Hi, I’m trying to install a new door for our crawl space access. I need to drill some holes in our foundation. Well…many holes. I got some concrete screws and a bit for drilling in concrete, and I already have a 18v DeWalt cordless hammerdrill. I started drilling, but it is taking forever. At the rate I’m going I could get under the house for a whole weekend just drilling. Any suggestions for making this go faster? Am I using the wrong drill? The bit is carbide, I think. Is there a better bit I should be using?
Thanks. And if I don’t get a chance to reply, thanks for any answers!
Ryan
Replies
Rent a HILTI hammer drill and the HILTI or Bosch bit from Home Depot (or wherever you prefer). A cheap carbide tipped bit in a hammer drill just isn't going to do the job. The HILTI will, and it will do it RIGHT NOW!
Yeah, probably the advice to rent a heavier drill is the best advice.
You can drill concrete with a lightweight hammer drill or even a regular drill, but it goes much slower and you can be stymied by various factors. And a battery drill is a poor choice if you have more tan 1-2 holes to drill.
It's important to have a good quality bit. When drilling, don't "spin" the bit at high speed but use the most pressure you can muster and low speed, similar to when drilling steel -- spinning the bit overheats it and causes it to dull.
Often it helps to have a little water in the hole -- it seems to help give the bit some "bite". But you need to remove the bit and wipe if off often, to remove the resulting "mud".
Where you'll often run into trouble is when the bit encounters a large piece of hard aggregate that the bit simply can't bite into. This is where a sharp bit, plenty of pressure, and a little water are extra helpful. Or, if the hole's large enough and not too deep, stick a punch down it and fracture the stone with a hammer.
Sometimes you're better off with your grandfather's technology -- a star drill and a 3-pound hand sledge.
What you want is a rotary hammer not a hammer drill (although some folks may use the terms interchangeably). Hilti, Bosch, Hitachi, Dewalt, Milwaukee, Makita all make them but as someone previously posted probably Hilti and Bosch are most common around here. If you're drilling (or more accurately rotary hammering) for 1/4" tapcons, an SDS or SDS+ tool is perfectly adequate. (Hilti uses a different name for SDS and SDS+ tools. I can't recall it right now). Many places will rent them if you'll have no further use for the tool after this one project.
You won't believe the difference between using a hammer drill and a rotary hammer. It's almost fun.
Rotary Hammer
I agree with the above poster that rotary hammer will be like a walk in the park. Just would like to tell you that putting all your weight on a rotary hammer defeats the purpose and in fact may hamper the process. Unlike a hammer drill where pressure is necessary, a rotary hammer does it's thing best when all you use force wise is enough to engage the hammer action. Let the bit and drill do the work.
I got a Bosch Bulldog to drill a bunch of 5/8x12" holes in concrete and have been very happy with its performance.
Roto-Hammer
CPO sells all brands of reconed tools. I just got a little DeWalt sds plus that also came with a quick change 3-jaw chuck. It replaced a smokeless Bosch hammerdrill, and there is no comparison. Lowe's sells Bosch sds bits for tapcons.
Maybe a dumb question, but - Are ya sure you have it in hammer drill mode?