Drilling a cast iron soil stack

Discussion in 'Plumbing and Central Heating' started by Bilabong007, 30 Jul 2017.

  1. Bilabong007

    Bilabong007

    Joined:
    25 Apr 2007
    Messages:
    214
    Thanks Received:
    26
    Location:
    Glasgow
    Country:
    United Kingdom
    Hi,

    My father has a blocked cast iron soil pipe where it exits the house. I was hoping to drill a hole in this and clear the blockage (10-15mm hole required). I have a pipe cleaner for a pressure washer that I can poke in then seal the hole afterwards.

    What bits should I use? Speed? Lube?

    If it cracks were taking apart a bathroom... If it doesn't work we're taking apart a bathroom... One of those ones

    Many thanks

    Graeme
     
  2. Sponsored Links
  3. Burnerman

    Burnerman

    Joined:
    7 Feb 2008
    Messages:
    23,222
    Thanks Received:
    4,509
    Location:
    Northumberland
    Country:
    United Kingdom
    There shouldn't be any real issues when drilling cast iron, but the outer 'shell' maybe somewhat tougher than expected due to the chilling of the casting.
    Use HSS drill bits, centre punch the position before you start. Lubrication won't do any harm - a spray of Duck Oil or whatever.
    Drill using a series of bits - maybe 4mm is a good start, working up to the size required. Drill bits up to 13mm are common enough to get, larger ones more difficult but Toolstation so them with reduced shanks which will fit a typical 13mm drill chuck.
    John :)
     
    • Thanks Thanks x 1
  4. DaveHerns

    DaveHerns

    Joined:
    11 Nov 2009
    Messages:
    2,582
    Thanks Received:
    207
    Country:
    United Kingdom
    Centre punch it gently!
     
    • Thanks Thanks x 1
  5. Nozzle

    Nozzle

    Joined:
    23 Dec 2012
    Messages:
    2,240
    Thanks Received:
    297
    Location:
    Suffolk
    Country:
    United Kingdom
    Centre punch it very gently - or not at all, use a burr in a dremmel. You don't need any lub as the graphite in the cast iron works as a lub. Check for over-heat as you drill though, but I don't think it'll take that long to go through. Start off with a pilot hole.

    Nozzle
     
    • Thanks Thanks x 1
  6. dpsservices

    dpsservices

    Joined:
    22 Dec 2008
    Messages:
    500
    Thanks Received:
    26
    Location:
    Northamptonshire
    Country:
    United Kingdom
    Does the soil pipe not vent through the roof ? If so I'd be more inclined to try and clear the blockage from there with proper drain rods. Or try plunging the toilet with a wick mop when the toilet bowl is full of water. Regards david
     
    • Thanks Thanks x 1
  7. Bilabong007

    Bilabong007

    Joined:
    25 Apr 2007
    Messages:
    214
    Thanks Received:
    26
    Location:
    Glasgow
    Country:
    United Kingdom
    Many thanks for all the advice. Excellent as always.

    I selected the drilling position based on planting the drill on the ground. It meant I just had to control it left to right as it started. From then in it was easy to apply even pressure.

    Cobalt bit was very slow.
    New hss was easy with low pressure and slow speed. Spray of lube to be sure.
    Expanded a 4mm-8mm-10mm but it was too small. Enlarged that with an aldi cheapo hss step drill to about 15mm. Needed a lot of pressure and slow speed.

    2hrs thinking about it and 10mins to do it lol. Still it worked and I unblocked the pipe in 5 mins then put a rubber bung in the hole for future access.

    Thanks again

    Graeme
     
    • Like Like x 1
  8. foxhole

    foxhole

    Joined:
    14 Mar 2006
    Messages:
    18,213
    Thanks Received:
    2,091
    Location:
    Kent
    Country:
    United Kingdom
    Bottle of 'one shot' would have done it without the need for drilling.
     
  9. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
  10. Sponsored Links
Loading...

Share This Page