Yep, poor attitude can negate a whole lot of good training
Quote: "Is it worth cooking the whole assembly before the final machine work Ron? I have been told all sorts of stories of the need for stress relief."
Stress relieving of weldments is industry practice. but I can attest it is rarely done. Generally it's not necessary for simple parts, but for components with long moments and precision is required between perhaps dowell hole location in relation to another surface etc, then yes it is imperative. Just as Fred notes, internal stresses can fight one through the whole job right through to the finish machining, each layer of material that is removed alleviates some stress and invites further deformation. The machinist just keeps jumping back and forth between operations and arriving at a compromised result that will suffice, otherwise referred to as a "bad day"
As Fred noted, brittleness along the welds poses a definite need for stress relieving, however in most of our hobby designs we typically overbuild with safety margins as high as 10 times the service requirement, and why we get around dealing with internal stress relief to any extent where component strength is the concern.
-Ron
