welding on underneath side

[Hugh Warren]

What is the trick to welding to pieces of metal together from underneath them? I am attempting to weld a piece of rebar to an iron post and I do
fine on the top side but cannot get the underside. The puddle just drips down
and cannot get any fusion?
Thanks

[JimDon]

You will do a lot better with 7018 or the 7018ac, if you have just a buzzbox ac only machine. Please go back into the archives and check some threads on doing overhead. The 7018 is rated for overhead because it is a slower burning stick (I'm assuming you're stick welding this, if not there will be threads on MIgging overhead too.) and you can keep the weld puddle from falling down. You can also push the puddle back up. Overhead keeps a lot of us frustrated and just because we can spout the rhetoric on how it should be done does not mean we can do it expertly. It takes practice, practice, practice. Work on a couple pieces of scrap before you try your good stock. Also, depending on your position under the weldment, you may want to put a pair of earplugs in while you're under the hood. Molten metal dripping into your ear canal is not a good thing to have happen. Good Luck and let us know how you do.
Jim Don

[Sberry]

You are probably going to need someone to show you. It will differ slightly with electrode type but can be done as well as it can in the flat position. Not sure how to explain it here but overhead is actually my favorite if I have one.

[TOMWELDS2]

Welding to 'iron'? 7018? Are you sure it's cast iron? If it is, 7018 isnt a good choice...my .02

[thingy]

You answered your own question,[not trying to be a smartass],its easier to weld flat than overhead,gravity thing,plus a few others,many out there think they are pretty good,than they try overhead or something,they soon learn they wern't as good as they thought they was,when you are good,your over heads should look like your flats or verticals,,just 98 percent technique,rest ain't much,,,practice before you try it for real,than you'll know,thingy

[OldSparks]

What is the trick to welding to pieces of metal together from underneath them? I am attempting to weld a piece of rebar to an iron post and I do
fine on the top side but cannot get the underside. The puddle just drips down
and cannot get any fusion?
Thanks


You've probably finished your project by now but I'll throw this in. Don't get too discouraged with overhead...the weld you were trying would be an extremely tough one to start out on. The differences in the mass of the rebar and the the wall thickness and the shape of the groove weld create a number of problems.
....the two pieces have to both be at a minimum temperature for your filler to tie the two pieces together. You are probably getting one side too hot and thus the metal runs down. If using 7018 you can expect some slag to run down before the bar heats up enough to except filler. It takes patience and a gentle hand to know which side needs the heat and there is potential porosity problems if you try to make your tie too early.
....to make to weld easier you might want to run a grinder along the bottom after welding the top. This changes the weld to a simpler fillet weld
....another option would be to run your first pass on the bottom directly to the post without trying to tie in to the rebar. This leaves you a shallower groove to tie together.
....my own opinion is that this is where 6010/6011 would be easier. With these rods you can strike your arc and back off and long arc for a few seconds to preheat both sides and then muscle your way in to make the start. A lot more sparks but easier to control the slag and form a puddle..