Ball end cutters

[Speedy Builder5Participant @speedybuilder5]

I need a 5/16″ or 8mm diameter ball end mill just to make a round recess at the bottom of a 5/16″ dia hole.  Would a sort of “D” drill do this. I only have two components to make in brass or Al-bronze.

Ps:-  These are the for the cavities behind the valve heads on Farm Boy hit and miss engine and the bottom of the recess has a 1/8″ hole for the valve stem.

Bob

[JasonBModerator @jasonb]

Yes a D bit will do and should cut fairly easily if you drill and ream the valve stem hole first

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