Well, let's see. I passed quals. I have a thesis card. I picked a topic. I wrote a proposal. What's next?
I need a committee.
The rules are that I need at least three professors on the committee. The conventional grad student wisdom suggests that you want to keep it to as few as possible - because the more advisors you get, the more opinions you have to deal with, and the harder it is to schedule meetings. It may sound silly to worry about scheduling meetings, but it really isn't trivial to get a handful of professors in the same place for an hour. I've seen a couple people who almost couldn't graduate because they couldn't get their last committee meeting scheduled. And trying to schedule the actual defense is a real bear (although come on, who worries about that when you are two years away from that point?).
My own advisor is obviously member #1. I need two other professors.
My thinking is that I am researching several things - a manufacturing process, a precision machine design, and a new material.
I work in a lab for manufacturing, which has a whole bunch of professors involved, each of which have their own individual lab. One of the other professors in this lab specializes in precision machine design. My thought is that he would be perfect for member #2, because he covers the bases of both manufacturing and machine design.
I went to talk to this potential member #2, explained my plans for a PhD and asked if we could discuss any overlap with his lab's interests. Turns out a lot of the ideas I had for machine design are things that his lab has already tried (some worked, some didn't). At first I thought, well, beautiful! This has already been done! But perhaps not so beautiful - if somebody else has already done most of the novel machine elements I was going to design, maybe I need to pick something harder? Or maybe it will just make it a really fast PhD.... :) In any case, the professor actually offered to be on my committee. So, check! Moving on.
My ideal member #3 would have expertise in the fancy material I want to try, and also expertise on the applications of the devices I am making. Even though I am on the "making the chip" side of things, I need somebody on the "using the chip" side to advise me what they actually need. I might not be able to find someone with both of those qualities, in which case I might need a member #4.
I contacted two professors who are on the applications side, and asked if I could come visit and learn more about their labs. I met with both of them, and it was quite useful. I was able to get some good information on what the specifications for my machine/process should be, and what qualities they need from the finished product. They both confirmed that the problem I want to solve is indeed an important problem, which is good to know. One even said if I could do what I proposed, it would be "transformative." That's what I like to hear!
I didn't ask either one to be on my committee, because I'm not sure if a) either one is interested or b) which one would be a good fit for what I need. Of course, not that I'm entirely sure WHAT I need, since I haven't done the research yet... Neither of them have expertise on the materials side, so not ideal. I still have plans to meet with a couple other professors on the materials side. Maybe I'll get lucky and find my ideal member.
In any case, I'm 2/3rds of the way to a committee. That's enough accomplishment for one week.