VCarve calculates the depth of cut based on the width of the cut and the angle of the bit. Therefore, a 60 degree bit will alway carve the same letter deeper than a 90 degree bit. The smaller the bit angle, the deeper the cut. As a basic idea, think of the bit width as being narrower than the character width. The bit will plunge down until the sides of the V of the bit match the width of the character. If you have two 0.5 inch bits, one a 90 and the other a 60, the 60 will go deeper than the 90 trying to plunge until the letter sides are contacted. If you want a shallower cut, try a 120 degree bit, or use the flat depth option. You can check the depth of cut by hovering the mouse cursor over the preview. The bottom right of the screen will display the x, y, and z.