Is the length of the dowel pin determined by a ratio of the diameter?
On the small end of the scale you have a 5mm X 25mm pin which equates to a 5 to 1 ratio. On the large end of the scale you have a ⅝ X 5″ pin which equates to an 8 to 1 ratio. Generally speaking, the length of a dowel corresponds to a different formula. This is determined by how much dowel can be inserted into the shortest member of the two piece joint. Twice this length is a common rule of thumb for determining dowel length. As an example, if your shortest member is 1″ thick and you know your safest drilling depth is ¾” then a 1½” dowel should be used. A 1½ length equates to two times the ¾” thickness. A similar procedure can be used to determine a proper diameter for the dowel. Generally, there should be no space smaller than half the diameter of the dowel between any edge of the dowel and the outer edge of a panel. For example, if the side panel is 1″ thick then you want to use a ½” dowel to adhere to this rule since that leaves ¼” on each side of the dowel. Please keep in min
