I designed, machined, assembled and tested this chemical ionization electron impact ionizer for a quadrupole mass spectrometer.
304 series stainless steel, nickel screen, machinable ceramic, vespel (properties similar to teflon with less outgassing.) and ruby sapphires.
Our average hardware was 2-56 in that unit and they were assembled absolutely dry so it didn't contaminate the ultrahigh vacuum chambers they were used in for sample testing.
The cleaning process involved eighteen steps beginning with a light percentage phosphoric acid soap scrub to a final bath in heptane after a dance thru the various specific gravities in the solvent list that were done to remove any contaminants.
Cleaner than clean and 304 screws in 304 holes was gall city for sure.
Every blind tapped hole had to be cross drilled for ventilation and there were reamed fits all over it.
