The lines on the head of a bolt indicate its grade. SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will indicate an SAE grade 8 fastener. These are the most common grades, but there are others. Our Fastener Identification Markings Chart has a complete list of bolt grades with accompanying head markings.
MNP is Michigan Nut Products Corp of Utica, MI
CP is Chandler Products of USA
I have a question, who uses the atomic head stamp of three oval circles on top of each other 120 degrees apart?
@Herb- Sorry, but we looked through our head marking information and did not immediately find the head mark you describe.
Screw with mark F.P
@Emil- That head mark is not one we are familiar with.
Can you tell me who manufactures Hex Bolts with Makers Mark “BY”?
@Howard- Apologies, but we are not familiar with that marking.
Don’t know if you got an answer for the “BY” head mark but that is for Ben Yuan from Taiwan.
Hi,
I’ve looked through the patent office registered manufacture head insignia however I cannot locate E
I’m restoring an antique oak dining table and there are 4 bolts with the letter E
Any idea or point in the right direction would be appreciated!
Thanks!
@Karen- I looked through an old head marking catalog and found several manufacturers who all use ‘E’. I am not terribly familiar with any of these companies and so do not know if any are still in business. E&E Fastener in Michigan. Eagan Machine in Connecticut. Ellis Precision in Texas. Engineering Materials Co in California. Erico Fastening in New Jersey. Erie Bolt in Pennsylvania. Erie Manufacturing in Texas. ESMET in Ohio. Euclid Industries in Ohio. Good luck.
Do you know the mfg of an B8M Stud that has the marking TNE ?
Thanks
@Leon- Apologies, I looked through all my information as was not able to find a registered marking of TNE.