member 22 when die member 22 is assembled in body 10 as shown in fig1 the tapered external surface of the die member mates with first portion 16 of the axial bore of body 10 and the front end of the die member is substantially flush with or recessed slightly within front end 12 of the body die tip 26 has a through axial bore of constant diameter typically a few thousandths of an inch larger in diameter than filament 28 such as an electrical wire or optical fiber which is drawn through the apparatus for coating cylindrical tip 30 having a diameter which is less than that of cylindrical bore 23 of die member 22 is positioned at the front end of die tip 26 the body of die tip 26 includes a front portion 32 which tapers outwardly from tip 30 to rear portion 34 which tapers inwardly from its junction with front portion 32 toward the rear end of die tip 26 tip holder or core tube 36 has a through axial bore with a first portion 38 which tapers inwardly from the front end toward the rear at the same angle as the taper of portion 34 of die tip 26 and a rear portion 40 of constant diameter i e a cylindrical bore the external surface of tip holder 36 tapers outwardly from the front end toward the rear for a first portion 42 of its axial length first portion 42 adjoins a relatively short cylindrical portion 44 annular groove 46 extends about tip holder 36 between cylindrical portion 44 and a second portion 48 of the axial length of tip holder 36 the exterior surface of portion.