Bolts

[Evan]

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.

[Millman]

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.

[WJHartson]

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.

Joe

[wierdscience]

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.

[tattoomike68]

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

[PTSideshow]

[IOWOLF]

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

[CCWKen]

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

[TECHSHOP]

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.

[Scottike]

Looks like a clockmakers bolt to me.
make a clock out of it.