On Jun 4, 6:21*am, "EXT" wrote:
I have used them all. FIrst of all, I am sure you don't really have a cinder
block wall. Many people wrongly call concrete blocks, cinder blocks which
were made from coal cinders. Making a hole in real cinder blocks is easy,
they are soft and can be punctured without much effort. Now concrete blocks
are different, they are hard and brittle.

You can use any method and it will not crack the block unless you use
extreme force to do the job. The easiest is to rent a large drill and bit
from your local big box store. The hardest part is to find out if you have
two core or three core blocks. New walls will be 2 core. Whatever method you
use will work best if you miss the web in the block. You may have to do some
small hole drilling to find the core and web. Old blocks with 3 cores are
easy to work if you drill through the center and hit the center core. Newer
blocks will only have two cores and you will hit the web if you drill in the
middle, so you need to drill 1/3 of the way from the end. The year that
manufacturers changed to two core blocks will vary according to when they
changed machines and moulds.

"Robert Green" wrote in message

...



What's the best way to punch a 2" hole for a drain pipe through a cinder
block wall?

I've researched a variety of suggestions from a hammer and a star drill,
to
drilling a ring of small *holes in a circle with a carbide bit to renting
or
buying a diamond tipped core bit. * What's the best way of doing it so as
NOT to crack the block?

--
Bobby G.- Hide quoted text -

- Show quoted text -

Excellent points. The worry about 'crackign the block' is no biggee.
The likely hood of making a tight fitting 2" hole without using a core
drill is zero so it will have to be patched in any case. I have done
the BFH route and patched the remains later, used a 3/8" hammer drill
and small concrete bit and probably a few other methods. If I ever
have to do it again it will be 'rent a real electric hammer and decent
bit, drill a ring of holes and knock out with hammer' Of course being
careful to miss the web.

Harry K