Date
    Jan 2003
    On the Oil Coast,USA


    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. #5
    tattoomike68 Guest


    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. #6
    Join Date
    Nov 2005
    Mount Clemens, Mi


    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. #7
    IOWOLF Guest


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

  8. #8
    Join Date
    Jan 2003
    Deep in the Heart of Texas!


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

  9. #9
    Join Date
    Jan 2006
    Keystone State

    Post 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. #10
    Join Date
    Dec 2005
    Sequim, Wa.


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

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