The granite guy I use cuts 'keyhole' type slots at the edges oft he sink cutout that hold the head of a 1/4-20 bolt.

A slot about every 6 to 8 inches or so, but at least as many as you would use to anchor the sink to a wood type substrate.

Regular sink clips are then used with a washer and locking nut (nylon ring type).

Slide the bolt heads in, slide the sink up into position, block it there temporarily, install clips, washers, nuts, tighten nuts.

The only other way i wold ever consider would be wood framing or angle iron supported by the cabinet.

A water filled sink is heavy.

Water is over 8 pounds a gallon, around 64 pounds a cubic foot.

Then add in the sink contents and maybe a GD.

The water usually dominates, then the GD.

Our fabricator siliconed the sink to the underside of the countertop and installed shelving brackets mounted to the cabinet walls to support the sink bowl.
Here's how it looks.
Right side.

willtv - is that the normal way to anchor a sink that is almost the width of the cabinet? My new sink will have maybe half an inch clearance on either side of the cab inside, and I've been wondering how it would be anchored.

judibean, To my knowledge there is no "normal" way to mount a sink.
I've seen several diffferent schemes for supporting an undermount sink.
The method my fabricator used seems to be quite sturdy.
When I'm scrubbing difficult, burnt on food from my pots & pans, I lean on them pretty hard and in the 2+ years since the installation, I haven't detected any movement.
There is also a device called a sink setter which many folks on this forum have used and been very satisfied with.
I'm attaching a link.

Here is a link that might be useful: Sink Setter

Thanks! That's pretty helpful!

Don't know if this is right, but it's held for 10 months now (after sink fell after 11 months!) Kind of an after the fact sink setter:

I am a fabricator.

there are many ways to mount a sink.

The "T" slot method described in the original post is called "T-31". It was originally designed for hanging slabs on the sides of building and is a very good mounting system. We have NEVER had a sink so mounted come loose.

other methods include framing the sink with wood strips attached to the cabinet. This is done sometimes when the sink is overlarge for the cabinet (happens a lot) and there is no access space for the T-31's.

Visit "Granquartz" or "BraxtonBragg" websites, both distributors of tooling and supplies for fabricators, and you'll see a variety of mounting methods.

IMNSHO (in my not so humble opinion) the T-31 system is best when it can be used.