A reamer makes a smooth, round hole, where a twist drill used with a hand drill cannot make a hole of the same quality. You might consider using left-hand fluted, straight reamers. The flutes have a left hand spiral which pushes the chips ahead (in this case, down) instead of drawing the chips out - and without unnecessary heat build up of the single flute or straight flute reamers. They are available in letter sizes and decimal sizes. They typically have square ends that can be chucked into a tap handle, but can also be chucked in a drill. As a source, I would suggest machine supply companies but I often find this kind of stuff on Amazon Prime.
Reamers generally should be removing no more than 0.010" material from a hole. If the hole is smaller, drill an undersize hole first. You should carefully measure the holes and the tuning pins, calculate your finish hole size, and then select a reamer to give you the finish hole dimension.
Thanks,
Keith Bowman
------------------------------
Keith Bowman
Harrisburg PA
717-599-7782
------------------------------