help .065 stainless tube welds

[pescaloco]

hi all, i am having trouble in two ways - been practicing to make some railing for my boat.
so here is the problem 1 in .065 tube with miter or fish mouthed joints - if the the fishmouth has a perfect fit with zero gap I can usually weld with no burn through, but can not make the micro sized welds I allways see on rail tubing - using a #8 cup an 1/8 tungsten 10cf argon - no back gassing.

the other problem is to make a tight fitting joint with drill press & hole saw tube nothcher, the joint seems to spread out too far for a good fit then it burns through or I end up with a big profile bead to cover gap/burn through area.

any thoughts - feed back would be appreciated

[Pangea]

I'd use a 1/16" tungsten and purge gas. Fit up is critical on thin material; though I don't consider .065 all that thin. If you have a pulse on your machine, use it. I've never had the luxury of using pulse but I've watched it done and recomend it.

Good luck.

eta- turn your shield gas up to about 18-20 cfh.

[holeyroller]

If there are any gaps in the joint...you can use some small body hammers to close down the gaps, by tapping in the offending gap until it joins up...it is not hard to do on the thin stuff, you can use a blunted chisel to draw them together as well.

[pescaloco]

thanks, for the replies
will the gas purge help in the actuall welding or will it just make a stroner joint with out oxidizing the back side of the weld joint ??
getting those really small weld beads are elusive so far, but will try 1/16 tungsten.

the closing of the notch joint is exactly what I need to do - good tip, the fit up is defiently criticall.

thanks, mark