Vertical MIG welding: uphill v. downhill

Uphill welding requires that you either set your machine perfectly and run a bead straight up with no washing back and forth (or maybe just a little), or you wash back and forth as a way to have a wide, slightly crowned bead. The wash helps you control the sag if done right. You will have more distortion on lighter weight materials though. Sometimes whipping across the middle and holding at the sides briefly before whipping across the middle again is the way to go. It's all about controlling the puddle. If it is sagging in the middle, go across the middle a little more quickly. If it is undercutting as seen in the one picture, stay at the edge just a little longer so the wire can deposit a little more weld....maybe crank up the wire speed a little. You can make a 1" wide bead if you want to. Make sure your cover lens is new so you can see what you are doing. Practice! An inside corner weld is actually easier because you can use the valley to hold the weld puddle from drooping. You can move the weld puddle in 3 dimensions by going into the corner, pulling back to one side, going back into the corner and pulling back to the other side. Downhand is easy and good enough for a lot of stuff, but if there is any doubt about strength weld uphand.

John www.ghiaspecialties.com

 

When I was doing some vertical up stick training, the CWI explained it to me like this:

Say you're down south in a pick-up truck with a couple of buddies, and you're passing a bottle of whiskey back and forth. Guy in the passenger seat gets a swig, then the guy in the middle, then the driver, back to the guy in the middle, back to the passenger seat, and so forth....who gets the drunkest?

So you wanna pass over the middle quickly

 

Hey John, met your brother and worked with him at Seattle shipworks this season, poor guy, under valued.... anyway yeah welding, lots of practice, this years practice for me was stainless welding with rod on ships factory, lightning fast with better results than tig and a prettier pattern

 

Yeah, my brother has been slowed down a lot by lead poisioning from a job he did a while back. Wish he would get out of that shipyard shit. He's had a good long run at it. I got out after a few years.

John www.ghiaspecialties.com

 

Hi guys! Thought I'd chime in here, for most automotive work you're only talking 1/8"-3/16" material. As long as your metal is ground clean to start with, either method, up or down hill will work.
However, for appearence and penetration on automotive weight material I use the 'Hot Stitch' method and vertical up. These are intermitant pulses of the trigger creating well blended interlocking spots of weld. Properly timed (we're talking fractions of a second here) the pauses between blips are just enough time for the puddle to freeze before triggering again.
It goes like this, with the gun held at about 45 degrees to the seam, (pointed up) trigger the weld. Hold steady and wait for the 'blip' to go round, let go the trigger before the 'blip' sags too much. Immediately aim at the leading edge of that first puddle and trigger again, let it go round. This second 'blip' will hang better as it is supported by the preceeding 'blip'. Again, let go the trigger before the 'blip' sags. and continue!
If the weld you are creating looks too fat, cut back the wire or raise the voltage just a bit at a time until you get the right balance.
Using this method, a skilled weldor can weld in any position, around tube joints as needed.
No, it's not as easy as it sounds but it is well worth the effort to perfect this specialized type of welding for light industrial work.

Dan Stevens
dba, Steelsmith

 

In the pipe welding industry there is only 1 downhill test. In true testing situations if it has been deemed that you downhilled anything past 10-2 oclock you will fail your test. The down hill test is for 6010 pipeliners, providing a good fit up up hill is as quick or quicker than down and the penetration can be controlled better.

 

That's the funny thing about welding there's many ways to skin a cat. Unless there is a specified weld technique for an application, it is up to the shop you are working for as to what is acceptable. That is why there are so many differing thoughts on what constitutes a good weld.
Just remember there are many different welding techniques. They were usually developed for a specific application and then adapted to other uses. In the old car business your main concern should be strength/safety.

Weld-on!
Dan Stevens
dba, Steelsmith

 

Lots of good info here. My .02 worth joint design and fittment are as important if not more than the welding direction, like in this case the weld aroud the tube would fail before the backing plate would tear away from the frame. I find having a gap slightly less than the thickness of the the metal works well bolth for appearance and weld strength usualy weld down hill on up to 3/16

 

For thin stuff, like 1/4"-3/16" and below, down is fine, so long as fitment and surface prep are all good, and that provided your machine is capable.

For all else, up can be stronger, technically, but most here are not welding over 1/4" very often. It is harder to do well, and takes a lot of practice.

 

A downhand fillet is going to have no root penetration and will often have voids at the root on anything thicker than 12g. You are relying on good looks to hold the welded pieces together. A butt weld will have little penetration and often coldcasts. Don't believe this? Make a few practice pieces and break them. They will always break in the weld or at the edge of it.
Strange that Caterpillar writes in their service manuals that Downhand welds are not acceptable for repairs if that is how they make them at the factory.

 

I like to weld my vertical joints up but while I'm inverted...so I guess thats down?

 

Well said. We call it "feathering" the trigger. Produces a nice looking weld & structurally sound.

 

yes!!

 

Needless to say you can learn something from these welds, flawless dude !

 

Kirk Hanning:

Thanks for all the info, everyone. I like those welds. I have done similar welds before, those intermittent trigger pulls, overlapping spots. Wasn't sure if it was technically correct or frowned upon, so it's good to hear that it's a good technique.

 

this is what i do, downhill side to side in a criss-cross like pattern..

 

We teach MIG welding on 3/16" plate and all vertical welds are run downhill. For good quality uphill MIG welds you need a fill wire other than the usual ER70-S2. A couple techniques to insure good downhill penetration... On open root welds (corner or butt joints), open the root gap slightly. Also try a "continuous stitch" motion on the downward travel. Without releasing the trigger, skip the wire downward to the leading edge of the puddle as soon as the bead size is sufficient. This allows the heat to get back into the root of the weld instead of building on the surface. With practice, this can produce very good looking welds with penetration equal to horizontal welds.

 

I came across a site once where a guy did some cross sections under a microscope to compare vertical welding. He did 3 techniques, vertical welding from top to bottom, a triangle technique from bottom to top, and an upside down V pattern(which is what people are calling the christmas tree pattern) from bottom to top.
Here is one of the pictures from his site:

From left to right the pictures go as follows; the welds themselves, vertical from top to bottom, triangle technique(bottom to top), and bottom to top christmas tree. Note: the picture of the welds themselves is indexed wrong to the microscopic cross section pictures. Follow his drawings on the plate itself for corresponding cross section.

Hard to argue with the results when you have a picture of a cross section under a microscope. However, with that said, most of my vertical MIG welds are done from top to bottom because I always felt that a good top to bottom weld is better than a shotty bottom to top weld.

 

I always heard "get down, don't fuck up" at the body shop I worked at back in the day. Meaning weld downwards. The dude was refering to welding sheetmetal. I do both depending how good I can see the area or access I have to the area.