Drilling tough concrete

alistairedw

alistairedw

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I spent this morning installing panels of anti slip onto our dinghy park slipway. Drilling the holes for the anchor bolts wasn't too tough until I got to the top section where there is a high % of flint in the concrete.

My hammer drill is fairly powerful, but I just couldn't get the holes deep enough. If I invest in a super hard tipped drill will I be able to drill through the flints? What is the best type of drill bit for this kind of job?
 
Go to your local hire shop and rent a Hilti Drill. Available in various sizes the TE5 or TE6 will be adequate up to 16 mm holes or will work happily on 6 mm drilling. The SDS bits are not cheap but one will do many holes. For professional construction use nothing drills like them. Believe me the difference from a high revving B&D type drill is remarkable.
 
There is a cheap tool that would do the job, I have one but cannot remember what they are called, Hand held with hardened point, 4 inches long, and you hit it with a lump hammer, will break the stones and then you can use drill again.
Sure any hard ware store will have them.
 
Another vote for Hilti. The average DIY "hammer" drill wouldn't scare a sandpit.

Get'em at any decent hire shop.
 
I have a bosch SDS drill (build your own house and you can buy lots of tools !!) and they are so much better than the normal type. I know that Screwfix do an SDS one for about £30-£40, not sure if it is any good but it may be almost as cheap as hiring one. Remember that SDS drills take SDS drill bits not normal ones and they are anything but cheap
 
The Screwfix SDS drill works very well. They were about 20 quid when I last looked, and are easily worth it. They also do a cheap set of SDS drill bits and chisels which is worth getting, too. (Not the highest quality, but quite reasonable).

It was the only thing I could get to drill into REALLY hard engineering bricks. (I tried to use it on modern engineering bricks, though and it just shattered them).

If you hire, it sometimes helps to go to a local independent (not HSS) and do a deal on a same day return (assuming you only want it for a few hours) - If it's still in the shop at lunchtime, chances are that they won't get a trade hirer for it that day, so as long as it's back before closing time, anything they get is a bonus.

Andy

Edit: If you want to stick with your own drill, try to get hold of a "Mason Master" (or something similar) brand drill bit - you'll probably need to go to a builder's merchant, or decent tool shop to get one. They're only tungsten carbide tipped masonry drills, but they're a class above anything you'll find in "Bodge-it & Quit".
 
You could do with a diamond core drill. There are some you can use on a custom drilling rig water cooled etc but there are some cheaper things you can use on normal drills wet or dry.
Have a look on ebay.
 
Go to B&Q they do one of their own brand ( pro ) SDS Hammer for about £20-30 I bought one of them about three yeard ago, and I am a plumber/tiler and use it very often for drilling through walls floors, and then with a paddle in it (off hammer) for mixing buckets of floor tile adhesive, never had a bother with it, "Great tool" If you keep it clean you can take it back when job is done and get your dosh back, cheaper than hiring /forums/images/graemlins/blush.gif
 
Don't know what I'd do without one, these days. I never use the hammer action on my ordinary drill anymore, just the SDS for brick, masonry and concrete. With the rotary action switched off they are brilliant for demolition and breaking up slabs etc, at least the limited amount I ever need to do. Just keep the chuck clear of the horrendous amount of dust that tries to settle there.

Got to be a 'Best Buy' item for your toolbox.
 
Yep, I hired a Hilti to drill some holes in rock to anchor a jetty. Cost 30€ for the day.
Then I bought a cheap local "own-brand" (but made in China) SDS drill for the same price and drilled the same kind of holes just as fast. Keeping water flowing down the hole keeps the bit cool and washes away the dust/debris. Also the dust doesn't fly to far 'cos its wet!
Bought it 3 yrs ago and still going strong...

-steve-
 
Thanks everyone for all the excellent advice.

A kind forumite is lending me a big Hilti drill/breaker, so I don't think the concrete is going to frustrate me for too much longer!
 
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