non-welder problem, aluminum tube joint issue

[cmd]

I have the 250ex just so everyone knows, so far so good on that end. However, I just got done welding the structural parts of 3 ramps for ATV's/lawmowers. The long side rails are 2X2" square alum tube. the cross bars are 1" square tube. So when I weld the cross bars in between the side rails I have 8 welds on each tube, the small cross tube is eventually sealed pretty much air tight when done (against the bigger tube). I can weld about 6 out of 8 joints then it gets very hard, nearly impossible, to weld the last one or two. I think the tube is heating up and the air inside is expanding and coming out the crack I am welding on. I turned up the argon to no avail. I can't really back purge the tube either. Does this sound like a reasonable problem and does anyone have any ideas on how to get around it. I may spoolgun the next time as its pretty time consuming with the tig, maybe that will help.
Chris

[Slick]

Drill a relief hole

[cmd]

Drill a relief hole

I considered this, would you go back and weld the hole shut or just let it open, are we talking 1/8" or 1/4" hole? the 1" tube is 12" long.
chris

[Gary]

CMD ,
you could just drill the hole in the 2x2 inside where the 1 x1 will be welded on then that would vent there.
It would just need to be .125 hole.
Gary