I haven't seen it mentioned so I'm beginning to think it may be frowned upon but a very quick way of melting the scrap is to use the "Universal Key" (oxy-acetylene rig) to speed the heating of the scrap. I'm aware of the fume danger and I wear the necessary safety items. Playing the cutting tip flame over the surface of the scrap while heating it over a burner greatly reduces the time required to bring things to a liquid state. No problems so far, but I make very sure to have the wind carrying the smoke/fume away from me.