Verticle up or verticle down with GMAW?

[ZACHV]

A buddy and I are doing a rather large project to a friends Jeep the weekend and we had to replace a portion of the frame. My question is one posed to me by Jim since he knows I can get some great info here.

He is a bulldozer mechanic for Cat and has always been told to weld verticle up, and can do it fine, but on one of the joints he showed me his verticle down and it was tremendous. Actually looked like one of Dans pics.

He asked me to post this question here for better knowledge: Why is verticle up recommended and is verticle down definitely a no-no?

Thanks.

[cope]

Only reason I can see is that you have better puddle control on up than down. Same with stick or O/A.

[Dan]

ZACHV

It is all going to come down to the potential weld penetration that can be achieved. Let me try to explain. Vertical down is going to produce shallower penetration then vertical up. Actually, as the material thickness increases vertical down can easily produce a lack of fusion. The problem with vertical down is the fact that you have to battle gravity so that the weld puddle doesn t get a head of you. What this amounts to is a very quick travel rate that allows very little heat input into the basemetal which doesn t allow the weld bead to burn in. Now on vertical up,because of gravity the weld puddle wants to sag in the opposite direction that your traveling so that you have no problem with the weld puddle getting ahead of you and because of this you can use a slower rate of travel so that enough heat will build up to allow the weld bead to burn in the basemetal. I hope this makes some sense

[Sberry]

Better is a realitive term in this case. A lot depends on joint design, fit up and material thickness. On thinner material where it will heat up and there is plenty of gap down can be fine. As Dan said, the material needs to heat well enouigh to fuse. A lt of structural is done uphill especially on heavier materials. On a frame splice on a Jeep if there was enough gap and you could do it either way. The web doesnt really take a lot of the stresses anyway, most of it is the flanges. If it is a butt splice we always grind a smooth finish when its done. I dont even want to see that its been welded it I can. This is especially true where flex is occuring as there are no humps from weld beads to start cracking along sides.

[Scott V]

I was kind of wondering something that is somewhat on the subject.How about out of position welding with pulse spray,up or down?It kind of seemed easier going down.I was just messing around for about five minutes trying it.Seems like pretty good fusion,and penetration using vertical down.It was easier for me that way,but I really didn't try very much pulse up.I was using some small .030 wire on some .250 metal.I just wanted to see how much you can do without changing wire sizes or type.This was steel only,because Aluminum needs to go vertical up for the cleaning action.

[Guest]

Vertical is not a definite no-no. We had a project here where we had to certify our welds in vertical downhand welding. The main difference between the two is uphill gives you more reinforcement than does downhill. You gain strength in uphill. Another project where I used downhill exclusively was building chemical tanks 8' x 6' x 15' out of 316L 11 gauge stainless. If the puddle gets ahead of you, ya just let the excess fall on our shoes and keep going!

[Dan]

ZACHV

In my original statement, I was only thinking about thicker material. On thinner material vertical down is the way to travel, because going up will put to much heat into the basemetal . Which if the material is to thin will just cause you to blow holes in it.

For most mild steel or SS welding that home hobbiest weldors do 1/8" and thinner can be welded down hill, without any weld metal to basemetal fusion issues.

[ZACHV]

Gentlemen, thank you for your responses, I have printed this thread and will let him read it.

I appreciate it.

[ZACHV]

BTW, this is what we did this weekend:

Took this:


and made it look like this:


We made the wheelbase 5" longer for stability by stretching the frame in the front and rear and swapped to betting leaf springs and put them on top of the axles to gain about 5" of lift to go from 32" tires in the first pic to 38" tires in the second. It was a lot of work, but within 48 hours we have it back on tires. I would say we have about 20 hours in it so far.

[morpheus]

Originally posted by Dan
ZACHV

In my original statement, I was only thinking about thicker material. On thinner material vertical down is the way to travel, because going up will put to much heat into the basemetal . Which if the material is to thin will just cause you to blow holes in it.

For most mild steel or SS welding that home hobbiest weldors do 1/8" and thinner can be welded down hill, without any weld metal to basemetal fusion issues.

You state 1/8" as the minimum for ok downhill. what about 3/16" or 1/4" ... that's what I mainly work with.

- jack

[Dan]

Originally posted by morpheus


You state 1/8" as the minimum for ok downhill. what about 3/16" or 1/4" ... that's what I mainly work with.

- jack

Jack

Vertical up on these thicknesses is going to make a much stronger weld joint then vertical down. So, as much as possible on 3/16 and 1/4" I would weld vertical up. On these thicknesses (especially on fillets) vertical up burns in real nice to the root of the joint, where as with vertical down if your not highly skilled you can loose the race with the weld puddle, then lack of fusion to the root starts occuring. And also, if you skill level is really poor this lack of fusion can be worse then just not burning into the root. Now if you are welding a open root butt joint on these material thickness you might need to go vertical down on the root.

To be honest with you though I don t do any welding that requires certification. So, I m sure Rocky D or others who do such can state times were they were require to go down hill on this thickness. Most of my welding is either on farm machinery for my dad, or at work where Im welding on something that another persons safety depends upon the quality of my welds so I try to make the structures that I build or repair as strong as possible. So, for me this means as longs as I have access to be able to weld the joint vertical up, Im going to weld it vertical up.

[Sberry]

I agree with Dan but so much is dependent on the skill of the operator and the requirements and location of the joint design. Some welds need to be full strength and some it doesnt matter. On a frame splice like you may have often you can weld the inside where its hard to get at first, then back grind the outside and weld again. For butt splices it should be full pen and smooth finish. For te web it is not quite so critical, but the flanges really take the stress. When I splice one you cant even tell where when its finishhed.

[Sberry]

I like welding vert, in fact woul rather do it than flat. I understand Dans philosophy but I build structures as strong as necessary. There is no point in puting a 40 thousand pound hitch on a Toyota.

[Dan]

Originally posted by Sberry27
I like welding vert, in fact woul rather do it than flat. I understand Dans philosophy but I build structures as strong as necessary. There is no point in puting a 40 thousand pound hitch on a Toyota.

I agree with you 100%. For example if I had to weld (vertical) a bracket for an electrical disconnect onto a peice of equipment and both the bracket and piece of equipment that it is being attach to are made from the material thicknesses that Jack was asking about I would have no problem welding vertical down. Poor example but you get the idea.

[morpheus]

thanks for the info guys. I'm very confident in my vertical down and don't "lose the gravity race" like Dan said. but I don't want my welds to fail. I guess i'll practice my vertical up some more.

Dan, was it you that posted that pic of the vert up pattern ?

- jack