How to Cut & Fold Sheet Aluminium





Introduction: How to Cut & Fold Sheet Aluminium

About: 55+ years in electronics, computers, and teaching ... now retired.

This instructable shows how sheet aluminium may be cut using nothing but a knife and a metal straight-edge.

A simple metal-folder, suitable for making small metal boxes and chassis, is also described.

Step 1: Cutting Aluminium Sheet

Sheet aluminium can be cut without the need for a guillotine or tin-snips which tend to deform the metal.

With the aid of a straight-edge and a sharp knife "score" BOTH sides of the aluminium sheet. This weakens the aluminium and creates a "fracture line".

Place the "fracture-line" over the edge of a table and bend the overhang SLIGHTLY downwards. Flip the sheet over and repeat. After a few "wiggles" the sheet will fracture along the cut-line leaving a clean break as shown in the above photos.

With care and patience full-size sheets of aluminium can be cut using this method. Create a long fracture-line then progressively bend the sheet from one end to to the other.

Step 2: Folding Aluminium

The metal-folder is made from two right-angle sections of metal. My folder is made from aluminium but "angle-iron" is okay.

The spacing between the two nuts and bolts determines the maximum width sheet that can be bent.

Prepare your work:

Mark where you want your bends.

Remove any unwanted corners.

Fold the aluminium:

Now slip the aluminium sheet between the two angle-s and roll the bender forwards while exerting downward body-weight pressure until the fold is 90 degrees.

Step 3: Corner Folds

Make a slot along one edge of your folder to accommodate the first bend.

Position the first fold such that it will enter the slot when the bend is complete.

Complete the bend.

The completed corner is shown in the last two photos.

Key point

When folding edges (see first photo) it is the edge that is placed in the bender ... not the sheet itself.

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    34 Discussions

    Dear Sir,

    Now I have completed the board. When I tested the operation, I found all good in either x direction or Y direction. When I try diagonal movement, the head part is not moving freely. it makes some rediculas vibration and not moving properly. What could be the reason ? due to Timming belt tension ? or the idler pulley tightness ?

    Please reply.

    Thank you,


    If you do an edit or re-write of this, you might change your spelling of Aluminum by removing the last "I" in your spelling. Thanks.

    1 reply

    "Aluminium" is the British word,
    "Aluminum" is the American word, both are correct.

    Interesting, for DIY works instead using a pro circular saw

    That's a really clever use of aluminum I-beam that's been cut in half. Did you make that yourself or find it in it's current state?

    5 replies

    I found a length of angle in a scrap yard many years ago and made it myself.

    Just cut two equal lengths and drill two holes for the bolts.

    I drilled the holes at least 25mm below the top edge so the full length of the bender can be used to form a lip when making radio chassis.

    The reason for so many slots is to accommodate different width radio chassis. I always bend the two longer sides then bend the shorter sides which means I need two slots.

    Could you post an action shot of the "Fold the aluminium" section? I'm having trouble visualizing it. Thanks!

    Try cutting the corner out of a piece of paper.

    Fold one edge up.

    Now fold the other edge upwards until both upturned corners meet, The reason for the slots in the bender edge is to allow the first upturned corner meet the second upturned corner.

    Thanks for the reply. Sorry, but I wasn't confused about the concept of folding, but rather exactly how to fit the sheet into and use the bender. I agree with Ghostrider513: a video would be very helpful, or at least some non-zoomed-in shots.

    That's awesome. Thank you!

    Glad to be of help. My post was not intended to be a criticism of your post. Having been in the fabrication industry and teaching welder/fabricators, as well as other engineering disciplines how to make things without 'ooops' results, I hope they are useful for other readers who are not aware of possible pitfalls.

    By the way. Our workshop definition of a skilled person was. 'Someone who could get themselves out of trouble before the management ever reaslised they were in it'!

    1 reply

    Your post was great ... it explains why I had difficulty bending an aluminium sheet some years back. Love your workshop definition :)

    A brilliant 'structable - and so simple.

    Maybe I can finally retire my panel saw and jigsaw from aluminium service!

    A point for the makers out there - the angle needs to be large enough provide the necessary leverage and support when bending the sheet - so larger than 25mm angle!

    2 replies

    The aluminium sheet used for the demonstration was 18 gauge.

    The angle was 1.25 inch (32mm) ... as you say you wouldn't want it any smaller.

    So probably 2" angle for 16 gauge (1.6mm)

    Happily, I don't have any need to bend anything thicker - 14 gauge aluminium only gets used for flat mountings and fascias.

    Sorry, like someone else mentioned I can't picture how any fold other than the first one can be completed. After you put the first fold into the slot, it looks like it would block the next fold and just be crushed in the corner. Maybe you are just *starting* the bend in your device, and then completing the bend outside of the device?

    1 reply

    Ok silly me I see now you're first positioning the fold over the slot and not in it. That first fold ends up in the slot after the bend is complete.

    For the 3rd and 4th fold, I presume you cut the corners just before folding. Do you normally cut the corners at this stage? I would've thought it'd be easier to do all the cutting first.