Manufacturing method for stage tube

A manufacturing method for a stage tube that has a first tubular segment and a second tubular segment bordering mutually and having different diameters, the manufacturing method comprising the steps of:

• a plate-preparing step:
• taking a metal plate that has a first segment and a second segment bordering mutually and having a first width and a second width, respectively, the first width being defined between two first paired edges, and the second width being defined between two second paired edges, wherein the first width is greater than the second width, wherein two of said second segments are provided, each bordering one of two opposite ends of the first segment, respectively;
• a first molding step:
• forming the first segment and the second segment so as to define a first edge interval;
• a second molding step:
• rolling up the first segment and the second segment so that the two first paired edges defining the first width of the first segment are jointed together and form the first tubular segment, while the second segment is formed to define a second edge interval;
• and
• a third molding step:
• rolling up the second segment so that the two second paired edges defining the second width of the second segment are jointed and form the second tubular segment.