If you download the DFM/CE check lists Phil talks about, you will see it is possible to design, fabricate, and assemble asymetrical MLB constructions without violating and bow and twist requirements specified in the master drawing - also contained in the check lists. However, there are many factors involved in any success regarding these requirements. Materials are one. Constructions are another. Lamination process management, from start to finish, is another, etc. I currently am looking at page 73, Section 9.7 of my check lists and see a MLB construction completely out of wack but it worked because of concurrent engineering. The board used to be a potatoe chip. It is now being produced in volume as flat as a pancake. There is so much more and I do wish you well, MoonMan --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------