TOOLS: How to cut sheet metal with air

Sheet metal is difficult to cut. The key is obviously to have a good tool.

I've tried with metal jigsaw: yes you can cut sheet metal with jigsaw but vibrations are very high, you need a powerful tool and a good support to the sheet metal. If something goes wrong (the cutter lock to the sheet metal while cutting) you will have a dancing sheet metal on your hands, so be really careful and use personal protections.

I've tried another option: AIR NIBBLER


You can buy the nibbler online for only 30 bucks, but you must have a good air compressor:

• it consumes a lot of air, in my experience something like 250 l/min or 8.9 cfm.
• it requires an high pressure (minimum 6 bar or 90 psi, up to 10 bar or 116 psi).

If you don't have a powerful compressor, you have to stop cutting and wait for the compressor to refill. Cutting with a lower pressure may lead to lock the punch in the sheet metal, which is difficult to release.

The product itself is a heavy piece of metal equipped with a reciprocating stamp punches (replaceable).

I was impressed by the power of the nibbler, which allowed me to give a straight cut to a 24 gauge sheet metal (0.6mm).

The cut quality is high, there is no deformation and the side is clean.

Vibrations are also low, because the piece of sheet metal is tight fitted by the head of the nibbler.

You can follow a hand curved path, but with the use of a supporting bar under the sheet metal you can follow a straight line without pains. To have the same cut quality along the line, is necessary to maintain cutting speed without halfway stops and tool perpendicular to the the sheet metal surface.

Another advantage is you can cut open pockets starting from a side, or closed pocket starting from a hole, just like a jigsaw.

While cutting on the front side a lot of little half moon pieces of metal are throwed by the nibbler, so also with this tool use a good pair of glasses, gloves and protect your skin: nobody should stay in the path of the tool.

DIY Sheet metal bending brake

While ago, i built a sheet metal brake from scrap. The design is simple and effective.

To build it you only need:

• Three pieces of L profiles, equally cutted (In my bender 3x1 meter long or 40 inches);
• One robust weld-on hinge (splitted in half use a piece for the left side, and a piece for the right side);
• Two pieces of threaded rod (25cm or 10inches);
• Minor profiles for the supporting stand and for the lever;

I've only used an angle grinder to cut the pieces and a MIG welder to compose the sheet metal bender. This tiny sheet metal brake can easily bend a large sheet metal of 1.5mm (3/64") or a narrow (5cm or 2") but thick bar (5mm or 6/32").

I'll improve it soldering on the back side two removable and adjustable stop bar to hold the upper L profile in place: while bending also an horizontal force is applied and sometimes the friction force applied vertically by the threaded rod is not sufficient.

The only drawback with this kind of sheet metal bender is that you cannot bend on four side, only on opposite sides. If you need to build a box you have to assembly it in two pieces, like the model in the photo:

The bending lever arm is 60 cm or 23 inches, and is sufficient to apply the right force to bend the metal.