# What's the proper name for these bits!



## lpeedin (May 22, 2014)

I bought several of these along with a handful of square end bits for $1.00 each at a flea market. 

This one is 5/16” on the small end and exactly what I needed to countersink 5/16" cap screws. I'd love to have several more sizes but can't seem to find them. I tried searching for step bits but the only results were the cone shaped bits for step drilling holes in sheet metal. 

Thanks for any feedback. 





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## JimDawson (May 22, 2014)

That looks like a drill / counterbore combo bit, I wasn't able to locate that exact bit in a very quick search.

You can buy counterbores from all of the tooling suppliers.  Some have a fixed pilot, some have an interchangeable pilot.  If I were going to buy another set, I would get interchangeable pilots.


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## lpeedin (May 22, 2014)

Thanks Jim, I just found them on McMaster Carr as counterbore bits. According to their prices, I think I found a deal. .


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## JimDawson (May 22, 2014)

lpeedin said:


> Thanks Jim, I just found them on McMaster Carr as counterbore bits. According to their prices, I think I found a deal. .



My pleasure.  A deal from Mcmaster?  I would go buy a lottery ticket)


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## lpeedin (May 22, 2014)

JimDawson said:


> My pleasure.  A deal from Mcmaster?  I would go buy a lottery ticket)


What I meant was, based on MC's price, I got a deal at the flea market.


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## Marco Bernardini (May 23, 2014)

You are really lucky!
Here the flea markets offer mainly things like this one:




These counterbore bits, sometimes called "stepdrill", allow you to correctly place a cap screw, with a flat bottom under the head.
Generally, without these bits (and without an end mill) the hole for the head is done with just a larger bit, and this has two drawbacks: first, to center exactly the head and the screw could be difficult (while with such a bit you can even make it with a hand held drill), and second the head gets an uneven support, limited to the circumference edge.
 :nono:

On eBay even Chinese counterbore bits are over $15 each, at least the metric ones I need, so you really made a good deal.


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## genec (May 23, 2014)

I have always called them step bits, I came across a box of assorted for $1.50 a pound, so far haven't found a use for them.


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## Marco Bernardini (May 23, 2014)

genec said:


> I have always called them step bits, I came across a box of assorted for $1.50 a pound, so far haven't found a use for them.



If they are metric and you find a way to ship them to Italy for a very reasonable price, I offer you $3/lb… a deal


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## kwoodhands (Jan 27, 2016)

lpeedin said:


> I bought several of these along with a handful of square end bits for $1.00 each at a flea market.
> 
> This one is 5/16” on the small end and exactly what I needed to countersink 5/16" cap screws. I'd love to have several more sizes but can't seem to find them. I tried searching for step bits but the only results were the cone shaped bits for step drilling holes in sheet metal.
> 
> ...



They are called "bullet drills". The box stores and hardware stores carry them in sizes up  to 1/2".Black & Decker and maybe Vermont American both manufacture these drills. The point is good for starting the hole.
mike


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