Hello everyone, I know that many of you have the need to roll various types of materials into round shapes: narrow widths(rings), wide widths(pipe), essentially. Generally using the centerline diameter of a round shape and multiplying that number by PI will yield the circumference(which is also the length of the flat material required to make that particular diameter round object).

Some folks will figure this by using the ID of the part and adding one material thickness to come up with the centerline diameter, others will use the OD of the part and subtract one metal thickness to come up with the centerline diameter to use for figuring flat layout length. Either way comes up with the same answer.

In addition to this, it is often a good idea to allow for a bit of additional material on each end of the piece to provide for pre-forming/rolling the ends prior to fully rolling/forming the part. This is required when the rolls being used are not of the type that will roll a radius completely to the end of the piece. After prep-rolling/forming these "starter radiuses, the additional material is cut-off and the the final rolling/forming takes place. the diagram that I have attached here hopefully explains this process a bit better than my word description. Best regards, Allan