Answer: The type of wood used for the spindle and hearth board is crucial to making an ember. This is an often overlooked fact in many descriptions of making fire by friction.
What you are trying to do is create a very fine wood dust and then heat it to between 371-426°C (700-800°F). When that occurs, the wood dust starts to glow and it forms an ember much like the tip of a lit cigarette. That glowing ember can then be coaxed into a flame by adding it to a bundle of very dry tinder and blowing.
There are several ways to try to accomplish this; bow drill, hand drill, fire plow, or fire saw. They all have one thing in common. The type of wood used is crucial to making an ember. It comes down to the quality of the wood dust formed during friction and the ability of the wood to retain the heat where the dust is forming. Low density woods (softwoods) don’t transmit heat as well as hardwoods and therefore they keep the heat concentrated near the wood dust.
Storm from Primitive Ways has personally made hundreds of embers by method of the hand drill using various combinations of wood. He has created a chart of the combinations (PDF) and the effort it took to create an ember (if it was possible at all). It is important to note that not every combination of wood will successfully create an ember. So if you are not having success it could be that the combination of wood you have chosen won’t work.
Storm's guide to using the hand drill should get you started http://stoneageskills.com/articles/handdrill1.html