welding different thickness parts tig settings

by peter
(land of fire)

Hi, i´ve been following your videos on yt, learning all i can.

i´ve tried to make my homework but there is something i can´t find the right answer.

when TIG welding different thickness parts, say for example in a lap joint of a piece of 3/16 flat bar to a .14 ga (.080)square tube (mild steel or ss parts)( other would be a joint of small tube dia to solid rod like the one in the tig finger video), what would be the guideline for setup, amperage, tungsten dia, rod dia, and most important how wide the bead has to be.
in your video of welding 4140 parts you state that a 3/32 tungsten was used, can you tell me what amps and size rod would be for this job, also how do you judge that the weld size is right. other ex. is in the video of ss walking the cup vs tig finger you made a multi pass. other would be the hammer project you did on one of the videos.

the last question is regarding how to weld a ball bearing to mild steel and to high carbon steel

sorry for the basic questions.

thanks a lot for the videos, watching how it´s done has made a big difference to me.

regards

peter


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Peter,

a rule of thumb is that the size of the weld for 2 pieces of different thickness is determined by the thinner piece.

So for .080" thick tubing, welded to 1 inch thick solid stock would only need about .080" of weld size to have enough. but .080" would be a tiny weld. Having a weld size of 3/16" would be plenty and still not be oversize for most applications.

3/32 electrode is probably the most versatile because its good up to over 200 amps on DC with the right taper and can still weld very thin sheet if sharpened like a needle.

one way to determine amperage required for sheet up to .125" is one amp per one thousandths so .125" would need about 125 amps.

but that goes away quick because obviously you dont need 500 amps to weld .500" thick steel.

another rule of thumb is whatever amperage it takes to make a puddle the size you want within about 3 seconds.

you can try this on some thick but clean scrap metal.

for steels, once you get above about 1/4" the amps needed dont change a lot because you are doing multiple passes anyway.

I guess you can tell by now there is no hard and fast way to know amperage and electrode size needed but I hope I gave some help here.

thx for posting.

jody