All Replies on What is this feature called?

Keyhole router bit:

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

Perfect, thanks!

Hint, use small diameter straight router bit (same diameter as smaller diameter on keyhole bit) to remove as much as possible first, then use keyhole bit to clean up and provide final shape.

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

cut the slot with a straight line bit first, then the key way bit, they dont take a lot of strain on them.