Cutting a rectangular undermount sink

[MartinTravels]

I am getting ready to do my first ever granite countertop install.  I've ordered and watched all three of the DeFusco Granite videos.  The video on the undermount sink is great...except it shows an oval cutout and my kitchen sink is rectangular.

How do I make a rectangular sink cutout?  Do I plunge cut it with a skilsaw running against a straightedge?  I want the cutout to be perfectly square and straight.  What about the corners of the cutout?    Should I do sharp corners or slightly rounded corners? 

Any input would be appreciated.

Thanks,

--Andy
Monroe, WA

[Mark D.]

Do the straight cuts as in dvd #33 but do not connect the corners. leave them short. Take a grinder with a granite turbo blade and connect the adjacent cuts with a plunge cut at 45 degree angle the both of the adjacent Skilsaw cuts.
When you are finished you should have a rectangle with truncated corners (a shape made of 8 straight lines).

Now take a brazed grinding drum as in dvd # 2 and grind the area that will be the corners back into the rounded shape you want. Here is the tool I used in dvd # 2, although smaller diameter ones are available:
http://www.defusco.com/x58%E2%80%9D11-brazed-drum-bearing-medium-p-2093.html
Make sure your cutout is smaller than the inner diameter of the sink so there is some overhang of the stone over your sink once installed.

Then polish to a finish. If you have any questions call me at 800-289-6834.

Glad to be of service,
Mark