Countersink hole definition

[Masibanda-CE]

What is the purpose of the "Countersink" hole definition?

At first, I thought it was for Counterboring however it doesn't create a hole all the way through the part. Also, it doesn't drop the head into the counterbored material. What's the intention here ... does anyone use it?

[acbsdesign]

@Masibanda-CE 

Sometimes I use them and give fabricators the nc files, usually trying to keep theoretically the head of the countersunk bolt 1/16" below the top surface,  angle of the head is usually 82 degrees. If the material is galv, the head will be flush with the top surface, so 1/16" is a common default for head to top surface distance.

It is used in plates supporting bridge stringers, in barges, walk pates (diamond plates) as well.

[Masibanda-CE]

@acbsdesign Ilko, I think you're referring to the "Countersunk" hole definition. Those do make sense and work as I would expect. It's the definition called "Countersink" that makes no sense to me.

Cheers,

Gary

[acbsdesign]

Ok, ok, I see what you are saying, I have no idea what is this for.

[Julio_Soto]

I'm glad I'm not alone on this.

[acbsdesign]

There are countersink drills on the market, but I have never seen countersink holes in a project. It may be some mechanical shops thing.