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tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 7:26 am
by mopeep
Hi all,
Newby here having trouble with tig t joint. Mild steel-16 gauge vertical welded to 1/8 inch base plate
Parameters:
Tig
70 amps
DC, no pulse
15 cfh argon
ck9f torch w/gas lens #9 cup
3/32 2% lanth sharpened to 3/16 cone
1/16 ER70 filler
When I hold a real tight arc of about 1/8 inch directed at the thicker 1/8 inch steel to get it hot enough to puddle for a fillet, the 16 gauge melts and blows through.

Any thoughts on what I am doing wrong?
mopeep
AHP 200 TIG

Re: tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 8:13 am
by MinnesotaDave
70 amps takes too long to puddle the 1/8" and the thin material heats up and melts a hole - in my opinion.

I would be around 125 amps, puddle the 1/8", sneak the puddle over and add rod just as the thin stuff gets "wet" to join them.
(All in about 1-2 seconds)

Make sure to add rod often enough and keep moving to keep the thin stuff from blowing a big hole - a small keyhole is fine though.

I've done this with about 1/16" square 4x4 tube joined to 3/16" plate - I was at about 180-185 amps for it and held full pedal - those joints went fast :)

(Had a bunch of them to do and wanted to motor out - lol)

After doing several, you see where to point the arc for starting the puddle without tinkering around - arc on, puddle starts on both, add rod and get after it :)

Re: tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 8:30 am
by mopeep
Thank you, will try hotter technique and sneak the puddle :) .
M

Re: tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 8:44 am
by Rick_H
Yeah Dave is right on, crank the amps up and 1/8" isn't tight for arc length.

Re: tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 1:40 pm
by motox
keep the arc tight enough so you have to move it out a bit
to ad filler.
craig

Re: tig t joint with different thickness steel

Posted: Wed Sep 09, 2015 7:37 pm
by mopeep
Great advice, I will give it a go this weekend. Gotta pay the bills until then.

Re: tig t joint with different thickness steel

Posted: Fri Sep 11, 2015 4:44 pm
by mopeep
Minnesota Dave and others,
Cranked the amps to 130 and worked the pedal. 'sneaked the puddle" over to the thin stuff, kept it motoring along, and things went great.

Thank you again.