Fisher pattern, four fin aluminum draft, control knobs feature, a steel nut Posted on 01 Jun 16:00

       Please note that our original Fisher pattern, four fin aluminum draft, control knobs feature, a steel nut as the bearing for longer thread life. The issue that draft knob customers were faced with is that aluminum draft knob threads do not last as long as steel or bronze threads around heat. 

       Our Bronze draft control knobs are made out of solid silicon bronze I.E. silicon bronze threads are a better longer lasting bearing at higher temperatures than aluminum threads can ever tolerate. Silicon Bronze or Statuary Bronze, as it sometimes called, is 92% copper 4% zinc 4% Silicon ( Silicon is glass ) The glass helps to keep the molten copper, base clean and fluid, at elevated casting temperatures. Silicon Bronze has the strength of medium to mild carbon steel and is one of the alloys that are recommended for bearings .