127mm core drilling error, help please

[Ed Sirett]

Instead of using the a guide drill it would have been better to use the blunt guide rod. The surface you wanted to start in must surely be quite weak (not brick like) to have opened out so much. I don't think the guide rod protrudes much more than 20-25mm from my core drills. Most of the kit was obtained from Screwfix although I've added some stuff to it later.

I suppose you may have been trying to drill from inside. I don't suppose you can get access to it from the other side? Perhaps that was why you were drilling 127mm?

If all else fails and you are really shafted then I guess you can fix a couple of battens on the wall in a V so as to support the drill until it starts.

[marvelus]

Thats where the arbor goes.

[Brian Sharrock]

Genuine question; when 'producing' a wide hole through a cavity wall ( plaster, brick, cavity, brick, rendering) should one drill a (narrow) pilot hole all the way through -then, and only then, widen the hole using the 'big' bit with its 'guide bit' fitted centrally.?

[John Rumm]

If you want to be able to drill from both sides then that is the way to go. Alternatively you can just drill from one side, either using the pilot bit all the way through, or just to get you started after which you remove the pilot altogether and rely on the already cut section to guide you. (the inner leaf acting as a guide for the outer leaf etc)