Review By Dean Bielanowski  Northwood Tools Website - http://www.northwoodtools.com.au




Northwood 8" Dado Blade Set
 Review

By Dean Bielanowski

 

When it comes to creating dados, grooves or rabbets/rebates (whichever you wish to call them) there really is no quicker way than to cut them on a table saw using a specialized dado cutting blade set, particularly if you need to cut more than one. While you can also cut them with a router, the table saw and dado set can slice them much more easily and can cut deep dados or grooves in one pass with no issues of material burning or rapidly dulling router bit edges due to excessive heat.

Many saw blade manufacturers offer dado blade sets, the best being offered for many hundreds of dollars for a set. Sometimes as much as $400-$500 a set. For the budget-conscious woodworker, finding a quality set under $200 can be a challenge. The Northwood Dado set does come in under the AUD$200 price range, but can it produce high quality, flat bottomed cuts in a wide range of material? Let's find out.

The Northwood Dado Set
The Northwood set is an 8" stacked dado set featuring two outer cutting blades, and five inner chipping blades. The set ships in a very nice, heavy duty aluminum case with inner foam padding. This is perhaps the best Dado set case I have seen from any manufacturer so far. It protects the blades and tooth edges very well in transit or storage. A thumbs up there.

Inside you find the blades, and the teeth of each blade are protected by clear plastic tubing. This ensures, at least in this case anyway, that the blade teeth were damage-free out of the case and ready for use. Also included is a packaged set of round brass shims that are used between the blades to fine-tune the thickness of the set when installed on the table saw arbor, and hence the thickness of the cut.

The set has a 5/8" arbor hole, so they can only be used on table saws having a 5/8" arbor, and on an arbor that is sufficiently long enough to accept the dado set as well as the arbor nut to secure everything in place. Some table saws are not designed to use dado sets, and hence only have short arbors. The table saw I use, which is a TSC-10HB Taiwanese-made saw will accept up to a 3/4" wide dado set, but only just! The Northwood set will allow you to cut dados or rebates from 1/4" wide, through to 3/4" wide, and using a combination of chipper blades and shims between the two outside cutting blades, you can set virtually any width of cut in between 1/4" and 3/4" as well. It is like owning many different width straight cutting router bits, but at a fraction of the cost.

The blade bodies are all manufactured from heat treated steel alloy. They do not have special anti-rust treatments like some other higher-priced sets do, but for the lower price, there has to be compromise somewhere. Thankfully the carbide quality on the teeth is one area where no real sacrifice has been made. The teeth feature fine C-4 micrograin carbide, which will stay sharper longer and be more durable as opposed to more coarse grain carbide used on low-quality saw blades. The outer cutting blades feature teeth with a bevel grind facing in toward the kerf of the set, while the chippers have the characteristic, and necessary, flat top bevel grind, which allows the stacked set to cut flat bottomed dados and rebates.

Speaking of the outer blades, each blade offers 42 cutting teeth in a set combination that resembles what a good quality combination saw blade might offer. The teeth are arranged in 6 groups of 7 teeth, with extra clearance between each set, presumably to allow better removal of debris from the cut, particularly when cutting rebates or dados with the grain of the wood. The combo-style configuration makes these outer blades very effective cutting in pretty much any grain direction.

The chipper blades, which are always positioned between the two outer cutting blades, work almost like a chisel to punch, or chip out the middle material of the dado or rebate. The set includes four 1/8" chipper blades, and one thinner 1/16" blade. Using a combination of number of blades and sizes allows the wide range of cut widths to be achieved as mentioned above.

Setting Up A Dado Set
Setting numerous blades up on your saw arbor correctly is important to ensure a good quality cut and eliminate any chance of damaging the blades. When set on an arbor, the cutting teeth actually overlap each other slightly from one blade to the next, so the cut is properly and completely made. As a result you need to offset the location of each blade's teeth in relation to the blade(s) next to it. No teeth from different blades should be parallel to each other, because this would damage the teeth and you would likely find the blade bodies (being slightly thinner that the tooth width) would not be sitting firm against each other. For safety and accuracy, the blade bodies need to be snug to one another on the arbor, and properly secured with the blade arbor nut so they cannot move or rotate on the arbor when the saw is spun up. So, as long as you make sure all blade bodies are snug to one another, and that no teeth from the various blades are touching each other, you should be good to go.

If you need to slightly alter the width of a dado, use the round brass shims supplied. These slide on the arbor in between blades to widen the whole set by the desired shim thickness amount. The best way to measure the overall set thickness is to measure the distance between the outside edges of the cutting blades teeth with a digital thickness gauge. Or, perhaps better yet, find some scrap and make a test cut for fit or sizing first before running your project material through.

The Northwood Dado Set in Action
The sign of a good dado set is in its ability to create accurate, flat-bottomed dados with minimal vibration in use. I tested the set on a wide range of materials, from softwoods to hardwoods and composite materials (MDF, plywood and chipboard etc).

I set the blades up to make varying cuts from 1/4" through to 3/4" and at varying depths. Bear in mind that an 8" dado set can cut deeper than a smaller 6" dado set because of its blade diameter. Usually though, in most projects, you will rarely find yourself cutting any deeper than 3/4 of an inch, but if you do need to make a deeper cut, it is good to know you have the extra blade capacity there to do so.

To ensure the most accurate cuts and to test the flatness of each cut, I used featherboards and hold-downs on the workpiece to ensure the material was kept tight to the table and guide fence. I know the arbor on my particular saw runs very true indeed so there would be little effect of arbor runout on blade cut quality in this instance.

To begin with, when setting up the blades, I found the blade bodies were flat and fit together on the arbor quite snugly. This is a good start. The fit of the blade on the arbor can also affect the smoothness of the bottom of the dado. The Northwood set was slightly loose on my arbor, in comparison to one of my other dado sets. This made it much easier to add and remove blades, however, the bottom of the cut, as you might see below, was not perfectly flat, but for all intensive purposes, I still consider it a good cut. Upon starting the saw up I looked for excessive vibration, both visually and audibly. Both checked out ok. No real sign of blade wobble when the saw slowed to a stop (this is usually where you can notice it the easiest) and I didn't notice any excess vibration over and above what I usually expect from my table saw (which is very little to begin with).

During the cuts I made a note to check for excess noise coming from the blade. Usually, high quality, sharp blades will exhibit very little excess noise under load, whereas poorer quality blades can generate a lot more noise, usually because the blade may not be running true and cutting more material as it moves from side-to-side every so slightly. The Northwood set appears to run very true on my saw and with no more noise (as far as my ear can tell) than my best dado set I have used for many years. I was quite surprised in fact, given the lower cost of the set. I would normally have expected to find something noticeable in this area, but subjectively, there was not any discernable difference.


Bunny ears are hardly noticeable unless you look very closely.

What about bunny ears? What bunny ears? You know, those little triangular "notches" that are created on the outside edges of dados caused by the beveled grind of the outer blades, and often slightly deeper than the flat bottom middle of the cut. Some call them rabbit ears, and I have even heard them called Batman ears. These are very common with many dado sets. Even my better sets exhibit the slightest hint of rabbit ears. The Northwood set is not totally immune to this side effect. However, like my better sets, the bunny ears are very small, and not really noticeable unless you are looking for them. There are less noticeable ears than with one of my sets that cost twice as much.


Here you may notice the lines in the bottom of the cut, indicating perhaps the chipper
blades are not all the exact same diameter, or perhaps it is the slightly loose fit of the
blades on my saw's arbor? It is difficult to tell which. Nonetheless the error appears more noticeable in this photo than it does in actual application and fit.


The Northwood set creates flawless and sharp edges on melamine panels and all woods.

Overall Results
Results were the same across all types of cuts and materials. Apart from the slight deviations in the bottom of the cuts, the edges were all very cleanly cut and with minimal chipout on the backsides as the blades left the material. I did find making a dado along the grain, particularly in softwoods, produced a smoother cut than with crosscuts. Perhaps as to be expected, but worth noting nonetheless.

The set is very well balanced and it slices nicely during the cut. Not a lot of pressure is needed to move the material through the blades, indicating sharp cutting teeth and efficient debris removal by the chippers. rarely did we encounter any burning of material either.

The Northwood Dado set retails for AUD$149.99, which, at present, is less than half the price of a popular named brand set in Australia. I wont claim this set is as good as perhaps the Infinity Dadonator, but the Dadonator is priced at close to twice as much.

For the budget minded, the Northwood set is a good start into the world of dado blades, and if the fit of the blades happen to be slightly tighter on your arbor, its very possible you could achieve very flat bottomed dados or rebates with this set. It is certainly far easier and much faster to cut dados on the table saw than it is with a router, and with only one dado set, you can do the work of many sized router bits. The dado set is certainly the most economical way to cut dados, grooves and rebates, and the Northwood set makes it affordable to just about anyone who needs to perform these cutting tasks.

Available to Order Online through these companies...
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In the USA


 http://www.northwoodtools.com/product.asp?pID=11&cID=5

In Australia


http://www.northwoodtools.com.au/product.asp?pID=735&cID=383

Northwood Dado Set Photos
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Handy storage case makes transportation easy and, more importantly, protects blades during storage.


Chippers in one end, outer blades in the other.


One of the outer blades with 42 teeth in groups of 7.


The tooth arrangement helps clear debris more effectively.


Full body chippers with 6 cutting teeth each. Here are the 1/8" and 1/16" chippers.


Brass shims allow fine and micro adjustment of cut width. These are placed between blades as required.


The Northwood dado set installed in my tablesaw. Here it is set up for a 5/8" width cut.


This is why its called a stacked dado set! Notice the chippers are offset to each other.

 


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