The Secret Language of Saw Blades

Ever gone to purchase a sawblade and wondered just what all the codes are engraved on the side (or printed on the packaging)?

There are a surprising number of variables that are possible with saw blades, so many versions that can be considered.  Some are irrelevant when choosing between one blade and another – they distinguish between a blade suitable for wood vs plastic (for example).  Some blades do cross over – the Flai Mustang for example, which will have variables that suit both materials.

For example: ATB D250, K3.0 B30, Z40, H10

ATB

ATB = alternating top bevel – this blade has its teeth set so it is like a chisel, with one tooth cutting to the left, and the next to the right of the kerf.

You could have 4+1 (4 ATB teeth, plus one FT (flat tooth) as a raker tooth, flattening the bottom of the cut).  An ATB blade leaves a V groove in the bottom of a partial-depth cut, and the 4+1 is a way to resolve this, leaving a flat-bottomed kerf.

Other options include HATB (or HiATB), where the teeth are even more angled which is good for melamine, and timbers prone to tearout, TCG (triple chip grind, also known as triple cut, FT (Flat Top), HG (hollow ground)

D250

D stands for diameter – size of the blade in mm.  A 250 blade (or to be exact, a D254) blade is 10″

K3.0

This is the kerf of the blade, measuring across the teeth.  This does not mean the blade will actually cut a 3.0mm wide kerf however. Blades have runout (just how flat is the blade, and during use just how flat it remains as the temperature of the blade changes).  Saws (tablesaws or circular saws) also have runout, and it is a combination of both that will dictate exactly how wide a kerf you will get.  If you want to know it exactly each time, you have to measure it whenever you change blades.  The next time you mount the same blade, it could be different depending on at what point of rotation that the saw is vs the blade.  It is much easier just to do a test cut and remeasure if it is that important.  This concept is greatly (and deliberately exasperated) for a wobble dado blade, which is designed with a large amount of runout which can be dialed in, creating a dado (or wide trench).

B30

This is the size of the bore – the hole through the middle of the blade.  Depending on your saw you can either get a blade that specifically matches your saw, or one that is larger and get some saw blade bushes (or reducers) to match both the blade and you particular saw.  They are not as convenient (but are still easy to use), and they allow you to purchase blades that are suited to your needs without necessarily being made for the size bore you require.  Of course, if the hole is smaller than your arbor, you have a problem! Getting back to dado blades for a sec, when using stacked dados, I would strongly recommend getting one where the bore is correct for your saw – there are enough things to juggle without also having to try and manage a bunch of bushes as well.

Z40

Z stands for the number of teeth.  A ripping blade can have around at little as 24 teeth, a crosscut blade as many as 100.

H10

H is the hook angle (or rake angle). Large hook angles are an aggressive blade, particularly for ripping soft timbers.  Small, zero or even slightly negative for crosscutting hard timbers.

 

These are just some of the variables and codes that can be written (engraved) onto the blade.  They may not all be listed, and some blades may list a whole bunch more.  If you know these at least, you are well on your way of being able to distinguish between one blade and the next.

 

Some other variables include top clearance angle, top bevel angle, gullet size, gullet plug, expansion joints, noise reduction slots, max operation RPM, carbide type, base blade material, blade coating, body thickness and so on.  We’ll stick with the most common concerns at this stage!

 

Manspace Issue 2

The second issue of Manspace Magazine will hit the shelves shortly, and again with a number of articles by yours truly.

Articles in there by me are:

Quick Drawers – on how to make drawer liners for your tool drawers from foam

Torque the Talk – an article on the Torque Workcentre

Solution with Teeth – a look at the Flai Mustang multimaterial blade.

6 pages in total 🙂

Episode 58 Mustang Sally

Wild Horses – Mustang by Name & Spirit

Perhaps a bit of creative license, but the Flai Mustang is a very interesting blade to have mounted in the table.  More formally called a multi-material blade, I prefer to think of it as a Universal Blade.  Or a Jack-of-all-trades.

The Multi-Material Mustang

It can be mounted in your tablesaw, and cut whatever you decide (or accidentally include) for it to cut, and in particular when dealing with reclaimed timber it is easy to miss the occasional nail, and this blade doesn’t think twice about it.

There is a compromise in that – the teeth are designed to cut wood and steel (mild), but that will mean it is not going to achieve a perfect finish when compared to a dedicated blade.  In saying that, it will be interesting to see just how large, or small that compromise is when I put the blade through the battle-of-the-blades tests.  Given its other design and construction features, it could still out-perform many of the dedicated blades, but I’ll reserve my judgement to the tests.

Mustang Teeth

There is another compromise – it has a pretty small gullet, so in ripping, particularly material prone to generating long fibres, the blade is going to struggle if the feed rate is too high.  But once again, if it is a choice between running a Mustang through timber prone to have hidden nails and running a dedicated rip blade and finishing with shattered teeth, well it is a no-brainer.

It has a surface treatment they have coined the “MetalGear Coating”, which is claimed to double the cutting capacity of the blade, and allow faster feed rates.  To achieve this coating, Flai uses PVD (Physical Vapour Deposition), where the coating (in this case a nitride coating) increases the surface hardness around 5 times.  The actual “gear” pattern that they achieve at the edge of the coating is just marketing.  But it looks good 🙂

The carbide tips are brazed on using a silver-copper-silver alloy which provides a lot more shock absorption capability than a standard silver brazed joint.  This is particularly important for a blade designed to cut both woods and metals – absorbing the impacts that would otherwise result in microcrack formation (and when a microcrack grows, it finally results in the loss of a blade’s tooth).

So that is a bit of a look at the Mustang, a TCT circular sawblade with neutral hook angle and triple chip teeth, a universal blade capable of cutting wood, wood derivatives, nail embedded wood, plexiglas, plastics, non-ferrous metals and mild steel.

I particularly like that nail embedded wood bit – being freed of the thought in the back of your mind that there might be missed nails etc in the bit of reclaimed timber you are about to cut is quite a liberating concept. In the past, seeing the remains of a nail that has been sliced by a quality blade is not unlike finding half a worm in an apple you’ve just bitten.  With this blade it becomes a “eh, whatever, extra protein” moment!

SSYTC025 Flai Mustang – Universal Blade

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