Welcome to our little spot on the net. Back when I built smokers using an arc welder, I used 7018 for everything. It's stronger than the 60 stuff and produces a great finished bead.
I agree with CRS on the 7018 rods. That is about all I ever use, especially if welding on pipe that might be magnetized. It does make a strong, pretty weld and the slag cleans up easy. I never keep my rods in an oven, just keep them dry and don't keep around to long. I am not familiar with your welder and don't know if it is AC or DC. If it is AC get the 7018AC rod. They burn good on either AC or DC. If I was doing it I would just weld up the outside good. I think inside and outside would be overkill. Good luck on the build. jm2cw
These guys all suggested I use 7018 DC on the build I'd just completed. It all started with 7014 and 6013. The 7018 did make a nice smooth weld and a big difference from the 6013. I have very poor looking welds whenever I use 6011. Just can't seem to find a happy amp setting for it
Make no mistake, there ain't no powder in this Puff ! And... I'm not really a crazy person but I play one in real life
I burned mostly 6011 rods on my build. 7018 on the trailer frame. You'll be just fine either way, but use the one you're most comfortable with. And welding both sides of your joint is overkill, the outside alone will be fine
I would use the 1/8" 7018AC rods with the AC welder at 105 or 120 amps welding the 1/4" metal. The AC welder will run the 7018AC rod with no problem and it is very easy to strike an arc. You can run the DC rod on a AC machine but it is hard to strike an arc. You have to knock the slag of the end of the rod to strike the arc. I have burned a lot of them.
Not to hijack the thread or anything...But I have troubles getting the arc going steady with the 7018. I bang the outer covering of the rod (I'm sure there's a name for this) off so the electrode is there but I get a spark or the rod sticks. Even if I do get a small arc going, it's hard to keep it until a few full seconds after I have been going.
I've tried higher amps but then I just burn through.
Try 3/32" rod?
AC or DC welder? It sounds to me like you are trying to burn a 7018 DC rod on an AC welder from the sticking rod trouble. To strike an arc it seems to me like you have to hit the rod on the metal a little harder and immediately raise it just enough to keep the arc going on the straight 7018 rod. The 7018AC rod is made for AC welders and is a lot easier to strike and maintain the arc. I burn both kinds on my tombstone Lincoln AC 225 that I have converted to weld either AC or DC.