Shoemakers use a bunch of nominal points and lines on feet, lasts, and shoes when designing and talking about footwear.
Back Height
point on the heel of a last, along the main axis, above the counter point
frequently set at some fixed allowance above the counter point, such as 10mm or 7mm
Breast Line
nominal line along the bottom of a last showing the intended location of the heel breast
often corresponds to the front edge of a heel-only last plate
Counter Point
point on the heel of a last, along the main axis
often calculated as one fifth the standard last length, plus some allowance, for example 3mm
Instep Point
point on a last marking the intended height of the quarters over the instep, or the height of the facings
Main Axis
AKA: Center Line, Center Axis
a line on a last running from the featherline of the toe up the center of the instep, over any vent, the cone, and any thimble, then down the center of the heel to the featherline again
Modern lasts are not symmetrical, so the location of the main axis through the toe is open to some interpretation. Some sources prescribe drawing through the center of where the tip of the second toe will lie in the shoe. In practice, the main axis often determines the line of symmetry for symmetric patterns, so appearance and sufficient lasting allowance affect where it’s drawn.
Toe Point
point along the featherline of the forepart of a last showing the furthest where the toe extends furthest from the heel
used to measure standard last length and stick length
Tread Point
nominal reference point on the crown of a last—the bottom of the forepart—where the joints will fall and where the shoe will bend during walking
Different makers position the tread point in different ways:
- where the main axis intersects the treadline
- where the joint of the big toe falls
- where the joint of the first (index) toe falls
Vamp Point
a reference point along the main axis of a last, often denoting where the top of the vamp stops and the quarters or tongue begin
Vamp points are located in a number of different ways, by different makers and for different styles.
Some place the vamp point where the line connecting the medial and lateral joints, which is to say the line along which ball girth is taken, crosses the main axis.
Significance
Clear the Ball of the Foot
For many styles, the vamp point sets the minimum practical length of the facings.
Since the foot is usually wider at the ball than at the waist, and a shoe should usually conform around both of those parts of the foot when securely fastened, the waist of the shoe needs to expand to allow the forefoot to slip through. The facings do this by spreading out when unfastened. The vamp, on the other hand, has a fixed girth. The facings must therefore continue close enough to the ball of the foot to accommodate the foot’s ball girth, much as the pass of a slip-on boot accommodates short heel and long heel girths.
Avoid Interfering with the Joints
On the other hand, facings that cross the crease may interfere with the flexing of the forefoot and the bending of the shoe during walking.
Some styles, such as lace-to-toe, do this intentionally. Monkey boot facings often continue past even to the very tips of the toeboxes.