Simple but recommendation?

[ClayM325]

I am working on a project where I have to cut 100's of slightly over .5" holes .6" deep, then cut a .25 hole an additional .030 into the bottom of it. Is there a 1/4" bit I can use that will drill both cut the bigger hole, and the smaller hole inside of it but won't leave the rounded over hump in the middle since it's not traveling? This is hardwood by the way (white oak).
Thanks!

[JimDav]

Years ago I had a drill bit specially made to do that on a drill press. Have no idea where. Now, with the Bot I just set up a tool path to do it. Be careful when drilling a .25 hole with a .25 bit though going only .03 you should be ok. After starting 2 fires, I now use a 5 mm bit to make .25 holes.

[bleeth]

You just need a 1/4" mortise bit.
I believe Centurian has them.

[ClayM325]

You just need a 1/4" mortise bit.
I believe Centurian has them.

I’m having trouble finding one. Seems like I would need a down cut correct? Only thing I’ve seen is compression. Also, looking at the profile it looks like it would still leave the bubble in the middle?

[bleeth]

A compression mortise should work fine. Putting a hole, or pit, in the middle of another pit is a pretty standard operation.
Another option is to use a 3/16" bit using area clear for all.

[dlcw]

I only use boring bits for all my hole drilling operations. I run the spindle at 6400RPM. Nothing gets hot at these speeds and the holes are PERFECT, top and bottom. I stopped using cutting bits to drill holes years ago and am very glad I did. toolstoday.com has boring bits in all shapes and sizes.