Drilling into a Concrete (council style) Slab - Cannot do it, help please.

Discussion in 'Builders' Talk' started by StevenUK, Jul 1, 2018.

  1. StevenUK

    StevenUK New Member

    Hi,

    I am attaching a pergola to a concrete base, onto the slabs, which are council style, 50mm or so thick.

    I have this as the drill:

    https://www.screwfix.com/p/dewalt-d...-cordless-combi-drill/899cf?_requestid=366354

    And this as the drill bit (14mm):

    https://www.screwfix.com/p/straight-shank-masonry-dril-bit-14-x-200mm/1550v?_requestid=366707

    And it is hardly making a dent in it, and if I try and force it, it will knacker the drill I feel.

    I did drill one hole yesterday, and it took around 20 minutes, and tried another one today, and it is hardly getting past 1cm deep.

    Can anybody please advise, as the missus is now getting impatient and wants this pergola put up, and I cannot even get into the concrete for the holes.

    Thank you in advance.
     
  2. jonathanc

    jonathanc Screwfix Select

    Sounds like an excuse to buy a new toy/ tool

    If you really want to drill into slabs then get yourself a mains SDS drill. Titan one is ok

    Else lift the slab and pour concrete: probably more stable anyway
     
    StevenUK likes this.
  3. PhilSo

    PhilSo Screwfix Select

    Start with a smaller drill bit

    PhilSo
     
    Heat and StevenUK like this.
  4. StevenUK

    StevenUK New Member

    I only just got the drill - cordless dealt one. Seems powerful enough, but just not drilling it.
     
  5. StevenUK

    StevenUK New Member

    Thanks I will try that, just seems like it is like drilling through steel.
     
  6. KIAB

    KIAB Super Member

  7. StevenUK

    StevenUK New Member

    Thanks everyone, I just made 4 holes starting with like an 8mm bit, and worked my way up to 14mm, and that seemed to do the trick, although discharged 2 x dewalt batteries doing it, but did it.

    One is a lean to pergola, so 'only' another 20 holes to go...

    I definitely appreciate the help!
     
  8. Astramax

    Astramax Super Member

    Do yourself a favour Hire an SDS drill.
     
    KIAB likes this.
  9. Sparkielev

    Sparkielev Screwfix Select

    The hammer action on your drill is far different to a SDS it sounds like it is screaming where it should sound like it hammering the drill bit in get a SDS drill
     
    Astramax and KIAB like this.
  10. WillyEckerslike

    WillyEckerslike Screwfix Select

    If this is truly 'council style' there's not enough of you (at least one should be permanently on his/her phone), a nineteen year old supervisor with 'disco shoes' should be in attendance and most importantly, despite your concerns you're still doing it too quickly.
     
  11. PhilSo

    PhilSo Screwfix Select

     
  12. HarDeBloodyHarHar

    HarDeBloodyHarHar Active Member


    Then when you come to build, cut your posts with a breadknife. keep going, you can do it!
     
  13. PhilSo

    PhilSo Screwfix Select


    Not at all amusing. Even though you think it is.
    Arrogance

    PhilSo
     
  14. PhilSo

    PhilSo Screwfix Select

    Obviously not sober :cool:
     
  15. WillyEckerslike

    WillyEckerslike Screwfix Select

    Having worked on both sides of the fence I speak from experience. And you're right. It's not amusing. It's outrageous. Couldn't wait to get out. Work ethic sucked out of you like a drip in reverse. In fairness it might not be as bad nowadays....

    Edit. It was meant to be funny so sorry if offence was taken.
     
    Last edited: Jul 1, 2018
  16. JustPhil

    JustPhil Active Member

    Whilst an sds is deinfitely the answer I’d have thought you should at least be able to get through a lot quicker than twenty minutes with a combi drill.
    I picked up on your comment in your OP “it will knacker the drill I feel” and I suspect you might be applying too little force. A hammer drill relies on hammering, and that requires force/weight behind the bit. Put your back into it, you have a good quality drill there that can take it.
    Masonry bits don’t cut by virtue of spinning - that causes heat in the bit and blunts them - instead it’s the hammer (like a masonry chisel) action combined with rotation which clears the debris.
    If you do get an sds on it you’ll be amazed at how easy it is though :)
     
    Astramax likes this.
  17. Heat

    Heat Screwfix Select

    Ordinary SDS masonry drills are not good at drilling very hard materials like high density concrete slabs. Those drills are designed to chisel into what is being drilled and that is obviously no use on slabs.
    What you need is to use sharp masonry drill bits starting with a small size and working up to your largest needed. A 5 or 6 mm bit is good as a starter.
    Even a good ordinary hammer drill will work well with a non SDS bit if it is a top quality drill bit used.
     
  18. rogerk101

    rogerk101 Screwfix Select

    Keep your drill bit cool by dipping it in a bucket of water.
    Masonry drill bits are made with hardened steel and one thing they do in the hardening process is shock cooling the metal to get it harder. Allowing it to cool down naturally undoes all the hard work the manufacturers did to get the metal hard.

    FWIW, I was so excited when I bought my first cordless combi-drill, but soon became disappointed by how poor they are at masonry drilling. I was so spoiled with my prior experiences with good corded drills that I now don't even bother trying drilling into bricks or concrete with my cordless drill. I still use my 30 year old Metabo or my 20 year old Makita corded drills.
     
  19. Heat

    Heat Screwfix Select

    I have a Hilti 22 volt combi drill and despite it being an average sized drill, it is easily capable of most masonry drilling for rawplugs etc.
    So it also depends on the quality of the cordless drill.
     
  20. Heat

    Heat Screwfix Select

    What combi drill did you buy?
    Got to pay decent money, but I have been surprised at how good the cordless are.
    Although for large diameter holes in concrete block walls the mains voltage drills are better unless you buy the best heavy type of combi.
    Ask some trades folk to let you borrow their combi to do a test drill hole.
     

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