Not a crucible! Must automate steel! Unless... has someone come up with a way to automate steel production in a crucible?
I've been using a very lazy solution for a rather long time - basically put 10 carbon in a crucible, and then put 500 iron in the hopper above crucible. And then just point myself at the single mold and put something heavy on the right mouse button :).
Even though now I have a somewhat universal auto-smelter, sometimes it takes wrong amounts of materials, and I still don't know exactly why. The funniest part is that I have to use an Excel document to calculate the values for hoppers and thermo-sensors