stainless needle purging ... ?

admin

hiI was wondering if some people could help school me on a proper needle purge technique...so far I've heard that parchment paper dams are used and when doing the root you leave a little window to keep the needle in to keep purging during hot pass and cap.. then pull the needle and quickly fill root, hot pass and cap while argon is still in the jointthat's just what I've heard but if anyone knows any other information, would be greatly appreciated... ty in advance
Reply:You pretty well summed it up.  Smaller tubes, you can ball up rice paper as dams.  They'll dissolve in water.  Is usually safe to pull the pin and complete root after hot pass.
Reply:do you think you would put a vent hole in the rice paper dam?I was thinking with no vent hole, there would be more argon contained in the joint during rooting/hotpass up until only the needle window is left to weld... once the needle is pulled out, the argon would sit in between the dams instead of leaking out the vent hole while finishing root and hot passassuming the rice paper dam is sealed.. just wondering what anyone else thought of that
Reply:Never bothered with vent hole.  Fill insides at a higher suitable pressure and then turn down to trickle to maintain purity.  Make sure needle angle is not going to affect  the root