On Wed, 09 Aug 2006 18:08:46 +0100, Mark Carver
|Andrew Mawson wrote:
|> If it is cast iron then it is likely to be VERY brittle. It is
|> possible to drill a series of small holes in the shape of the circle
|> that you need, then join then up with a file (called chain drilling)
|> but this is very tedious. Hole saws of the bimetallic 'hacksaw on
|> edge' variety are likely to be blunted very rapidly by the hard skin
|> of the cast iron, however there are now diamond encrusted hole saws
|> available that should make short work of this. When at last you have
|> your hole, you can buy a 'saddle' that clamps around the pipe
|> providing a socket for your new incomer. Of course if it is zinc, zinc
|> plated steel, or aluminium then it'll be a doddle with a normal hole
|> saw !
|Which reminds me of a related question. I've got a cast iron manhole cover
|on my patio, it's not quite level. That's not a problem, except when it
|rains a puddle forms there. I'm tempted just to drill a 4 to 6mm hole in it,
|so the water simply trickles away without producing a puddle. What drill bit
|should I use (HSS?), and what precautions etc should I take ?
Ah! but what is under the manhole cover?
Sewer and it might smell :-(
Telephone cable and it might short out the telephone.
Raise it and tell us what you can see.
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