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Cutting a square hole? Answered

This is a really basic question—I have managed to get to 66 years old and still be a complete handyman novice, I have tried but my best efforts are lamentable. I think it is because I have never had anyone to show me handy things and have never asked anyone so turning over a new leaf I am determined to start making a few things instead of spending a fortune buying them and paying people to do things for me. My first project is to make a simple slide carrier and I have bodged one up in cardboard but it really needs to be in something stronger so it is rigid, metal would be ideal but very stiff board would also do if I can not cut the metal. I do have a thin sheet of aluminium, (from the casing of an old laptop) that I would like to use buy am frightened of messing up & worse injuting myself! I now realize that I have no idea how to cut a square hole in a piece of metal or, for that matter, what tools I need to cut aluminium in the first place!

My overiding consideration is to be safe so I don't want to try, (what to me is a daunting task but probably to you guys the simplest of things) not knowing what I am doing. So can someone please help me out and tell me what tools I need and how to go about cutting a square hole in a piece of metal? Rest assured I will not do it if I do not think I can safely.



Assuming you don't want to buy a lot of equipment your not going to use again, if the hole is inside the diameter of the biggest drill bit you can use - normally 10 mm or around 1/2 inch then drill the biggest hole you can and the file the rest of the material away - Aluminium is fairly easy to work.

1. Ensure you fix the metal sheet down when you drill DO NOT hold in you hand.
2. Go slow and drill a smaller hole first ti guide the bigger rill bit.

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. File the edges to the correct size after.

Thank you, that is the answer I needed. The square hole has to be slightly larger than a photographic colour slide so your last paragraph is the answer. Cheers.

Either a file, a milling machine, or a press

I'm not an expert on this, but I'd try a punch and die set.


I have a set of vice grip like pliers made for this that the punch and die slide onto. It goes through thin aluminum pretty easily.

If no one has one you could borrow, you could always use a punch to dimple the metal ( so your drill bit doesn't skate about), drill a hole and use a file to square off the hole. Much slower, much cheaper.

Best of luck!

Thanks for this, souns good to me. Could you clarify for me please, do you punch dimples all around the square & then drill to connect the holes? Cheers.

If its a large hole I'd Drill 4 holes and saw between them. (Use a file to square off the corners. If its smaller, dimple the metal with a punch, drill a hole with a small bit and the use progressively larger ones until its your target size and square off the hole with a file.

Two other thoughts... Go slow and use oil when drilling. A drill press helps a lot.

Clamp down the metal! If the bit catches, you don't want the metal plate spinning around. (Maybe obvious, but this happened to me when I was young and had to get a bunch of stitches n the hand holding the metal.... Clamps cheaper than stitches. :))

A hand metal nibbler could be used to cut a square hole. :

Drill  2 holes , placing them  in opposite corners of the square.
Each hole allows you to start  1 horizontal  cut and  1 vertical cut.

The holes should be big enough for the nibbler head to fit through.
I think 3/8 inch to 1/2 inch hole is usually big enough.

Just to add to the other answers: If the metal is not too thick, a fret saw is a handy tool. Drill small holes in the corners, saw from hole to hole and clean with a file.

If you're dealing with sheet metal, the previous answer (get a proper square punch and die) is correct. If you want to cut square holes through thicker materal (metal or wood), then you want a Watts Brothers bit. It's a triangular bit which cuts a square hole using an eccentric floating chuck.

Google square drill bit for more information.

Thanks for this, the "eccentric floating chuck" sound a bit daunting! But will have a look at it.

WAAY too expensive for a one off! damned clever tool though. You can get triangular, square and hexagon drills.