There are several practical considerations beyond the smoothness and heat resistance of your hole, such as the fact that it had better be waterproof; most of the Earth's land is opposite sea on the other side of the planet.
Secondly, you do not mention where exactly this hole is to be. If it runs from pole to pole and we ignore air resistance (which is a nonsensical thing to ignore in this context; while you are thinking about such questions, ask yourself what the air pressure would be like near the middle of the hole! This, by the way, is a tricky problem in calculus...) Then you would fall straight through, reach the other end, or nearly, and fall back again. In practice of course neither you nor the hole would get anywhere near the centre.
If the hole does not go from pole to pole, and in particular if it goes anywhere near the equator, then you would get severe effects of the Coriolis type. The planet is rotating, remember? As you get nearer the centre, even within a couple of kilometres of the surface, you will find that your angular rotation round the centre of the Earth speeds up drastically. Unless you and the hole (and the air in the hole) happen to be fiction proof, you will skid down one side of the hole and leave little more than some scorch marks and smears.
Don't do it.
That's my advice, but of course no one listens to me!
Cheers,
Jon
