Another Welding Question......

As is typical for my ability, which I think has become proficient in most positions with this electrode with varying heat settings, depending on what I am doing. The joinery of materials seems to be going well, plenty of penetration, hardly if any porosity, and the profiles look well, they are uniform and convex. I am confident that all the work is done correctly and is strong.

While adding a pass to a previous welded joint,( not by me ) to make it look good, and it's only 2 1/2" long, but on the bottom flange, (the under side as if looking from the ground) of a C-shaped channel, I burned through somehow while trying to weld over head. This is probably due to the arc distance and not moving quick enough with the heat setting at 130 amps DC, 1/8" 7018 electrode. Situated underneath the member looking up, welding upside down/overhead has always been difficult, but I've made progress, had some other short joints to make a pass or 2, where the other side was already welded substantially, just wanted to make the inside look nice, and I did ok, but you can't win them all, arm was tired, did not move fast enough and I made a hole, which got to be about the size of a quarter while attempting to plug weld it.

Directly beyond the hole is a 1/4" mild steel plate, so it's only through the 1/4" C-shaped member, I turned up the heat and went up to the larger electrode, as it seemed to deposit some material on this plate, whereas before while even trying to build up the edge of the hole, let cool, repeat, most of the material would drip out. I have closed up holes like this on occasion in other positions where I've burned through a thin spot or had the heat up too much, but upside down sure is tough. Trying to make a pass and have some material deposit seems difficult to do in this particular scenario, too hot it drips out, too cold it electrode sticks, in between some material deposits, but can be negated quickly with one wrong move, and the profiles can become lumpy, as opposed to welding flat, which is so much easier.

I'm wondering if there is an electrode that is better suited to plug welding upside down, and or there is a more defined method if anyone has a suggestion.

I was thinking of changing polarity to AC and using some 1/8" 6013, like I use on my AC 225 lincoln, for this one area, thinking it's a better all position electrode, and the joint would be fine as long as it's filled. I'm using a Miller NT-251 trailblazer.

One other consideration, while attemping to plug the hole, the plate beyond which is heavily welded laying flat on the upper side of the bottom flange, with 1/2" welds. I did turn the mild steel plate orange across the joint area before I decided to not waste any more electrodes, I try to avoid over penetrating and or heating any steel like this when possible and am wondering if the mild steel plate would be effected, by hardening, making it crystalline, brittle etc.

The previous and other threads have always been interesting and helpful. It's a handy skill to have, do apprectiate any and all suggestions thanks again !

Interesting situation. I'm impressed at the quality of the advice you've already received. I've got no experience filling burn-throughs or bridging gaps in the overhead position so what's worked for me might not apply here. I use 3/32" rod, particularly 6013 but sometimes 7018 for buildup when the problem just keeps getting worse. 6013 isn't a good out of position rod though. 6010 and 6011 burn with such violent arcs that it's hard to believe that they won't make a burn-through worse, but the fast freeze quality really works, as TimV noted. Plugging the hole with a piece of scrap, as jdemaris suggested, can really change the feeling of the problem. Instead of a frustrating error repair, it becomes a normal welding situation. Plus, the additional mass widens that fine line on getting the right amount of heat.

The one suggestion that hasn't already been offered is to knock together a mockup of the specific part you are trying to fix and do your experimenting on that. Nobody ever bothers to do that, whether they think of it or not, because they usually expect to get the problem taken care of in the next ten or fifteen minutes and it would take longer than that to find some scrap and copy the problem area. But if you're having enough trouble that you can leave it while you go to the store for different rod, and/or the appearance or structural integrity of the finished weld is important, then experimenting on something other than your actual piece of equipment might be worth the added effort. You probably already know this, but if you decide to make a model of the problem to experiment on, a fast way to put a hole in plate is to crank up the amps and push a 6010 or 6011 rod right through. It's a quick and dirty way to cut metal, but in a situation where you're trying to simulate a burn-through it seems perfect.

Good luck and let us know what finally works, Stan

Aside from my question, I have to applaude the helpfulness of the people here, it's a great thing, when you are not proficient at something or encounter a problem, having a resource of a forum like we have here, is a great asset because each of us can probably offer advice about things we know well, covering the gambit of most problems encountered when doing mechanical repairs and so many other things. It's highly appreciated.

I call it a mock up, we used to do these on construction sites quite often, mimicking condition or a portion of the work, many times called for by contract, to be done specifically at a testing facilty. I did a mock up with a company,( was their product ) Benson Global from out your way, Portland WA., in Ontario, California in '02, at Construction Testing Lab West, if I recall the facility correctly. This was for a big project in NYC, requiring that performance testing be done on the metal and glass panels we were contracted to install on a high rise building. Benson uses the facility in CA exclusively, so we spent a few weeks out there.

I cannot tell you how helpful it was to take the lead Ironworker Foreman to the job and do the work on a small scale, that and visting a jobsite in progress, which was the new MGM headquarters in century city, 40-50 story job (I forget,have to look at the photos again) using a similar product from the same company. We visited the site twice and took some detailed notes, what we learned was very valuable on our own site, our foreman got some great up front knowledge, helped him immensely when our project commenced. Firm believer in doing mock-ups.

I do take scrap steel and dial in prior to doing any work, changing heat, electrodes and position, so I do not screw up the actual work, electrodes are not cheap, but it's worth burning a stick or 2 to get that initial feeling for the work, especially being a non-expert.

I did go to the supply house yesterday and stocked up on material I use the most of, 7018. The smallest 6010-6011 packages were a little too big, what I did not use may not be needed for anything else, so I'll take a piece of mild steel scrap and wedge it in there, I'll bet I can make that work with the 7018, I was close but no cigar before, then get a good pass over it to button it up, it's good that the plate above heavily reinforces the connection, so this is more for aesthetics, I've really fussed on this truck frame so far. It's come out nice though, especially the 10" section of the upper flange near this joint, I took the same thickness angle, cut one leg off to match the section cut out, it was a tight and clean fit,( fit a piece of scrap first, another mock-up LOL ) inside radius matched perfectly, it welded up nicely, and it matches well after I made enough passes on the outside corner of the member which I then lightly shaped with the grinder, being careful not to over do it. I may get to work on today, but will post my results of this burn though repair. I've got some photos, just time consuming to re-size, then post at the remote site and match the link here, might rain later, I may post a few.

Do appreciate everyones help, thanks again !

I know machines vary, so you adjust, I'm thankful most of the joints I'm working on are just hard to reach at worst, but not over head or vertical. I thought 120 worked well with this NT 251, and 1/8" especially after the 1st pass, does not seem to overheat the base surrouding metal if you keep moving, and the weld profiles look good, hotter, they can over penetrate it seems, I agree, no expert here but I think I'm doing well so far.

I've done some vertical work to build up a thin area on the web, depending on the penetration needed, I adjusted the heat down, and moved quickly, but still deposited material uniformly in thin layers, which I could not do so well before, sure takes time and burning of some rods to get better at it. I was careful as to not over penetrate and overheat, was a small area, but still the web, really had no other choice, it's near a large vertical joint, that has a large weld, bottom flange was plated off spanning the joint and also gets 3/8" angle bolted connection spanning the joint for the dump body mount, so that ought to be quite strong.

Talk about moisture, the last several weeks have been a literal washout, I've learned about those characteristics of 7018, I have not had much trouble using those electrodes, I keep them in the house and put them under a work lamp before I use them, but even on the restrike, seems you have to knock off the slag on the end of the electrode to get an arc started again, many people do have trouble with 7018 from what I hear, it does make a strong joint. I can imagine where the low hydrogen welds are concerened they handle the electrodes by the book, I know an inspector was breaking chops about pre-heating, using an electrode oven and some other AWS criteria on some structural connections for a curtainwall system we were installing in Queens NY a few years ago. He was right, I fired my erector over these technical issues as he was opening a huge can of worms on the claim and re doing unacceptable work end of things potentially costig the company a lot of money, this was a state job, it was a courthouse. We replaced him with our crews of in house ironworkers immediately. It may have seemed petty, but the inspector was really pleased with a few changes and a pleasure to work with after, every joint passed and through the experience we learned quite a bit for our own benefit.

This is a truck frame actually, and this joint is probably non-critical, the rest is done properly, but still part of the member so I need to close it up and make it look good, the rest of the repairs have been time consuming to do correctly, but worth the extra time, they're strong and look good aesthetically, I don't think I'll have any problems here, especially with the d.o.t. guys i hope, registered agricultural as well. It's an old truck, 1964 F-600 the steel is not hardened. I've got quite a few pictures to document the work, but this hole sure looks like a rank amateur did it LOL ! I know I'll get it done, just had to ask for some advice, was spinning my wheels a bit.