Need Help ID this Nut & Bolt

[W8BYA]

Howdy group. I came across a very large number of these new nuts & bolts but am not familiar with the stamping on the head. I suspect they are metric as the bolt measures exactly 3 cm in length and a standard 5/16-18 coarse will almost thread on but does not. I read it as 3F on one side then 8.8 across from that. Looks like a heavy Chromate coating for corrosion resistance.

 

[ptsg]

It's an M8x1.25 30 mm long bolt. The 8.8 is the grade for metric bolts.

In the land of metric, we don't even bother to mention the pitch (1.25 in this case), only if we actually want a fine thread or something. So we would just call it M8x30 mm bolt.

 

[JethroB]

It's an M8x1.25 30 mm long bolt. The 8.8 is the grade for metric bolts.

In the land of metric, we don't even bother to mention the pitch (1.25 in this case), only if we actually want a fine thread or something. So we would just call it M8x30 mm bolt.

View attachment 745222

Ok, I understand the 8.8 grade part, but how did you know M8x30mm? From the markings?

 

[ptsg]

Ok, I understand the 8.8 grade part, but how did you know M8x30mm? From the markings?

The thread diameter and pitch of the M8 and the 5/16 bolts or nuts are very close to each other. It will actually work if you force it there, but you may end up with a slight mix between a 5/16 and a M8 thread.

As far as the length, the provided metioned in the first post.

 

[W8BYA]

It's an M8x1.25 30 mm long bolt. The 8.8 is the grade for metric bolts.

In the land of metric, we don't even bother to mention the pitch (1.25 in this case), only if we actually want a fine thread or something. So we would just call it M8x30 mm bolt.

View attachment 745222

Hey that's great, thank you. A boat load of grade-5 bolts I can live with. Am I close in assuming the 3F marking is for 3 cm? But what about the F marking?

 

[ptsg]

Hey that's great, thank you. A boat load of grade-5 bolts I can live with. Am I close in assuming the 3F marking is for 3 cm? But what about the F marking?

That would be a manufacturers marking/ID, so not really important.

 

[AWSubie]

3F is Fontana Luigi

 

[W8BYA]

3F is Fontana Luigi

Darn it ! I was hoping these bolts were Ferrari or maybe Lamborghini

Thank you for letting me know. Fascinating all that information can be easily put on the head of a bolt.

 

[Root Cause]

There are times when English and metric overlap. It can be dangerous.
There are lots of ways to size a bolt. At my Lowes or ACE hardware stores have these and you can buy them as well.

Keep something close by. It will save you time and money the first time you force a bolt only to find out it won't hold and the threads are stripped.

I have a set of these in my tool bag.

 

[W8BYA]

There are times when English and metric overlap. It can be dangerous.
There are lots of ways to size a bolt. At my Lowes or ACE hardware stores have these and you can buy them as well.

Keep something close by. It will save you time and money the first time you force a bolt only to find out it won't hold and the threads are stripped.

View attachment 745226​

I have a set of these in my tool bag.
View attachment 745227

Both of these are great ideas. Normally I would go to my local fastenal (which is just 5 min away) but they have closed there main door, open only for P/U's etc. What a shame as they are a wonderful source.