Kitchen sink wobble

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twigpig

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I went to install a full size Kohler cast iron top mount self rimming kitchen sink on a granite slab. It wobbles from one corner to the opposite corner by about an eighth of an inch. I called the plumbing supply place I bought it and at first they were going to exchange it for me. Then they called Kohler. Kohler told them that they do not exchange unless the wobble is more than a quarter of an inch. My goodness. Can't Americans make anything well?!!!!!
My concern is that most of the weight will be on the preassure points of the two corners that will be in contact with the granite slab. I am afraid the granite will crack. I know the caulking will absorb and distribute some of the weight but with a sink this heavy I am sure the sink will sink through the calk and make contact with the granite at only two points. Has anybody used a grinder to grind a sink flat? How about if I put a small rubber washer under the contact corners or some other shim so there wont be metal to granite contact?

I went with Kohler because I was told it was the best. I like the top mounted sinks because they are easy to keep clean and you don't have to worry about them falling off the bottom of the slab.
 

Terry

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I don't remember installing many sinks that don't wobble some.

That's what caulk is for, well at least part of what it's for. It's mainly to stick it down so it doesn't move around and seal the water from going into the cabinet below.

Your sink is not the first one that moves.
I'm sure you will see years of use out of that sink and countertop.
 

hj

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sink

Once the caulk has hardened the sink is not going to "sink through it". It is not a question of making things right, it is a physical thing that when the cast iron is heated to apply the enamel, (you wouldn't want it painted would you?), and then cools it warps as any thick heated metal would. There is no way to keep it from warping, you just have to decide how much warp you can live with.
 

Prashster

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If there's significant wobble, the caulk will stress too, compromising the water seal.

I'd shim it.
 
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Cass

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You can shim it in the back where it can't be seen.

The caulk will support the sink.

If you want, shim and allow the shim to stick out. Caulk and allow the caulk to dry a day or so and then pull the shim and caulk the shim hole.

Do this all in the rear of the sink.
 

Plumber1

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calk

Bring back the Hudee.

Cut it close and calk seems to be the prevailing method.

Is cheaper better?
 
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