As Jim said use the bigger peace to chuck the heat into and wet the edges of the smaller peace. Also I believe your taking on an inside corner joint around that small pipe so you will be needing a very focused arc to get your pool right where you want it so make sure you have a nice high frequency. 100-120hz should be pretty ideal.Holy crap welding small diameter (15mm) pipe end-on onto plate is hard
Just need to work on my consistency now.