Drilling knockout for Composite granite sink

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by livingaboard, Mar 2, 2007.

  1. livingaboard

    livingaboard New Member

    Messages:
    8
    Location:
    California
    Once again I call upon the vast knowledge of this board to help me out.

    I ordered a Blanco composite granite sink and forgot to have them drill an additional hole next to the center hole it comes with. It is on its way and I will need to open up an additional "knockout". There are 7 knockouts on this sink. Are these "knockouts" really knockouts or are they just a premarked area that have to be drilled out?

    If I have to drill a hole how should I go about doing this? I believe it is about 1.25 inches in diameter.

    thanks,

    Dave
  2. coz

    coz New Member

    Messages:
    91
    Location:
    MA
    you should have directions for knocking out the holes with the sink . if not get them. do not drill them
  3. coz

    coz New Member

    Messages:
    91
    Location:
    MA
  4. If they have stickers on the finished side of sink showing locations of the holes,


    don't assume those stickers are directly over the knockouts. I installed a moenstone sink last week, was working tired and started pecking on the knockout sticker like the first one I did and had no problems.

    Turns out the sticker was off an 1" and all those pecker marks could of cost me a $600 sink no one wanted.

    Pulled the sticker off, used a 1-3/8" carbide hole saw and centered it over all the dings I put in the sink and took care of the mishap.

    Never again will I trust the sticker locations.
  5. livingaboard

    livingaboard New Member

    Messages:
    8
    Location:
    California
    thanks

    Thanks for the information. I was just trying to think ahead as to what tools I would need if I had to drill. Contacting Blanco was my next step but I figured it would take a while for them to get back to me.
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    If I am correct, the blanco sinks are a composite similar to Corian? These can be drilled with any hole saw. IF it is really a granite composite like Silestone, these need more serious tools.
  7. livingaboard

    livingaboard New Member

    Messages:
    8
    Location:
    California
    composit

    They are made of 80% granite with the rest being essentially a resin or plastic.
Similar Threads: Drilling knockout
Forum Title Date
Plumbing Forum, Professional & DIY Advice Core drilling Apr 16, 2012
Plumbing Forum, Professional & DIY Advice Core Drilling and Floor Drain Question Aug 31, 2011
Plumbing Forum, Professional & DIY Advice Need Advice on preventing drilling into Water Lines - Grab Bar Installation... Aug 29, 2010
Plumbing Forum, Professional & DIY Advice Horizontal drilling/boring Jan 23, 2010
Plumbing Forum, Professional & DIY Advice Help drilling joist Dec 18, 2009

Share This Page