Circling the Drain

Throwing a big bowl is the easy part. The tricky part began today: figuring out how the holes work with the plumbing. I have a sample drain pipe, with the little gasket thing that lets you fill the sink.

The outer dimension of the pipe is 1 5/16"; which means that the hole through the bottom has to shrink to larger than that in order for the pipe to fit through. The flange is 2" wide, which means the lip surrounding the hole has to shrink to at least that large. The spec for B-mix Sand is 12% shrinkage, plus or minus 2%. I had a momentary freak out when I saw that plus-or-minus business, but the tolerances must be...sufficiently tolerant, or no one would be able to make vessel sinks. SO. Assuming 13% shrinkage, because it's better for both hole and flange to be too large rather than too small:

• The hole I made 1 5/8"
• The lip around the hole I made 2 3/8"

I cut the hole once and had to fill it in again before I decided to make a run to the store for a compass. Things went much more easily then.

Gaah! I have to go turn up the bisque. I've been so engrossed in this project I forgot I was firing!