D bits.. which part to angle?

[Tel]

For cutting ball seats your D-bits need to be shaped thusly - this leaves the ball sittin' on a little raised 'crater' & it will seat much better when you give it a bash - angles are exagerated

[Tel]

Wa'al this where you & I differ Madman - I alluz use 'em 'flat' up - frequent withdrawal & brush away the chips - works for me

steammadman said:

Don't forget to feed the "D" bit into a pre-drilled hole up-side down,or
with the flat to the bottom

[paul]

Thanks Tel, I understand... this'll make a little 'volcano' shape for the ball to sit on.

[Tel]

Yup, that's the idea, doesn't need to be much, but it needs to be there

[chameleonrob]

"this'll make a little 'volcano' shape for the ball to sit on"
that's what I was failing to describe in my post with a reverse chamfer, lets just hope that my engineering skills are better than my dicriptive ones...