[cj737]

Is there a particular size of purge block that you've found handy? I figure a fairly small one could be just moved and clamped in position. A larger one might just waste gas.

How much gas do you think a 1"x1"x6" piece of tubing is going to "waste"? You're not wasting gas, you're protecting parts. Gas is cheap compared to oxidized stainless that rusts and fails.

I make blocks of all sizes when the need arises. There is no standard.

[Timmy_Tiggs]

So, I can make a small one and move it around.
What about gas flow? I'm guessing that you only need it to "breathe" on the back side of the weld you're forming.
Probably very little if you can more or less seal off the back of it.
We haven't done much stainless but we aren't busy right now and I'd like to be prepared instead of getting caught flat footed like the last time.

[cj737]

I run 5-10cfh. Again, the whole point is to protect the stainless.

[Timmy_Tiggs]

I could make one easily enough. There's plenty of aluminum angle and plate here. I'd just have to get an aluminum coupling to connect the gas fitting to. [edit] Actually after looking at a few examples, I should just get the proper tap size, drill and tap.