Lee Valley counterbore countersink set

[Bill Dufour]

Looked at the design. What is the point of having two collars? seems like a needless complication over a longer cutting bit with two screws in that one piece. The one piece design doubles the torque required to spin the cutter on the drill shank.
I have had that stepped flat drill for decades always wondered why not just a continuous flat. I think I figure it out today, I think. It is for a hole saw and it prevents the drill from pulling out and staying behind in the waste.
Bill D

[Edwin Santos]

Looked at the design. What is the point of having two collars? seems like a needless complication over a longer cutting bit with two screws in that one piece. The one piece design doubles the torque required to spin the cutter on the drill shank.
I have had that stepped flat drill for decades always wondered why not just a continuous flat. I think I figure it out today, I think. It is for a hole saw and it prevents the drill from pulling out and staying behind in the waste.
Bill D

The second collar in the LV set is a depth stop. So you can vary the size and depth of your counterbore. Or if you simply want your counterbores consistent.

[johnny means]

[QUOTE=Mark Rainey;3122649]

It's an inherently flawed design. I switched to these years ago have never had any problems.[/QUOTE

Johnny, who makes these?

I buy the Amana versions. They're not cheap, but the carbide is long lasting and can be resharpened many times. They fit any old cheap drill bit.

[Mark Rainey]

I heard back from Lee Valley. They recommend grinding a flat in the drill bit, as Doug & Bill recommend. They said some drill bits have a flat already ground. I will try this approach. The Amana counterbore looks impressive - and the spinning stop collar looks interesting - of course it is expensive.