How to use hole countersink drill bit

[Alberto-sp]

Hello. I don´t know if that is the correct name for this tool in english



I drill a hole and then I use it and sometime "bite" and make a nice countersink, but sometimes don´t "bite" and only turn. I remove and apply 1, 2, 3 times and sometimes star biting and make the countersink. So, once it start, works nice, but sometimes it is hard to start it.

What am I doing bad?

Thank you

 

[benmychree]

It may be just dull; a single flute countersink would be a better tool for countersinking, the one you pictured is best for deburring.

 

[Aukai]

It is a zero flute counter sink/deburring bit.

 

[Alberto-sp]

Thanks for yor answers.

Like this one?

 

[projectnut]

Thanks for yor answers.

Like this one?

Yes those are single flute countersinks.. If you're just using them for deburring any angle will do. If you're using them as countersinks for flat head bolts the most common for imperial fasteners is 82*. The most common for metric fasteners is 90*, and the most common for aircraft fasteners is 100*.
In my opinion the best brands are KEO and MA Ford. I have both brands in several different sizes and angles. The MA Fords are nearly 40 years old and have only been resharpened twice. The KEO's are about 15 years old and have never been resharpened.

 

[Alberto-sp]

Thanks for your answer