How to use chisels instead of files to cut a share hole for carriage bolts.
Making a sqaure hole sheet metal.
Now it s time to use that center punch.
Use your center punch to strike at the center of the hole.
Go slow and drill a smaller hole first ti guide the bigger rill bit.
Put your ink to the use and mark the hole center.
Next use a compass to outline the edge of the hole.
At first locate the center of the whole.
This will create dimples in the sheet.
Ensure you fix the metal sheet down when you drill do not hold in you hand.
Insert the broach and ensure it lines up at 90 degrees from the work peice or the hole will be crooked.
Use a hydraulic press to gradually and smoothly increase pressure until the broach is forced through.
How to make a square hole without using special tools.
Drill a hole in the metal close to but smaller than the finished hole size.