Way of the Dado

The dado blade – taking a standard sawblade, and deconstructing it into its various elements.  Then taking one of the fundamental variables of a saw blade and making it variable, making it controllable.

Normally, we accept (and suffer) the kerf (the width of cut) of a sawblade.  When you cut a piece of timber, the kerf is wasted timber – it is turned to dust and sucked away.  The thinner the kerf, the less material is wasted, and the less power the saw requires to drive the blade.  But then, the thinner the teeth (more susceptible to damage, and less resharpening opportunity), and the more flexibility of the blade.  It seems the most popular kerf is 3.2mm.

However, there are times when you want to have width to the cut.  If cutting a long slot (a dado, slot or trench depending on your country’s definition), then doing this on the tablesaw is a lot faster, and puts a lot less load on the machine than trying to do it with a router bit.  So the dado blade is one where the alternating top bevel is now on different blades (a left and a right one), and the chipper teeth are on chipper blades that sit between the two outside ones.  By adding additional chipper blades, the kerf of the assembly can be increased, and then finetuned with thin shims.  This obviously cannot be done with router bits, so now the dado blade has two advantages over completing the same job with a router bit.

A router bit can plunge and cut a stopped dado, a dado blade cannot, and there are other instances when using a dado blade is not the method of choice.

But when you want one, they can really do the job quickly, easily, and repeatably.  So long as they are a good quality set.  So far, the dado sets I have used have been a disappointment when it came to testing them, so rather than run through all the potential variables if this set (the CMT 230.524.08 8″ 5/8 bore to suit my specific saw, from Carbatec) can cut a decent trench, it will be the winner – all the others I have tested so far have been rejected.

Here I have assembled a 16mm dado stack, mounted in my tablesaw and already plunged up through a wider insert that I made for my tablesaw from MDF.  The maximum size dado the set can create is 25.4mm (1″), but this is wider than my particular tablesaw can cope with.

The blades are 1/8″ each (and you must use both for all setups) so the minimum dado width is 1/4″  If you use all the chippers and the shims, you get the maximum dado size of 1″.

The chipper blades are 1x 1/16″, 1x 3/32″ and 4x 1/8″

The shims are 2x 0.020″, 2x 0.012″, 2x 0.008″ and 2x 0.004″

I also chose the 5/8″ bore version to match my current setup.  Most of my other blades have a 30mm bore (from memory) and then use an insert to get them to match my saw.  But if I was to try that here, I would be juggling one for each outside blade, then one for each chipper.  Too much stuffing around just to future-proof a dado set.  And I’m not planning on upgrading my tablesaw any time soon (not unless a SawStop Pro or Powermatic  falls into my lap!!!)

My tablesaw is 10″, but I’ve chosen to have an 8″ dado set.  That might seem strange – why not get a dado set that matches the capacity of the saw?

This is actually a very common practice.  A normal blade is only 3mm wide, and if it takes a significant proportion of the saw’s power on the most testing of cuts, what would it mean if you tried to spin up a dado set that could weigh 5 – 8 times as much, and then push that thickness through a block of timber?

So a smaller diameter blade is significantly less weight to spin, and even the splitters are weight-reduced with portions selectively removed to decrease the power required to drive them.  Even so, this set is no-compromise.  The splitters are 4 tooth on a full disk.  Some dado sets have very limited splitters, more like a airplane prop than a blade.  Not sure which I’d prefer, not sure I care (other than 4 teeth are better than 2)

The biggest reason for going for a lower diameter blade?  You don’t need bigger!  This is for dados, not for sawing timber in twain.  And creating a zero-clearance insert is much easier and safer when the blade can be wound down into the table far enough that it fully clears the bottom of the insert.

Not the best photo, but you can clearly see the outside blades have a combination of bevel tooth and chipper, and the chippers in the middle only have chipper teeth.  Also, you can see that the width of the chipper teeth is not important – it is the thickness of the body that determines the full stack width.  So the wider teeth make for overlap, to ensure they fully clear out the slot.

Setup for the dado cut.  The fence is locked down and the timber held against it with the latest featherboard from MagSwitch (the reversible featherboard on the universal base).  The guard and splitter are removed – cannot be used with a dado, or partial depth cut.  A zero-clearance insert is in place (shop made) and the blade set for the depth of slot required.

Setting the dado height, you have to be careful NOT to measure to the height of the bevel teeth – they do cut deeper than the depth of the slot as you will see in the next photo.  You measure to the top of the chipper teeth.

But the final truth is simple: can it cut a decent slot with a flat bottom or not?

Yes, it can.

You can see how the bevel teeth cut a bit deeper at the edges – not ideal (although pretty normal for dado sets).  It ensures there is a sharp, sliced corner rather than a rougher chipped one.  That’s not a bad thing – only matters at all if you are going to see the end of the slot at all (and you can see it is pretty minor even so)

This slot took no time at all – it really demonstrated to me just how useful a dado set is if you have a fair few slots to cut – blows routing them completely out of the water.

So the bottom line.  This CMT dado set is a win (as is the storage case personally – industrial, tough, and functional).

The CMT 230.524.08 8″dado set, from Carbatec.  This has a 5/8″ bore.  For the 30mm version, it is the 230.524.08M

The Rabbit of Caerbannog

Otherwise known as “The Grand Rabbet” (Probably better known as the “Legendary Black Beast of Aaaaarrrrrggggghhhhh”, but that is another matter).

Grand Rabbet

The kit from CMT (sold in Oz by Carbatec) consists of a 2″ rebate bit, and 16 different sized sleeves to produce a wide range of rebates, with a final sleeve with a matching diameter to the bit itself, turning it into a giant pattern copying bit. There is also a packet of spares for the actual double bearings, spacer sleeve, washer and hex bolt that are used as part of the assembly.


Working from left to right, you have the 2″ rebate bit (which is obviously of significant size!!), heavy chunk of carbide on each flute and a decent shear angle as well, so the bit creates a slicing action rather than a straight chipping one (producing a better finish/less tearout).  The first bearing is then added, along with the spacer sleeve (this fits in between the two bearings, and sits in the middle of the rebate sleeve).  You then have one of the range of rebate sleeves to choose, depending on the size rebate required.  A second bearing fits in the top recess of the rebate sleeve producing a very smoothly operating product.  The is capped off with the washer and hex bolt to lock everything onto the router bit.

Rebate Set

One of many different setups, this one produces a rebate (rabbet 😉 ) that is 2″ – 1 3/8″ = 5/8″ / 2 = 5/16″

Or if you prefer, 50.8mm – 34.92mm = 15.88mm / 2 = 7.94mm

You need to divide the answer by 2 to get the final rebate depth.

17 different rebate variations, plus the flush trim in the kit as provided.

So in the immortal words of Tim, the enchanter, I give to you “Well, that’s no ordinary rabbit.” The Grand Rabbet from CMT.

Tim, the Enchanter

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!

Blade Storage

I was initially thinking of titling this entry “Blade Care”, but I’m aware that this is not the best way to protect the blades, so will keep that title for the refined solution!

Blades should be stored vertically, and since the inaugural “Battle of the Blades“, I’ve had them sitting in their boxes on a shelf, which is not only less than ideal as far as blade care is concerned, it also makes accessing the blade that you want somewhat frustrating.  I was looking around the workshop, looking for some wall space for tool storage, and happened upon the cupboard doors.  They can only take a moderate load, so were not suited for the tools I wanted to relocate, but it dawned on me that the doors were not a bad solution for hanging blades.  So that’s what I did.

Blade Storage

On the left are 4 CMT blades from Carbatec – from top to bottom there is a thin-kerf combo, a rip, combo and crosscut. Below that is the extremely mean looking Linbide Rip, and at the bottom is an old Triton sanding disk (that mounts on the saw) that I used to fill the final gap.

On the right are 4 Freud blades from Woodworking Warehouse – from top to botton there is the Freud Industrial (still my favourite blade), followed by a rip, combo and crosscut Freud Pro.  Below that is the Linbide Combo (the blade most likely found on my tablesaw), and the Linbide 100 tooth crosscut.

A Bodyblow to Triton

It only takes an image sometimes to cause much doubt in the minds of long-time Triton supporters, and this one as first mentioned on the Woodworking Forums was one of those.

Discovered on the CMT website is this:

CMT7E_home_EURWhat do we make of it? Did the patent ball get dropped so anyone can make Triton routers, or was the patent sold to CMT?  In any case, it looks that the Triton router, regarded as one of the best table-mounted routers anywhere is no longer the (sole?) property of an Australian company.

CMT have already added and subtracted some minor mods to the original design – they have stayed with the original dial selector for free plunge vs geared height modes, but have added the through-table winder from the MOF001.  Wonder if they stayed with the nylon threads for the microadjuster?

They look to have gone with the Triton US collet.

There is something different at the back of the cap that holds the plunge spring – perhaps removing the need for a screwdriver to remove the cap?

Manufacturing is claimed to be in Italy (the Triton was manufactured in Taiwan), and the motor is 2000W, not 2400W

But the biggest difference is it no longer says “Triton” – it is now branded CMT Orange Tools.  What in the world has happened? How can Triton’s router – one of the pinnacles, one of their greatest successes have been given up?  The original 2400W saw went, replaced with a Chinese model – is the same happening with the router?

A Night at the Opera

Or more like, a night in the shed 🙂  Got a number of things done out there which was very refreshing, and actually felt like real woodworking for once. I even got to make some sawdust!

As I’ve mentioned before, I’ve had some trouble with my current inadequate power supply to allow me to use dado blades on my tablesaw. As a bit of a test, I purchased a tradesman’s extension cord yesterday which has a 1.5 mm core rather than the standard 1.0 mm (or even smaller) in typical household extension cords.  I plugged this feed directly into the tablesaw, and gave that a try and the difference was quite remarkable. Even running a standard blade, the saw sounded somehow different.

I then fitted a dado blade, and this time I was successful. The saw easily managed to bring the dado set up to speed. I must admit, that it has been a while since I’ve been that nervous around woodworking equipment- the first time you use a dado set is scary!  When a typical blade has lots of whirling teeth looking for something to eat, like a circling shark, a dado set looks like a whole school of sharks, and they know what they want.

On the other hand, it sure makes cutting a trench or a dado easy! (Funny that).  This dado test is going to be very interesting, and I’m now in a position to start testing the various blade sets that I have.  There have already been some irregularities come to light, so that is what this battle of the dado blades is all about.  One set appears to have the wrong outside blades, as the tooth count is incorrect to match with the chipper blades so that they cannot stack correctly (and I’m getting some feedback from the relevant company about that), and the set I used last night (CMT) had a very poor trench, because one of the chipper blades is over 1mm oversized which I was very surprised about with a set costing over $400.  Anyway, all this will be revealed in full Cinecolor in the reviews in the near future.

Next, a very rusty demonstrator got to shoot the raw footage for Episode 41 of Stu’s Shed TV which briefly covers some of the jigs that can be used on a wetstone sharpener.  I did get a very respectable edge on my carving knife, so the next tomato will pay the price in the kitchen!  I’ve said it before – the Triton sharpener should come with a knife jig – it is the best excuse to justify buying a tool ever!

Then finally, and inspired by my article about the Chris Vesper Joinery Knife, I had a further play with that laying out some rudimentary dovetails, and that inspired me to (finally) assemble the Dovetail Master I got from the Australian Wood Review over a year ago.  I had put it into the “too hard to think about now” basket, but last night everything just clicked.

Dovetail Master

Dovetail Master

It comes disassembled, but it isn’t actually that hard to put together.  Of course the proof will be if I actually can use it to produce a handcut dovetail, but it looks like I managed to assemble it without too much drama.

Disassembled Dovetail Master

Disassembled Dovetail Master

It is currently on special for all of $35 from Australian Wood Review (direct link to the product) fwiw.

So it was a good night – some sawdust made, some video shot, some old jobs completed.  Good times 🙂

The Rejuvenating Properties of The Shed

Did I ever need yesterday (and a whole heap more required, but I’ll take what I can get!)

Took a day off work yesterday because I really needed a bit of time out to recharge the batteries.  Not to sleep (although with a 20 month-old, sleep is a thing of the past!), but just to ground myself – my blood/sawdust ratio was obviously getting periously low!

And I had (and have) so many things to play around with.  I could take a week and not break the back of everything that could be done, but even a day out there sure helps.

There will be a few item-specific posts about the individual activities, but overall the day went such:

Unloaded the new tools down to the workshop. New tools? GMC are being very supportive of my activites which is very cool, and so there are some new tools to review, and use both in my workshop, and at courses I run etc, such as the upcoming toy course.  (Still looking for bookings for it (through Holmesglen), but there are going to be lots of ‘toys’ to play with, while making toys to play with!!)

So I had a Triton 3 in 1 to get down there, and boy, is that thing a monster.  Not physically large (still a reasonable size), but it feels like it has been carved from a solid lump of steel.  61kgs to be exact.

I also had to (sadly) pack up the Excalibur EX21 Scroll Saw that I have been reviewing for the next edition of the Australian Wood Review magazine.

Once there was a little space, I also had a small GMC benchtop drill press to assemble, the GMC 18V AllNailer to unplack and charge, a CMT Dado set (on loan from Carbatec), and I think that was about it.

Not sure about the AllNailer as yet – the first few nails I’ve driven, some have easily gone full-depth, but others don’t seem to have been able to penetrate to much more than 20-30mm of remaining nail.

I tried cutting a wheel with the 1/3HP GMC drill press (I’m hoping the Triton one will become available soon), and although I managed a 50mm one (in pine), it sure struggled.  The stalling was one thing – that’s just a fact of life that I was pushing it a bit hard, but each time that I did (and I did stall it often), I had to wait 30 seconds for the coil’s thermal cutoff to reset.  I’m guessing what was happening was – each time the motor stalled, the coils in the motor would get hot (immediately), and that there is a thermal switch in there that was tripping.  However, it is a VERY sensitive switch, so even a brief stall was too much for it, and the saw wouldn’t turn on again until the coils cooled.  Interestingly, the first side of the wheel went easily, and it was the second side that was problematic.

Once play time had ended, I went to work on a few prototype parts for a child’s table and chair, including trying out the Mortise Pal for making loose tenon joints using the router (rather than something like the Festool Domino (which looks great, but is miles out of my budget)).

So that’s a bit of an overview of the day.  I’ll go into more detail of the individual events later.

At least I feel a little refreshed.  More needed!!

Episode 32 Battle of the Blades

CMT 271.250.43M Thin Kerf

CMT Thin Kerf Combo

The next review from the “Battle of the Blades”. The CMT 271.250.43M Thin Kerf, 42 tooth combination blade.

CMT 285.048.10M

The next review from the “Battle of the Blades”. The CMT 285.048.10M, 48 tooth combination blade.

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