How to Cut & Fold Sheet Aluminium

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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Comments

[Oncer]

How thick was the sheet you demonstrated with? 1mm, 1.5mm?

Thanks.

[lingib]

The sheet was 18 gauge

[jinkypig]

mm is that 0.0478" or 0.0403"? :P Have I ever said I really detest imperial system?

at any rate, it is 1 to 1.7 mm? sounds about right. any thicker and it might be hard to score it deep enough to break it in a clean manner, ending up bending it instead.

[jinkypig]

Good one. we do that for acrylic but never thought of doing this for aluminium. What is the thickest aluminium you have ever managed to score and break?

[Quiggley]

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.

[badbeadgirl]

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

[jinkypig]

"American spelling" and "correct" are total oxymoron :D hehe.

but still, what can we do if people likes to bask their own error. :D

But yeah, despite my misgivings, you are right.

[Squirell2]

REMEMBER THIS EVER AGAIN: Use a thick plastic 'upside down T' shaped ruler with a knife. The mistake is to think that because you're cutting with a metal blade- you should use a 'flat metal' ruler, if you slip with the knife, need i say more?

[lingib]

Thank you for your comments and advice :)

From experience plastic rulers should NOT be used as it is too easy for the blade to dig into the plastic and run up over the top.

Plastic is also more slippery than a steel rule. A non-skid coating on the underside would probably help if you are considering thick plastic.

'T'-squares are okay but limit the maximum cutting distance. They are not suitable for trimming small pieces of aluminium due to the width of the square and the need for the handle to have a minimum contact length to achieve a right-angle.

For these reasons my preference is for a steel ruler. I find that you have complete control if your fingers are splayed and in contact with both the metal sheet and the ruler.

Metal rulers come in various thicknesses ... heavy gauge rulers are easier to control as they don't flex.

In ALL cases keep your fingers well away from the cutting-edge ... I lost the tip of my index finger in a wood working class at school when using a "marking knife" and "T-square".

[Squirell2]

Your RIGHT! yet's just make up a bunch of stuff about a "flat plastic ruler" rather than a 'upside down T shaped one'... then get into doing this properly: With a "Mini Metal Bender Brake." This ones a humble 18 Inch, they get a lot bigger. You can score with this unique Olfa knife for scoring aluminum sheet:
Thankyou for your time... And Good luck Bending things!

[MohanK30]

use ful tips. thank you,

[lingib]

You're welcome :)

[MohanK30]

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,

Mohan

[lingib]

This question appears to relate to the plotter described in https://www.instructables.com/id/CoreXY-CNC-Plotte...

I have posted a reply there ...

[slimtender.]

Interesting, for DIY works instead using a pro circular saw

[Jobar007]

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?

[lingib]

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.

[Konrad-der-Rote]

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

[lingib]

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.

[Konrad-der-Rote]

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.