My question is about welding up pieces together for my next JYF. I've made one before and I'm looking to improve on the manufacture of the next one. I'm using a brake drum set in a steel plate and the pipe is 2" schedule 40. Last time I just kept welding until it was just a massive bead. I use a Lincoln Mig sp135 with a Lincoln multipurpose .035" flux core. I don't use shielding gas.

Would there be different type of wire to use to get the pipe to weld to the brake drum better?

maybe build a plate to weld to the pipe and then bolt or weld to drum?

I'm with jimmy. The drum I have to use has a hub hole about 6" in diameter. I planned to make a plate to cover that hole with a hole the size of the tuyere, and the pipe welded to it. Then just drill for the bolt pattern and bolt over the hole.

The drum I use has a hole just around the same size of the pipe but I could just use the bolt holes to connect the plate to. Sounds like a plan, I had previously just welded pieces of rebar into the bolt holes to fill.

I chose to bolt my brakedrum forge together, as the welds will eventually crack from differential in heat in different areas. I have been using mine for 5 years with the same drum and pipe.

One of the easiest ways is to cut a hole in the plate to catch the outside lip of the brake drum. No welding. Rotors have a flat edge so cut out for the hub, again no welding. I would weld the air pipe to the drum.

BP0518 Making a Forge Pot

Yep my original JYF drum sits in a hole and I've used tabs to fit in the rotor gap to hold it down (I store it on it's side). And I originally welded the pipe to the drum, the first time I did a small bead and I guess I didn't get much penetration. It eventually cracked and fell off. After that I put on a bigger bead and then some more. The pipe is probably closer to 3 inches instead of 2. Instead of welding in my tuyere I made an insert to slip inside the pipe.
What I have works well I'm just starting to make another one that's a little more compact, the grating for the tongs and hammers will swing up into position and my travel anvil will have a shelf underneath to bolt it down to while I'm on the road. I want to make sure I have the joint 'tween the pipe and drum done well because welding is a bit of a weak point for me at the moment. (practice, practice, practice).

What you could also use is a metal floor flange bolted or welded to the inside of the brake drum. Mine had a 2" threaded hole on the inside where I just screwed on a threaded pipe nipple. You can get them with different ID hole sizes, depending on what size pipe you are connecting.
Brake Drum Fire Pot - Blacksmith Photo Gallery