Hi,
I drilled my own holes for my air switch in my soapstone. The carborundum-encrusted drill bit did a good job, and the standard-issue insinkerator switch dropped right in.
I wonder if the original installer used a metric (30mm) bit which squeeked by with the old switch.,
It's not difficult to enlarge a hole. I would make a template (with the new hole size drilled into it) from a scrap of plywood, and hot-glue it down to the C-top over the existing hole. Then introduce the proper sized bit to the the soapstone. When you have 1/4" of the hole drilled you could snap off the template and finish drilling, but you could as well leave it until you're done. Use a slow-speed drill, and water is not needed, but you can use it to keep down dust. Probably easier to wet it with the template off.
Lowe's sells a nice cheap 1 1/4" carborundum bit.
Casey

I agree with Sombreuil that you should be able to do this yourself. I put some holes in my granite and a good diamond hole saw cuts through like a hot knife through butter.

1 1/4" diamond hole saws can be had from Amazon or your local hw store for about $15 and, as Sombreuil says, if you go slow and take your time you should be through in no time. I think the suggestion of using a template is a very good approach.

Personally I would use water just to keep things lubricated, cool and mitigate dust. Just a little squirted on at a time should do it.

How about attaching a picture so we can see? I don't really see how you could crack the stone unless there is very little support around it. Even then, the bit is cutting the stone, not stressing it.

-Stooxie

I totally agree with the above 2 answers, I have cut ceramic and granite as well as marble with carborundum or diamond bits/blades. For sure use the template as the hole is already too big to rely on the pilot bit, the hole saw would just walk and ruin your counter top. Also water in a spray bottle to cool and supress dust is a must, but this is really a simple task that any reasonabley handy homeowner can do by themselves.

What brand was the old switch?

There is a fiber optic switch that uses a 3/8" hole that will surely fit. Might be too small to cove the entire hole as I don't know what dia. the button's flange is.

They make an adaptor for 1 1/4" hole that might be easily modified to fit your slightly smaller hole.

Here is a link that might be useful: optic switch

Thanks so much for your replies. Since neither my husband nor I are even remotely handy with tools - and since I'm deathly afraid of damaging our countertop - I'm going to look into the fiber optic switch. Looks like that might be a good solution!

It (air swt.) may need some fooling with to use. It'll be easier to deal with its plastic than the stone top though.

So I bought the fiber optic switch with the adaptor, and the adaptor is too big for my hole. Darn. But it looks to me like I should be able to just put a bead of silicone on the button to fasten it to the countertop, and it should work just fine. Is this possible? I'd really like to give my husband a working garbage disposal for Christmas.

posey - I thought the flange might have been a bit big, see above post.

What's it made of? Can you file or sand down the edges of the holder to make it fit?

You can use silicon on the button but you have to make sure it and the counter are clean first. No soap , oils ect...

Use RTV silicone .

Is this the FO unit made by Waste King? I have a couple of them for my two Insinkerators and IIRC the button is about an inch in diameter. This implies that some type of flange is needed to overlap your inch and a quarter hole. This flange could be made of stone, corian, colored plastic, stainless steel, whatever. It would be bonded to the counter using silicone.

This flange would have a hole in it (I forget the required size but it was in the vicinity of a half inch -- see the FO directions) that the FO button mounting extension would fit into. The provided mounting hardware should work with this flange, once you have someone fabricate it for you.

kas

A late thank you to all who posted here. The fiber optic switch works like a charm. After trying - and failing - to jury-rig an adaptor, I just fastened the button to my countertop with some museum wax and installed it as-is. Great to have a garbage disposal again!