Cutting Metal

Whether you’re making brackets to hold a piece of sound gear in place or forming a new panel, unless you’ve got a tame metal fabrication workshop around the corner, there’s one aspect that will always confront you – cutting metal.

So how easy is that, you’re saying? Grab a hacksaw and whammo!, a few seconds later the metal’s cut.

But if you’re someone who spends time actually doing this you’ll realise that all isn’t as easy as it seems. Like, how often has that hacksaw wandered off line and you’ve had to discard that piece of material? Or if you’re heavily into electric jigsaws, how long did that metal-cutting blade actually last? Or, have you tried a nibbling tool – something that opens up completely new possibilities.

Hmmm, maybe there is a bit more to this than first meets the eye!

Hacksaws

The simplest way of cutting metal is with a hand hacksaw. But you’ll also need a vice (vyce), a pair of eye protectors and some lubricant.  What’s all that stuff for? The vice holds the material rigidly in place which (a) reduces majorly your chances of breaking blades, and (b) lets you cut much more accurately. The eye protectors and lubricant? Well, read on...

• Place the material in the vice so that that its longest side is horizontal (assuming that the vice jaws open wide enough) and then start the cut on the furthest side. Putting the material in the vice like this (rather than the more common vertical orientation) makes it soooo much easier to cut accurately along a line. Always use two hands to control the saw and use a slow, steady motion. One-handed high-speed cuts more often than not will end up with the badly-cut material in the trash can!

Use a high quality blade. For years I used ‘whatever’ blades – then one day when I was feeling rich, I selected a packet of 12 very high quality blades. A year later I am only on the third blade from the pack – whereas with the cheapy blades I would have used the full dozen by now, easy. And the cutting has been far easier and more accurate, too.

Lubricate the cut. A spraycan of penetrating lubricant is fine but much cheaper is an old tin part-filled with auto trans fluid. Use a small paintbrush to wipe a smear on the metal where you will be cutting and you’ll be amazed at the difference.

Wear eye protectors. Even the cheapest dollar-pair of plastic goggles offer you far more protection than nothing at all. And the way that hacksaw blades can shatter, you need that shield between your precious eyes and those razor-sharp bits of flying, hardened metal.

A hacksaw and a good vice allow you to make accurate cuts in material up to about 100mm (~4 inches) wide. That’s enough to make brackets and heatshields, cut off bolts and brass fittings, and do the myriad of other cutting tasks that fall to hand when you’re modifying a car.

Materials? For the fabrication of brackets, flow directors, faceplates – and all of those hundreds of metalworking tasks that you come across – I am a fan of aluminium (aluminum in the US). Aluminium is easy to ‘work’ (bend, cut, drill, file, sand), it doesn’t rust, it looks good either painted or unpainted, and it’s light. It’s usually not suitable for heavy duty uses (unless specifically cast or welded) but it’s a great material for home mods. The stuff’s cheap, too – if you head to your local non-ferrous scrap metal dealer and look through the aluminium scrap bins. Extrusions (eg angle or square or rectangular tube) can be very useful offcuts to get (if making a bracket, the shape means that they’re already mostly preformed) and long narrow strips in addition to sheet offcuts will prove useful.

Electric Jigsaws

If you’re cutting circles (eg to put speakers in a door panel) or making long cuts, a hacksaw will be about as much good to you as a turbo on a battery scooter. Instead, it’s common to reach for an electric jigsaw. Dead-cheap (as all power tools are these days), an electric jigsaw can make intricate cuts with ease. But it can also dent panels, wear out blades at an incredible rate and is a damn easy tool to do both damage to yourself and what you’re cutting.

The material must be clamped so it cannot move. Obvious, huh? Not really. In this case, ‘cannot move’ means both laterally and longitudinally (ie it can’t slide around) and also vertically, in the direction that the blade is cutting. If the metal is built into the car, you’ll be concerned only with vertical movements – the easiest way of stiffening the sheet material is to clamp (or temporarily screw) a piece of plywood of MDF to the panel that you’re cutting. This will allow the power tool to much better impart its energy to the work piece – the blade will actually cut, as opposed to just vibrating the material up and down. If you’re working with a loose piece, clamp it to a workbench - even an old kitchen table is much better than nothing.

Electric jigsaws can be bloody dangerous tools, especially when working on thin sheet metal. The dangers came from three sources: (1) Don’t cut through the power cable (keeping it looped over your shoulder helps avoid this), (2) Make sure that there is sufficient clearance under the workpiece for the blade, and (3) Wear eye and ear protection.

You need to use a blade that suits the material. I know that this point applies equally well to hacksaws but – between you and me - you can really get away with cutting nearly anything with a general purpose hacksaw blade. But not in an electric jigsaw. Very thin metals can be cut with abrasive blade – one with fine particles of cutting compound adhered to the blade. (This avoids the chatter than occurs with even fine-toothed blades.) Other blades should be matched to the job, as indicated on the blade spec sheet.

Use a heap of lubricant, especially if you’re not cutting in a straight line. Quite often an electric jigsaw is the tool of choice because you’re cutting tight radii, and in these cases using lots of lubricant makes an astounding difference. As was said above with hacksaws, you can use penetrating lubricant spray but cheaper is an old tin of auto trans fluid and a small paintbrush.

Always wait until the jigsaw blade stops before withdrawing it from the work. This saves the blade bouncing on the uncut surface.... Which is always a downer when those dents will be in full view!

Nibblers

Nibblers are available in power and hand tool configurations. Probably the best compromise is to get a nibbler that attaches to a normal power drill. Nibblers are safer and easier to use than jigsaws while still being able to negotiate sharp corners. In fact, on uneven material (eg a heavily pressed inner door panel) a nibbler will be far easier to use than an electric jigsaw. However, nibblers are limited in cutting depth – you can’t make a hole in a bonnet and cut straight through the supporting ribs like you can with a jigsaw.

Either clamp the material and move the nibbler, or clamp the nibbler and move the material. Good nibblers can be used either way, the choice depending on the size of the material piece and whether it’s a part of the car or something that you’re adding. The width of the cut made by a nibbler is much greater than by a jigsaw or hacksaw, so always mark the side of the line on which you’ll be cutting.

Be careful not to overload the tool. If the die and cutter are to have a long life, you don’t want to feed a heap of material like stainless steel through a nibbler. Yes it will cut it but when the cost of the replacement bits is much higher than for jigsaw and hacksaw blades, better to keep the nibbler for thin steel and aluminium sheet.

Use lubricant. (See above!)

 

• Nibblers are safer than both jigsaws and hacksaws - but still wear eye protection.

Cheap Power Tools? Secondhand stores, tool discounters and even the tip – they’re all good places to find cheap power tools. In the case of electric jigsaws, look for those designs that are variable speed and take a wide variety of blade types (rather than just brand-specific blades). But doesn’t cheap = bad? Not really, not if you’re an average occasional-use hobbyist. Just don’t expect the jigsaw to last 10 years... which is fine, considering the price that they’re available for!

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