On Apr 3, 10:46 am, "Lawrence" wrote:
On Apr 3, 10:27 am, "AlanC37" wrote:

I need to make a 3.5 inch diameter hole through a log wall for cables and
pipes for a big split type of heat pump. The total length, including
plaster and siding, will be about 15 inches and the logs are about 12 inches
thick. I have, so far, been unable to find a long enough drill at 3.5 inch
diameter so am considering drilling a number of small holes (3/8 inch) and
chiselling out the remains of the log. Might be a bit tough for an old guy
so I am hoping someone could advise me of a better way. I'm sure big holes
in logs often need to be drilled but don't know how. Any advice will be
gratefully received. Thanks, Alan C37

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Have you considered drilling from each side toward the center? It is
better to drill a through hole, no doubt but I'm sure you can also
measure as accurately as you can from each side and use a square
against the building to guide your bit. After you put the pipe
through you will probably use some type of caulk or foam anyway.

Good idea Lawrence,,I would use one of the smaller bits and drill
through dead center then just follow that from both sides to meet in
the middle..Drilling at a slight angle down from inside to out will
prevent water from running in if the outside seal ever leaks.