So your friend says the smaller the bit the better? Sorry, but I couldn't disagree more. The angle of the cutting tip of your bit allows you to set the width of the cutting path by setting the depth of the bit. Mine have 90� angles and allow me to set the cutting path width from 0.008" (0.2 mm) to 0.012" (0.3 mm). I can use smaller bits that go as fine as 0.004" (0.1 mm) cutting path, but I never use them. If I needed to I would, but frankly I've never needed to.