Stay and fork vent holes necessary?
I have fretted over this for years. Back in the late 1970's I build 15 silver brazed Reynolds 531 frames and forks. I didn't drill vent holes in the seat stays of fork blades in any of them. The main reason was conern that water from wet roads could get inside and cause rust.
Is there a definite reason for vent holes other than making it easier to braze?
Vent holes let expanding air out and it also lets water in/out during the de-fluxing process - flux is corrosive and should be removed. I like to have vent holes on both ends of the stays so water can completely fill the inside of the tube. Some builders come back and close up the vents after cleaning - do a quick braze where a nail is inserted in the vent hole.