Simply use a lower setting if the desired result is not achieved. The distance setting is cumulative from stage to stage. A setting of 2.0 in the first stage, and 4.0 in the second stage, will stop the carriage at 4 mm., not at 6 mm. The carriage moves from 0 to 2 in the first stage, and from 2 to 4 in the second. A lightweight, low inertia coil carrying a preset constant current and positioned in a strong field of a permanent magnet provides the pulling force to draw out the glass tip.
Stronger forces produce faster tapers, smaller tips, and thinner walls at the tip.
For most programs requiring multiple stages, force should be decreased in middle stages, when the glass is thinner. Use strong force in the last stage, after cooling, to break the glass for larger tip diameters. The APP-1 uses a temperature sensor and feedback control rather than simply constant current. Constant current produces different temperatures as the coil ages and its impedance changes. Higher heat settings produce thicker pipette walls at the tip, longer tapers, and smaller final tips.