Universal stem mold for manufacturing a molded glass stem

In an apparatus for manufacturing a glass stem for an electron tube having a plurality of lead-in conductors of different internal lengths and a plurality of fillets, said lead-in conductors extending through said fillets, there being at least one dummy fillet without a lead-in conductor extending therethrough, said apparatus comprising a first stem mold assembly and a second stem mold assembly for forming said stem therebetween, said first mold assembly including a plurality of lead-weights and a mold block having a first surface and an oppositely disposed second surface with a cavity formed in said second surface of said mold block, said mold block having fillet forming means therein, a lead-weight translator disposed within said cavity, said translator having a first surface and a second surface with a translator recess formed in one of said surfaces and a plurality of lead-weight apertures extending from said translator recess through the other surface thereof, and holder means disposed within said translator recess, said holder means having a plurality of apertures therethrough, the improvement wherein said first stem mold assembly comprises:

• a universal stem mold having a plurality of longitudinal fillet-forming openings formed through said mold block and aligned with said apertures in said holder means, and
• a plurality of inserts, each of said inserts being replaceably disposed within a different one of said openings in said mold block and within said aligned apertures in said holder means, each of said inserts having a shank portion and a shoulder portion, said shank portion having a first end and said shoulder portion having an oppositely disposed second end, said first end of each of said inserts having a recess provided therein with a lead-accommodating opening extending through said inserts and terminating in a lead-stop, said shoulder having a diameter greater than that of said shank portion to prevent said inserts from passing through said apertures in said holder means, said second end of each of said inserts being in contact with a different one of said lead-weights to retain said inserts within said apertures in said holder means.