I have found that running 7018AC rods on DC gives me better restarts. 7018 requires heat as has just been voiced, and shiny weld areas. Even fresh A-36 HR steel can be perverse if the mill scale is left in the weld zone. You'll know when you're running hot enough because the weld slag removes itself.
Just to add a little more to this thread- A 6011 or 6010 root pass under 7018 will help by getting the joint cleaned. 7018 is finicky about where it will stick but 601x will fuse bubblegum to bondo.
Also if you are welding to spec, do not assume that you can use 7018AC where 7018 is required. Some 7018 rods are labeled with H2 H4 or H8, those relate to the hydrogen that is outgassed (2,4,or 8PPM IIRC). Excess hydrogen can cause hydrogen embrittlement and lead to weld failure.
Other than beam size (very important, considering overhead load) salient points in this thread:
-hot welds (penetration, boils slag up & out)
-preparation/ fit-up (clean, clean- tight fits) takes time but safer than sloppy
- interference (don't build engineering nightmare which tempts you to cheat - the trolley)
rod size- I'd rather run 1/8" with more passes because you can see your flaws
position- flat, whenever possible. Its a PITA to move/ roll the work but weld quality is WAY better. Horizontal, vertical, & overhead are not the place to experiment.
AWS rod number definition- not everyone knows what the numbers means- 60xx does NOT mean 60,000 tensile strength with a pass on each side of a square inch pad. Does anyone know of a well written definition of all four numbers? (strength, positon, polarity.)
That Lincoln "5P" was/is pure BS- it only promotes brand recognition- doesn't give the user any tech info.
I'm no machinist- a fair fabricator- preparation & some knowledge of the process are my only reasons for success. Thats why I'm here- to learn.
thanx to everyone, mike
Some rod number info is here: Rod_Numbers_Decoded
very interesting,learned lots in only a few minutes reading.no hijack intended
my need to do overhead welding on certain items leaves a lot to be desired.weld,grind,weld grind,you get the picture.
i prefer to arc instead of mig,even if the mig process is far easier.
i am learning,forcing myself to make flux smoke.when my boss blasted me for the gas bottle being almost empty,i decided to practice my arc welding.he emptied it on the weekend,he can fill it.
practice makes better.
thanks for the read,Gents....
If you can weld flat, you should be able to weld overhead. I find it easier than horizontal or vertical. Turn your amps down a bit from your flat setting. Because of gravity, you don't want a big weld puddle as it will sag. Oh & make sure you're all leathered up.
A suggestion I would make is find some 3/32" 7018 rods and practice with about 70 - 80 amps. Flat first then, vertical from the bottom. It is easier to control the heat setting. If melted steel drips out, it is too hot.
Rod will stick on start. I have been doing that for a lot of years and still cuss getting started.
Finally. A subject on which I can contribute some know-how!
Dave: I second (or third?) what WB and the others said. 6010 and then 7018.
6010 is the pit bull of the stick welding world. It will dig down with a vengeance and get under paint, rust, oil and other nasties. However, that is not to say you shouldn't clean everything first. You should. It is easy to run it too hot and burn through your work however. Do not expect a pretty weld. But if you run it as hot as possible without getting undercut or burn-thru you will have a weld you can rely on.
As to the 7018 it is my favorite. Here's a trick I've learned. If you run it on the hot side at just the right amperage setting the slag will PEEL ITSELF OFF! Underneath you will have a weld of shimmering beauty.
The great thing about 7018 is that if you hold the rod at the proper angle (10 - 15 deg.) you can TOUCH the metal with the rod. Then, after it's burning good, PUSH the rod DOWN and in the direction of travel.
Imagine this. You're holding a stick of uncooked spaghetti over a cooking pot containing 1/8" of boiling hot water. You want to lay the spaghetti in the bottom of the pan.
Insert it at the right (10-15 deg.) angle. As the end of the spaghetti gets limp push DOWN while simultaneously twisting your wrist slightly in the direction of travel.
Once you get the hang of it every stringer bead you lay down will be perfect. To my understanding and based on my fairly extensive (but strictly hobbyist!) experience, 7018 is not a "fancy footwork" rod. But by adjusting the amount of "push" and the amount of "twisting your wrist" you can lay down a beautiful bead that is either thin or wide.
If you stop a bead 7018 is hard to re-light. It's best to start with a fresh rod. Then when you have a bunch of partially burned ones you can scrape the flux dimple down to bare rod and light 'em again. For code welding 7018 has to be kept in a rod oven. For diy work it doesn't matter. But just so you know, after it's been out in the air for a while it is unacceptable for such work. This is not to say it's not usable however.
7018 and 7014 are similar in the aspect that they're the best rod to get a beautiful bead. But as I recall, 7014 is not all position. I don't remember how to read the numbers but I may be mistaken about that. If so, no doubt a pro will pipe up and slap me.