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 = 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)


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


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).


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.


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.


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!


Flai Router Bits

After experiencing what the Flai blades can achieve particularly with respect to finish, and therefore the quality and sharpness of the carbide I was rather interested to see what their router bits could achieve, and I wasn’t disappointed.

They don’t have a particularly large range of profiles sadly, but what they have does work particularly well.

Flai Router Bit

The carbide has quite a leading (shear) angle, so it is slicing rather than just chipping, and that will have some bearing on the result. In addition, the relief angle (back of the carbide) is also pronounced, producing a sharper leading edge. It is a variable-profile grind (at least that is what I’m calling it), where the relief grind is not just at a flat angle off the back of the carbide, but instead changes direction to match the profile, keeping the resulting angle consistent as the profile direction changes.

The shaft has been lasered, including the brand, and also the maximum router speed. (In this case, 18000 RPM)


Running the bit through a typical Australian Hardwood – Jarrah, and the result is shiny without tearout – a “Real Smooth Shave” (noone ever seems to get my movie references, or that there are movie references that get included in some articles, so here’s a hint!!)

The Flai bits have a “FlaiArmor” coating which is an excellent friction reducer, is anti-adherent, diffuses and disperses heat, and is stable in water and solvents.

Imported into Australia by Promac, and available through supplies such as Carrolls Woodcraft Supplies

Router Bit Kick

On a bit of a kick at the moment, each router bit is like a new tool because they work so differently one from another – some do edging, some shaping, some copying, rebating etc etc.  And there are so many interesting ones out there 🙂

Some that have recently caught my attention, and will be covered individually shortly are some Flai bits, to see how they perform compared to the brands I am currently useful.

Computer Depiction of a Flai Router Bit

I haven’t tried the Flai bits yet – I have a couple, and will be interested to see if they, and particularly their edges perform as well as their saw blades.

Double Rebate

This bit is one of the new ones in the Carbatec range – a double rebating bit.  It is used for picture framing, as it cuts a rebate for the glass (either 3mm or 6mm depending on which of the 2 you choose), and a second, wider rebate for the backing board.

One very useful addition for bearing guided bits is a set of bearings of different sizes.  This allows fine-tuning of how the bits work, increasing their versatility even further.

You can buy a set of bearings – there is a set in CMTs range for example

791-703-00 Bearing Set

But for the price, there is a better way: a rebate bit that includes a set of bearings.  The CMT bearing set is $77, for $22 more you get the full rebate set.

835-001-11 Rebate Set

However, what really caught my eye (when I was shown it by a friend) is

The Grand Rabbet Set

835-503-11 Grand Rabbet Set

Now it may not look as impressive in the photo here, but that is in part because you don’t have a scale reference.  The rebate (or rabbet in American) bit itself is 2″ in diameter.  What’s more, those are not bearings in the box – they are a kind of sleeve.  And the concept is significantly cool.  Instead of having a whole set of actual bearings in the range of sizes seen here (which would be very expensive), these are solid, machined sleeves that fit a bearing top and bottom so they run exceptionally well. The bearings themselves are replaceable (if it ever is needed) at a comparatively low cost.

With the cutter at 50.8mm (2″), there is also a sleeve that is the same diameter, turning the rabbeting bit into the largest flush-trim bit/pattern copying bit that I have ever come across.

Looking forward to getting to try the kit out – bring on the rabbet stew!

Episode 74 Flai U Blade

Episode 74 Flai U Blade

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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