Hi, I think you are talking about rolling not trying to make straight bends, right? Straight bends on square tubing are a mess, not to mention weak. If you are wanting to make a roller to make curves in square tubing (called a ring roller) there was a posting a while back in the main section of the forum.

http://www.homemadetools.net/forum/r...s-videos-32681

Hope this helps.