Not sure what you are trying to build but I would do a few test pieces. Lis2323 mentioned grinding to shiny metal and I would start with a 5P+. If that's not satisfactory talk to your local welding shop or supply store. They usually have some good suggestions.What is the best way to weld up Black Iron? Can brake or carb cleaner be used to get it clean enough to weld and what is the best rod for it. I weld on rare occasions just for home projects..
That or use the wire wheel on the bench grinder to get it shiny, otherwise whatever rod you are used to should be fine. Its called iron pipe, but the pipe is actually steel, not iron (fittings may be iron though).I would just grind the weld area (and a spot to attach your ground clamp) shiny.
I do the several HF grinders too. I liked the one that had the switch on top not the side but have been unable to find that one. I have arthritis in my hands and it just worked better. Anyhow the last time I bought a couple of the side style I took a quick look and just by removing the 4 screws I could rotate the body and put them back in. Now I have the switches where I like them. Some minor vent is wrong but it works.Brimfield has not responded on his projects and success with his black iron pipe which I am sure is just plain old mild steel pipe.
Obviously, Gary has done miles of steel pipe like I have. No special cleaning is required. Schedule 20 and larger wall thickness, you need to bevel and multi pass, that cleans up the ends and the root area with the grinder. Some pipe has a black coating on it for rust preventing in storage it just burns away and no problem. Rusty stuff, hit with a wire brush wheel on your grinder, if heavy, hand wire brush works OK on light rust. Old rusty stuff for non-critical work I just use 6011 o AC or + electrode on DC. 6011 is the go-to rod for rusty, dirty, painted stuff. Great field repair rod. I also use 6011 for galvanized pipe. DO NOT weld galvanized where you can breathe in the fumes. You will be sick for several. days with zinc oxide poisoning. Inside a building you need to have an air suction device close to where you are working. If you want a fire use you vacuum cleaner. Not a good idea unless it is clean. I try to do it outside when possible.
I got tired of changing wheels on the grinder so I bought 4 cheap HF 4" ones. One has 1/4" grinding wheel, one gas a cut-off wheel, one has a wire brush, and one has flap wheel. They hang on the back edge of my welding table where handy plugged in and ready to go. At $10 apiece the grinders are throwaways. Thinking about replacing with battery units to eliminate all the cords. Have one I keep a thin cut-off wheel on for quickies outside.
Ron
I do the several HF grinders too. I liked the one that had the switch on top not the side but have been unable to find that one. I have arthritis in my hands and it just worked better. Anyhow the last time I bought a couple of the side style I took a quick look and just by removing the 4 screws I could rotate the body and put them back in. Now I have the switches where I like them. Some minor vent is wrong but it works.
Like others here, I have multiple grinders with various attachments that allow me to grind, cut, sand and polish without changing wheels. I have an assortment of brands. In the 4.5" size, I have 2 HF Chicago Electric with paddle switches (I prefer paddle over the push button), 3 Dewalt (had 4 but one recently bit the dust), 1 Hercules 6" and 1 Hercules 7-9" with safety guards for each size. I also have one Earthquake 20 Volt battery powered one that I use when 110v power is not readily available. This may seem like overkill but you can never have too many grinders (or welding machines--I have 4 of those)
I've always had a liking for 7018: it welds through grease, rust, even its own slag. It's designed for welding dissimilar metals. It will weld spring steel to anything.What is the best way to weld up Black Iron? Can brake or carb cleaner be used to get it clean enough to weld and what is the best rod for it. I weld on rare occasions just for home projects..