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tack weld stainless steel quick like this, read on...
Stainless sheet metal fabrication projects can be tricky. Not only do you need to know how to weld stainless, but you need to learn how to tack the stuff too.
The best way I have found to tack weld stainless steel sheet metal is:
• Make sure the fitup is tight with absolutely no gap
• Prop your tig cup right on the joint with the sharp tungsten electrode tip less than 1/16” from the joint
• Set the tig welder to hit it hot and fast when you press the button or foot pedal
• Hit the foot pedal or torch switch and let off as quick as humanly possible
This Kemppi Mastertig MLS 3000 ACDC tig welding machine has a setting for high speed tacking which basically gives you an arc for a few microseconds…quicker than you can do it manually...
It makes the stainless fuse together fast …before it has a chance to heat up and warp and try to open a gap.
This is a very useful feature. It uses the same concept as a pulse YAG laser welder….which is to Hit it hot and fast with concentrated heat and the metal will melt and solidify so quickly that heat input and all the negative things that go with it will be minimized.
If you were a business owner, watching your employee tack a piece together fast like this would make you happy...and glad to buy the welder an autodarkening helmet. (which by the way, is a very important part of this equation)
. ..and if you are in business for yourself , you can see the competitive edge you would get by being able to make about 20 tacks in less than a minute without ever lifting your welding helmet.
Even old school tig welding machines have switches to allow you to go from zero to 100 amps all at once, but you have to be quick with the foot pedal.
For example on a Miller syncrowave 250, the remote amperage switch would be set to “panel” instead of “remote” so that when the pedal or torch switch was pressed, you would have the full amperage set on the dial…which for tacking stainless quickly should be about 1 to 1 and 1/2 amps per thousandths of thickness of the metal being welded….
So if you are tack welding .063” stainless, the machine should be set to around 65-95 amps.
95 amps would be too hot for welding .063” stainless but for quick micro- burst tack welds, it provides the arc force needed to force the puddles from 2 separate pieced together to make a quick tack.
But a caution here: the fit has to be tight or you will just melt the edges away.
" Hit it hot and quick..."