Conventional fiber elongation method for glass viscosity determination suffers from the requirement of a rectangular temperature-position profile with a width of L0, or alternatively a prescribed temperature-viscosity relation. Recently, Boyd et al., has largely suppressed this drawback results from L0 by replacing the furnace with a CO2 laser in the conventional fiber elongation measurement. However, such a CO2 laser setup is complex and cost-intensive. We present a new method to overcome this drawback on a simple glassmaker-lathe with a micrometer and the corresponding mathematical transportation from the equation used in traditional fiber elongation method. Additionally, some improvements have been made in our new method, i.e. a fiber force Bragg-sensor (FBG) is applied.