Originally Posted by
Aaron Novak
Ok I see where you are coming from. My point is that you cant just hand an old factory drawing to a supplier and expect the same part as was made 60 years ago. All the information needed to make the part is NOT on the drawing, never has been and never will be. So thats why I am saying that not just anyone can take a drawing and have a part made, and expect it to be OK. Now of course its also dependent on the type of part, material, etc. A simple bushing from a copper based alloy should be straightforward. A ground bearing race for a roller type bearing, much more difficult to reverse engineer if it was even possible. A drawing for an exhaust valve may indicate the materials and dimensions, and if it were a multi piece valve may say "spin weld" or "flash weld" or just "weld". The details of the welding such as rpm, inertial loading and force ( if spun welded ) are not on the drawing usually. Since every supplier has its own ways of welding, if you just handed over the 60 year old drawing, they might make a part that while technicly meeting the drawing, might be unsatisfactory for use. Thats what I mean when I say that all the process engineering is missing, and so having someone experienced in the design field of the same components can be very helpful when it comes to reverse engineering it.