Abstract: Sheet metal having an opening therein includes projections adjacent to the opening. A column to be mounted at the opening has a slot therein for engaging the projections. The column has a threaded axial opening which is engaged by a screw located within the opening of the sheet metal. The opening may have a tapered portion with the projections located thereon.A tool for shaping the sheet metal with an opening therein is also disclosed. The tool includes a member having a first end to which a force may be applied and a second end with at least one radial projection. A seat is provided for receiving the second end of the member. The sheet metal is shaped by placing the opening over the seat, locating the second end of the member within the opening and sheet and applying a force to the first end of the member.