If you're going to drill them, start with something smaller. Go in there
with an 1/8" at fairly high RPM and use some pressure on it. Then open
it up with the 1/4" at a slower RPM. If you can hold it steady, even
start with a 1/16.

You have the right idea but if you are going to remove something as
small as 1/4 inch then you need more accuracy especially if you have
multiple bolts.

You need a magnifying glass and pin punch.

You need a drill as small as 1/32 inch

You need a very high speed stationary drill.


You use the small drill for a perfectly centered pilot.
Drill 1/8 inch deep. Then step up to the largest easy out
size for a 1/4 inch bolt. Drill all the way through if possible.
If the easy out doesn't work then keep drilling larger until
one of two things happen.

1. The hole becomes clean enough that you can chase it with a tap.
2. The hole has to become oversize so that you can install the
appropriate insert to accept a 1/4 inch bolt