A method of producing an elongated component of glass, said method comprising heating a bulk glass component in a heating region at a temperature; drawing a strand from the bulk glass component at a forming region of the bulk glass component; using a pulling device comprising a motor configured to exert a pulling force on the strand to control the rate at which the strand is drawn from the bulk glass component; characterized in that the pulling device is configured to exert a pulling force on the strand in both a direction aligned with a gravitational force and a direction opposite the gravitational force, wherein determining the pulling force (F p) applied to the strand by the pulling device comprises: (i) measuring a voltage applied to the motor of the pulling device, measuring a torque applied by the motor to wheels; and calculating the pulling force (Fp) from the voltage and the torque, or (ii) measuring the output of load cells applied to the pulling device, determining the mass of the strand based on the cross-sectional area A and the density p and the length L of the strand, calculating a holding force (F h) applied to the strand by the forming region by determining the algebraic sum of the gravitational force F g and the pulling force F p applied to the strand, wherein the gravitational force F g is calculated using the determined mass of the strand; and determining whether the holding force (F h) is equal to a desired holding force (F h) based on a desired viscosity of the forming region; and adjusting the temperature of the heating region if the holding force (F h) is not equal to the desired holding force (F h). heating a bulk glass component in a heating region at a temperature; drawing a strand from the bulk glass component at a forming region of the bulk glass component; using a pulling device comprising a motor configured to exert a pulling force on the strand to control the rate at which the strand is drawn from the bulk glass component; characterized in that the pulling device is configured to exert a pulling force on the strand in both a direction aligned with a gravitational force and a direction opposite the gravitational force, wherein determining the pulling force (F p) applied to the strand by the pulling device comprises: (i) measuring a voltage applied to the motor of the pulling device, measuring a torque applied by the motor to wheels; and calculating the pulling force (Fp) from the voltage and the torque, or (ii) measuring the output of load cells applied to the pulling device, (i) measuring a voltage applied to the motor of the pulling device, measuring a torque applied by the motor to wheels; and calculating the pulling force (Fp) from the voltage and the torque, or (ii) measuring the output of load cells applied to the pulling device, determining the mass of the strand based on the cross-sectional area A and the density p and the length L of the strand, calculating a holding force (F h) applied to the strand by the forming region by determining the algebraic sum of the gravitational force F g and the pulling force F p applied to the strand, wherein the gravitational force F g is calculated using the determined mass of the strand; and determining whether the holding force (F h) is equal to a desired holding force (F h) based on a desired viscosity of the forming region; and adjusting the temperature of the heating region if the holding force (F h) is not equal to the desired holding force (F h).