Friday, 3 January 2014

Using a (professional) core drill for the first time

Core drill on a stand
Sometimes a handyman needs to drill a large diameter hole in his walls and his hole saw does not do it. Large diameter ones can be found in some specialised shops but even so, they will be hard to handle and keep straight.

You should also realise that the torque needed by these large hole saw is definitely beyond the specifications of your (regular/professional) drill and that it is going to overheat fairly quickly... especially as you get deeper in the wall.

Core drills are much more expensive than drills and can either be handheld or come with a stand and usually have a pipe for water cooling reasons. Unless your going to frequently drill large holes and want to make your house look like Swiss cheese, renting is usually much more interesting than buying (unless you buy it used and sell it again after using it).

There are a couple of things I wish I new before I rented this machine.

Wall mounted core drill

  • You need to be two, period. This is not going to work if you're alone.
    I had to call my friend (on the picture) for help. It is also helps to have good friends... (or at least one)
  • You can use a normal drill to 'feel' where there might be concrete in you walls. Remember that concrete can mean load bearing... would you want to drill in there?
  • If you need to attach your drill, make sure you know how to us your wall plugs. Make sure you know how to use them properly.
    I got four metallic ones that are supposed to be hammered in a 12mm hole. Once plugged in, you need to use a metal stick to hammer the inside of the plug to make it open inside the wall.
    I failed to do this a couple of times and the plug came out during the drill...
  • You don't need to use water if you're working with soft walls (plaster, brick, cement bricks...).
    I even inadvertently drilled through a little concrete and everything went fine. You should however be aware that drilling hard walls without cooling will heat and reduce the life of your tool.
The drill is complete, seen from the other side
See that dust floating around?
  • Do not overtighten wall mounting screws. Doing so might make your wall plug spin inside the wall and weaken the whole thing.
  • Core drills are noisy and make quite a lot of dust. Make sure you wear a mask, glasses and ear protection. I also recommend building a 'kill room' (reference from Dexter ;-) using a sheet or tarp. This will keep the dust contained around the place you're working.
  • When drilling, do not turn the handle too fast. This will cause stress to the motor of the drill and put unnecessary stress on the wall plug.
    The drill I used had a gauge at its back. If your wall is soft, you should stay far off the 'red' side. I went too hard a couple of times and the wall plug got loose. This is one of the occasions where you're happy to have help from a friend...
  • In some older buildings as this one have a gap in the middle as insulation. Remember to continue drilling at least 10cm (?) further if you feel you are through. For that very reason, also make sure you never move the drill forward and avoid ripping the wall plug off.
  • Always make measurements of your wall from inside the hole you drilled. You rarely get the occasion to see your wall from this angle and you never know when the wall depth, insulation thickness (or lack thereof) might come handy. You should also take a couple of pictures of inside the gap (if you have one).

The end !