Budgie concaves

[ashton691]

Hi all new to the site and looking to set up a new work shop but i have a quick question.

I'm looking to make my own budgie nest box concaves does anyone know what this drill press bit is called or do you know of a bit that will make a concave in a small piece of wood?

there is a video on you tube called concave1 can anyone help? sorry my account won't let me post a link

 

[sunnybob]

this guy says he's never needed a concave in 20 years of breeding
https://www.youtube.com/watch?v=INNmAYD ... 0Australia
but then goes on to tell you how to make it.