Large Forstner or multispur bits will drill flat-bottomed holes that don't go. When boring deep with a Forstner bit or multispur bit or holesaw, clear the chips .
Forstner bits are guided by the wide outside rim of the bit, unlike most drill bits, which are guided by the tip. Because of that, they can be used along with a drill press to drill angled holes, holes that partially overlap, and holes on the edge of the material.
The bits are Wood River brand and the low price should have scared me off, ($ 31.00-$33.00). I chucked up the larger and using the slowest .