I have a small shop, several weeks ago I was doing some tack welding with my mig. Yes, I know you are supposed to be in a well vented area but I had the A/C on, it was 104* outside. After a couple hours I noticed there were some fumes. I opened the big shop doors and sweated the last bit out. This past weekend I wanted to do a little more welding but the hurricane left 100% humidity and I didn't want my freshly sandblasted doors to start rusting. I was going to open a window and blow the exhaust out but that still would have brought a lot of humidity back in. Then I came upon this idea, and it worked. I duct taped the vacuum head to a large welding magnet and mounted it about 4" to 5" above the area I was spot welding. The exhaust end of the shop vac I stuck through a cardboard filler in the window. The smoke was sucked into the vac and blown outside. This was light welding and not continous but it let me tack pieces together without changing the air in the shop every 5 minutes.