Disposer flange and sink basket in cast iron sink

[dabiz7]

Ok, here is a newbie question for you, be gentle !

Am installing a Kohler cast iron sink, replacing an old stainless sink. Currently, I have an In-sink-erator garbage disposal on one side, regular sink basket drain on the other bowl. I want to keep this same arrangement on the new Kohler sink, but my question is:

The hole(s) in the bottom of the cast iron sink have a large, curved radius lead-in to the hole. I am just now noticing that the other sainless sinks I am looking at have a rather flat area where the flange seems to mate up with nicely. However, I am noticing that the disposal flange and the Kohler sink basket flange both have quite a right angle underneath the flange, very small radius. This really seems a little strange when I set these in the hole. Am I supposed to be using a special flange for the disposal and basket mounting?

I have looked high and low for a special flange, no one seems to make one. I can only assume that this means that all the parts out there must work.

So, I guess load up the underside of the flange with plenty of silicone before installing and completely remove the excess after tightening the nut underneath?

[Redwood]

Actually the only thing you have wrong is loading the flange up with Silicone RTV. Your Kohler cast iron sink is a good one and will probably outlast several disposers. You may want the option of removing the flange and using a nice new shiny one off one of your new disposers at sometime. Despite what the Silicone RTV users claim it does have very strong adhesive properties making removal a bear of a job.

The cast iron sink is much thicker than a stainless sink and the flange will fit. However, if you are using the Insinkerator style flange with the snap ring I would recommend a second person to push down from the top while securing the ring. It can be a lot of fun to do alone there is very little room left.

[hj]

It can be a lot of fun to do alone there is very little room left.

That is why I have an ISE snap ring installing tool. It is helpful with stainless steel sinks, but INVALUABLE with cast iron ones.

[Redwood]

That is why I have it too!
Joe Homeowner DIYer however probably will not have it...

[hj]

And by the time he does get it installed, even with a helper, he is going to curse the day his "decision maker" decided she wanted a disposer.

[dabiz7]

Sooo, plumbers putty instead of silicone? I think the instructions with the basket says plumbers putty, but I thought it tended to dry out and crack?

[Mikey]

That is why I have an ISE snap ring installing tool.

What? A tool I don't have? I've installed and un-installed ISE disposers on SS, CI, and manufactured stone sinks, and never felt the need for another tool. What am I doing wrong? Or right?