Marking of Sheet Metal using elementary geometry.
Sometimes you don't have the right tools to hand to mark out your plans onto the sheet metal, so using this elementary geometry and a simple engineering compass you can draw a line 90 degrees to a datum you have placed on the metal sheet. Alternatively you can use a pair of Scribers and engineering blue.
In these steps will show you how to draw a line 90 degrees to a datum.
Step 1) Draw a datum line (A to B) on the metal sheet.
Step 2) Draw a marked line (Point C) where you want the 90 degrees intersect line to be.
Step 3) Open your engineering compass halfway, and placing the needle on the intersect at point C draw an Arch from point D on the Datum line to point E.
Step 4) Open up your engineering compass fully, and placing the needle on point D, draw an Arch above point C from point G to F.
Step 5) Now placing the needle on point E, draw an Arch above point C from point H to I.
Step 6) To now finalize draw a line from the intersect point J to the Datum at point C, which is 90 degrees to the datum.
