Working with jigsaws

One of the first pieces of advice you hear when you buy a bandsaw is to ditch the blade that comes with it and purchase a decent one.

That rings true in many instances, as the supplied blade can be inferior and be detrimental to the machine, making you believe the saw isn’t all it should be.

The same can be said of other tools that reiy on peripherals to achieve their best, and with a jigsaw there seems to be more blades and configurations than you can shake a stick at, let alone cut.

A trip to a car boot sale, market or budget high street shops can often throw up so-called bargains, but with cutting blades you pretty well always get what you pay for, so a pack of blades for a quid is unlikely to cut cleanly or be as durable and sharp as a pack of good-quality ones will be.

But the price of a pack of decent blades can make us all baulk, so It’s easy to fall Into the trap of ‘this blade will do’ even if it’s a quality one, making do with one that is either not best suited, or has become blunt, and I’ve been as guilty as the next man in that respect, only to regret it after the cut has been made.

I’ve certainly cursed on occasion when cutting out a sink or hob in a worktop, only to find that the blade has drifted on the bottom of the cut, either making the bottom too wide for any retaining clips to grab, or too narrow to fit the sink.

Mind you, I have often fitted a new blade designed to cut wood only to then strike carcase fixings in the unit itself and ruin a blade in the process which, if it isn’t changed, will also cause drift problems — very frustrating, incidentally, I wish that the manufacturers who make the carcases for oven and sinks would redesign them so the fixings don’t sit near the cut-outs, but that’s another story..,

Jigsaw basics

With a blade for every occasion, it’s not only determining what one suits best, but Working with jigsaws the jigsaw itself has to be set up to suit as well; it’s a combination of the settings of the saw as well as the blade that give the best cut possible.

Pendulum action

With any cutting operation you’re looking to make life easier, so the less work involved after the cut is made, such as cleaning up or additional fitting with other tools, the better.

It’s unusual nowadays not to have similar functions on any jigsaw, even at the budget end, and it’s the pendulum action that is the deal maker or breaker for most of us looking to work in timber.

Older saws and some budget ones have no pendulum, but it’s a huge benefit to have a saw with one, both for the cutting performance in general and the longevity of the blades.

With a pendulum the function oscillates the shaft so that it cuts on the up stroke, while moving away on the down stroke — pretty much how we work a hand saw, pushing through the stroke to cut and easing off on the return.

If a jigsaw is operated without pendulum, the teeth are constantly in contact, so as you push the saw forwards, they are trying to cut on the downward cycle as well as the up, but only end up generating friction, and of course, friction leads to heat, heat leads to overheating, and the blade gets too hot and then starts to wander.

The pendulum can be varied though; most have three oscillating settings, so on its lowest position the movement is small. This gives a cleaner finish as the action is less aggressive, but the cut has to be made slower or the overheating problem can still arise.

The greater the setting the faster the cut, but with a greater setting the quality of cut diminishes alongside it, a factor that is more evident on veneered or laminate boards where splintering or chipping will occur.

Thinner stock, both timber and sheet, is better cut with a lower pendulum setting to keep the cut clean, and because it is thinner, the resulting cut is still quick, so there will be little need for a higher setting.

Likewise, the heat build up is lessened on thinner stock so you can turn the pendulum off for the cleanest of cuts, but I prefer to gain a smoother drive by using a low setting.

While a pendulum action is desirable in timber or timber-derivative sheet stock, the jigsaw is a very versatile machine, and cuts in both ferrous and non-ferrous metal are made without the pendulum engaged.

Working metal with a pendulum usually sets up excessive vibration, so the saw can jump and jerk around, plus cutting metal isn’t a fast operation like timber because the saw cannot be forced through in the same way.

Variable-speed trigger

But while a jigsaw can be pushed hard into timber, and with the right blade will cut very fast indeed, the control of the saw is almost as important as the blade and pendulum if you are looking to get consistency; it’s almost a balancing act.

For me that control includes a decent variable-speed trigger — not just for the variable speed to limit the top speed in general, but the trigger itself allows far more control of the saw, and if you look to operate a jigsaw in the same way as you drive a car, then assuming you aren’t a boy racer, that will also help gain consistency.

Think along the lines of slowing down or easing off the motor power going into and through a curve and accelerating as you come out of it and things work much better.

A variable-speed trigger allows this; easing off on the trigger as well as slowing the speed at which you move the saw allows the blade to clear the kerf cleanly without additional heat build up, and it’s on curves especially where a blade will drift should it overheat.

If you don’t have a variable-speed trigger but you do have a stepped dial, it’s the next best thing, so slowing the cut down In the same way is beneficial,

Good to have

Those, for me, are the really important features on a jigsaw, but swapping blades is commonplace so a decent tool-free system Is high priority as well.

It’s again unusual nowadays not to have such a thing on a saw, and while some are better and easier to operate than others, and not necessarily based on the price either, anything that speeds up blade swaps is.always a bonus.

Base tilting is common on all saws, but while useful it’s not an overly accurate function, A couple of top-end saws from Festool and Mafell offer interchangeable bases for bevel cutting, but for me a jigsaw is still not a saw designed for high-end accuracy in general, but a tilting base is nevertheless useful for undercut work and bevelling in general; a truly accurate fit would likely need further work with other tools.

Another useful, though not essential, attribute is a blower function to keep the kerf line free. Not all saws have them, but they do prove their worth if you don’t have any dust extraction.

Alongside this is a work light. LEDs are very bright and while these are quite a new introduction, they’re very handy for illuminating the work area directly in front of the blade, but prior to this there was a penchant for putting lasers in jigsaws. A laser on a jigsaw? In my opinion you may as well give a fish water wings for what use they are.

Handles and grips

The final point would be a personal preference of grip. There are two options: the more conventional hoop handle or the body grip.

Body grip saws are favoured in Europe where woodworkers tend to work from the underside of the workpiece, holding the saw below the work while watching the blade project through the surface.

It has advantages: the top face, which is normally the seen or face side, has no break-out as the jigsaw normally cuts on the upstroke, lifting the grain. Cutting from below, that break-out is now on the back, so if your control is good, the finished cut will be spot on and perfectly clean, but on the negative side, making longer cuts isn’t easy because you are restricted by your own arm length, plus you have to support the work to make the cut.

Work with a hoop handle and the saw is a lot easier to control, isn’t restricted by the length of your arm, and the job can be supported on trestles or the bench while you cut.There is the break-out predicament however, and that is where blade selection plays its part to minimise the problem, so time for a good look at the different types, and what they do…

Specialist blades

If you want to cut anything, chances are Bosch has a blade to do the job.

The Bosch-owned Scintilla factory in Switzerland makes blades not only far Bosch, but also for other major suppliers of quality blades.

Looking at how we work nowadays, there are plenty of specialist materials in common use that we come across as woodworkers, and while the woodworking blades remain constant , there are a lot of new specialist blades to match these new materials.

Granite substitutes like Corian are used for worktops, and while it can be cut with standard blades, it soon dulls them.

Bimetal blades are more durable, having a harder steel for the teeth bonded to a softer backer which extends the cutting performance that bit longer, also allowing you to cut through a variety of materials in one go, such as reclaimed timber where you can hit stray nails for example, or, as mentioned earlier, those sink cut-outs where the carcase fixings are always where you need to have the blade.

Blade for synthetics

However, there’s a special blade designed for Corian-type applications. The T301CHM for synthetics has a set of tungsten teeth bonded to the blade to cope with the abrasiveness of the materials being cut.

The longer life and suitability isn’t cheap, and on line I’ve seen them at prices ranging from £10 to £20 per blade! But with Corian-type materials highly priced and in need of high-quality finishing, the need for correct tooling is all the more apparent.

For fibrous materials

Another blade, this time carbide tipped rather than with a set of teeth bonded on, is the T141HM. This one is for fibrous materials, fiberglass reinforced boards, fire-check panels and the like. Again, these are commonplace in the workplace, and having cut fiberglass with other blades before, I know just how quickly it kills a blade if it isn’t designed for the job.

Blade for ceramics

Ceramic cutting, such as intricate tile work for example, has it’s own blade theT130. This one has been around for donkey’s years -1 knew it as a Riff blade, and it still carries that mark. It was the one we used for anything other than wood or metal and has a very coarse bond of carbide abrasive on its edge to grind rather than cut.

One for acrylics

Acrylics such as Perspex need a fine-toothed blade, but using one with any set will chip the edges, and when cutting some more brittle acrylics, will crack it, The T101A blade has no set at all, and a very fine tooth pattern.

To cut acrylic successfully you need to slow the saw down or it will heal the material through friction and melt it, but with no set the blade could easily still get hot.

Some are taper ground to give clearance at the back of the blade to counteract the heat and give It some clearance for curve cuts.

Knife-edge blade

For work involving soft materials, polystyrene, carpet, leather and rubber, a knife-edge blade is available.

This is certainly more an ‘industry’ type blade though I’d be reaching for the Stanley knife in most instances, but it’s good to know there’s a blade that does the business if you need it.

Metal-cutting blades

Metal cutting has its own characteristics, but as mentioned earlier, is best achieved with the pendulum off.

A basic metal-cutting blade such as the T118AF covers the general cutting ot common metals, steel and alloy alike.

Bi-Metal blades

Bi-Metal construction gives durability and also flexibility If you’ve used a hacksaw with a standard blade you’ll know how easy it is to snap them. Bs-Metal gives the blade flexibility so any catches in the cut won’t snap it. The same tooth design as a hacksaw blade is used; the wavy set provides blade clearance in the cut.

Aluminium can easily clog a metal-cutting blade as it is so soft and the tooth pattern quite fine. Therefore there’s a blade specifically for aluminium, the T227D, This has a traditional set that you would use on a handsaw, along with a sharp hooked an aggressive tooth form, widety spaced almost like a skip tooth, will give good kerf clearance as well as removing the waste from the gullets without clogging.

Cutting stainless steel

Stainless steel is a different ball game, In kitchen fitting it’s often a chimney hood that needs cutting to size, and using a standard wavy-set metal blade on it can damage it, leaving a poor cut. Also, the steel tends to be that bit harder so requires a special blade to cut it cleanly.

The T118AHM Inox blade is similar to the Synthetics blade, having a solid carbide tooth structure welded to the softer backer. This is slightly wider than the backer to give kerf clearance, but has no set so the cut is clean without the roughness a wavy-set blade leaves in the thin stainless steel it’s designed for. It shares the similarly high price characteristic of the Synthetics blade, but one blade can save heartache and additional expense, so is surely worth it in the long run.

Wood-cutting blades

With the specials’ out of the way, it’s wood cutting that has the biggest range of blades available, and with that go probably the biggest headaches as to what is best. Blades for specialist materials don’t need a huge range as the materials they cut are of known, consistent structure, so once decided upon, the optimum cutting performance is easily replicated.

Timber is of course very varied, with different grain structures, degrees of hardness and the uses we put it to all determining how we cut it, so the blades need to be designed to do that specific task.

Anyone who understands the basics of saw sharpening will know that by introducing more set, different tooth pitches and fleams, as well as the teeth per Inch, the saw will perform differently so jt can be altered to suit the work in hand.

Jigsaw blades for timber-cutting work on these same parameters so if you understand the basics of saw tooth geometry you are off to a flying start.

Good-quality blades usually have details on the packaging to indicate what their optimum cutting areas are, usually along the lines of the finish the cut will leave as well as the thickness of material it works best in.

Cutting thick material

Thicker material is an area where deflection or drift will occur more often. Some jigsaws may well be able to cut up to 150mm with a blade of sufficient cutting depth such as the T344DR but the chances of deflection are increased, especially if the saw is pushed hard or you attempt tight curves too quickly,

To try and counteract this, the longer blades are normally thicker to give them more chance of remaining on track, and usually come with a defined set on the teeth to give good clearance, but this is at the cost of the finish on the cut itself.

The back of the blade is also tapered marginally; though not the same as a full taper grind, this is just to allow St to rest in the Jigsaw roller guide correctly.

General-purpose work

For general-purpose work, the stock saw blade would have to be the T144D. It’s a smaller version of the T344DP and covers most bases when it comes to fast cutting in a range of timber derivatives as well as natural timber It has set and a wide tooth spacing for an aggressive fast-clearing cut on curves as well as straight work, However, using this blade, or indeed a blade with set on it designed for fast cutting on a veneered face board, plywood or a melamine top can cause excessive chipping and tearing.

On chipboard worktops, if the worktop is cheap, the bond between core and melamine can be prone to bigger tear-out and on an inset sink cut-out for example, can lift the melamine beyond the lip of the sink.

A finer-toothed saw without set is better although the cut has to be taken that bit slower to counteract drift and heat, but the resulting finish on the surface is usually excellent.

Full taper grind

For cleaner cuts in any timber application, full taper-ground blades are available. These are made in the same way as a premium handsaw, with the back of the blade taper ground to give kerf clearance without excessive set.

In the jigsaw blade for instance, there is no set, the taper is enough to clear and the cut is normally very clean. The tooth pattern on a standard taper-ground blade for clean cutting is still very aggressive, but unlike the blades that have set and are sharpened with a gullet or fleam that would be at 90° to the blade if it was hand filed; these have what would be described as a dropped file handle to give a very sharp point, almost needle like. It severs the fibres very cleanly and, on crosscut ply work especially, the splintering is minimal

The lack of set on the blade makes turning tight curves difficult as there’s little clearance behind the blade and it’s in this situation that you find the blade can easily overheat as it struggles to turn within the kerf and begins to bind. It also feeds back through the saw as vibration as the saw tries to kick back when the blade becomes trapped. The result is likely to be an overheated blade that drifts within the cut.

The remedy is to make relief cuts to gain clearance for the kerf around the radius or curve you are trying to make if you possibly can. It may be that you need both parts so cannot make relief cuts though. Of course, there are blades that are thinner to give a tighter turning circle, but that increases the possibility of drift and also the overall thickness of stock it can cut.

Jack of all trades

In general use the jigsaw often ‘makes do’ with a Jack-of-all-trades blade, the T144D. This is a fast-cutting wide spaced and set toothed blade for stock up to 50mm.

In many instances it does the job well, but its limitations are evident on face-veneered or laminate boards especially as the finish will tear and chip even on low pendulum setting.

Conclusion l have to say that with all the special blades available, and despite some being very expensive, if the job in hand needs it, getting the right blade saves time. If you work wood for a living, losing money due to the need for further remedial work resulting from poor, wrong or blunt blade selection Is prevented.

I’m still a pretty dyed-in-the-wool believer that a jigsaw is more suited to sheet stock and timber up to 50mm though, despite the deeper cutting blades available. They do work, but you need a good jigsaw to get the best from them, and even a good saw will give more vibration feedback from the increased workload so you need to be in fuli control to keep it from vibrating and moving excessively.

I think the biggest problem with jigsaws is education, I’ve mentioned I’m as guilty as the next woodworker when it comes to making do with the blade t have, or thinking it will go on a bit longer, but disappointments and additional need to rectify things has altered my work practice, especially on jobs where a blade is more prone to drift.

I actually threw away about 30 old bent, blunt and burnt blades i had hoarded in the jigsaw carry case as I had convinced myself they would go on a bit longer before it actually clicked!

I’m now a born-again jigsawer though. I put a fresh blade in when it’s an important cut, curse when I hit a fixing with a blade that isn’t designed for it, and swap over when I do so, albeit with a tear in my eye.

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