Ensure you fix the metal sheet down when you drill do not hold in you hand.
Making a sqaure hole sheet metal.
How to use chisels instead of files to cut a share hole for carriage bolts.
At first locate the center of the whole.
If the hole is a lot bigger then your biggest drill bit then drilling holes round the edge of the square and then connecting them with a saw is the best way for you.
Next use a compass to outline the edge of the hole.
Making a square hole in a plough blade.
Now it s time to use that center punch.
Drill a hole in the metal close to but smaller than the finished hole size.
Put your ink to the use and mark the hole center.
Blacksmithing for beginners cutting a square hole in sheet metal.
Use your center punch to strike at the center of the hole.
Use a hydraulic press to gradually and smoothly increase pressure until the broach is forced through.
Insert the broach and ensure it lines up at 90 degrees from the work peice or the hole will be crooked.