Drilling old concrete fence posts?

[A.Lee]

I've got a line of old concrete posts bordering my house, I'd like to put up a wooden fence, but unfortunately they are spaced wrongly and intermittently for panels, so the best thing would be a featheredge lapped fence. Trouble is, I cannot drill into these posts to screw in the cross battens. Invariably I get in half inch or so, hit a stone, then the drill rapdily goes blunt, and goes no further. I havent tried a diamond drill bit yet, but am not too keen to splash out on one if that is going to wear out after 2 or 3 holes. Any thoughts on what I need? SDS drill with diamond bit? Give up and dig out all the old posts? Thanks for any pointers. Alan.

[John Rumm]

It may be that you are hitting steel reinforcing bar in the post rather than a stone.

It it were a stone, a SDS drill and bit would romp through it easily.

If it is rebar, then you can get rebar cutting masonry bits that ought to do the job. (Just positioning the hole in a different location will probably help you miss the rebar).

[ARWadsworth]

Make panels to fit. It is probably cheaper.

Adam

[The Medway Handyman]

SDS with a normal masonry bit. Done it loads of times.

[dennis]

Get some galvanised steel strapping from a builders merchant and wrap it around the post and screw it to the arris rail.

[Roger]

The message from John Rumm contains these words:

Yes, but the holes already drilled will let in water, the rebar will rust and the concrete post will start to disintegrate. Any holes drilled need filling pdq. Any others drilled in the post might cause a long term problem even if they don't hit the rebar.

[Malcolm Race]

If the posts are morticed for arris rails, there are arris rail bracket which will fit into the morticee so that you can screw them to the new arris rails

Malcolm

[A.Lee]

No being picky, but why is a SDS drill with a normal masonry bit, better than a normal hammer drill with the same bit? Vibrates/hammers more, or something else? Thanks Alan.

[Lurch]

On Fri, 18 May 2007 19:01:26 +0100, alan@darkroom.+.com (A.Lee) mused:

Basically SDS drills use a more efficient hammering mechanism. The end of the bit is directly struck whereas a normal percussion drill just sort of rattles the chuck around a bit, really reall lossy way of transferring energy.

[Andrew Mawson]

cross

It's all a matter of 'oomph' - much more 'oomph' in the hammer action of an sds drill than the cam operated ones on 'hammer drills'. Most SDS drills use a pneumatic coupling arrangement giving greater travel.

AWEM

[Chris]

"Andrew Mawson" wrote in news: [e-mail]:

These posts normally have reinforcing bars in them just to make life more difficult Chris

[John Rumm]

[The Medway Handyman]

True, but drilling a 30mm deep hole for a plastic plug shouldn't reach the rebar.