Patent ID: 6998087

Claim:
A layered deposition method for building a three-dimensional object comprising the steps of: providing a first thermally solidifiable modeling material to a first dispenser, the first dispenser having a first dispensing tip which has a downward planar face; providing a second thermally solidifiable modeling material to a second dispenser, the second dispenser having a second dispensing tip maintained in a fixed vertical position relative to the first dispensing tip, the second dispensing tip having a downward face approximately co-planar with the face of the first dispensing tip; dispensing roads of the first material in molten form from the tip of the first dispenser onto a base contained in a build environment having a temperature lower than an extrudate temperature of the first and second material, while moving said first dispensing tip in a predetermined pattern within a layer above the base; dispensing roads of the second material in molten form from the tip of the second dispenser while moving said second dispensing tip in a predetermined pattern within the same layer; and controlling the dispensers such that a trailing one of the first and second dispensers lags behind a leading one of the first and second dispensers by no less than a minimum transit time Δt, defined as the time for a road deposited by the leading dispenser to sufficiently shrink due exclusively to cooling so that the tip of the trailing dispenser does not drag across and smear the road.