I made a long boring kit by taking a block of timber about 8" long and 1½" square, drilled an 8mm hole through it length ways, marked the TOP (any face would do) and cut it in half, then I enlarged the 8mm to a 10mm hole on one block.
Put a 10mm drill bit through one hole, and an 8mm (actually used threaded bar as that is what I had but anything will do so long as it is smaller than the drill bit) position it carefully weld it up grind off the splatter (I am not great at welding) then I welded some more as a T handle on the end and I have a drill bit that will go all the way through a lamp.