My dremel has a motor
unit from which a flexible drive extends to the bit. The diameter of the bit is about 1.2cm. I cut a 1.8cm hole just above the existing cable exit hole on the leading edge of the mast
. By taping the end section of the flexible drive unit to the long sturdy metal rod, I could control the dremel when it was deep inside the mast
, cutting the access hole in the conduit which lay directly on the opposite side of the mast. The only vision was via the camera
, which was able to be passed through the existing hole just below the dremel port. I will have to bung or cover the new access hole as it is now no longer required.
No picture, but should have in retrospect.