Get a piece of 4x2 that is longer than the fork vertical and place the crown's base on top to create a crown race. After then, place the race on the fork and grab two smaller pieces of wood. Hold them in one hand, one on top of the other, with the steerer in the middle. Using a hammer, gently beat the ends alternately. Because the wood deforms before the metal race, it will seat the race precisely without warping.