Somewhere out there there is a web page with a picture of someone's pipe forge that incorporates the recuperative pre-heater concept (a la Sandia forge/furnace). But, alas, I lost all my bookmarks some time back and can't for the life of me remember who/where these pictures are. Anybody out there recall the site? Dave Brown Blacksmith/Tinsmith Green Bay, WI ABANA, UMBA, GoM, MODA, ARG