Substitute for Dado Set

[Terry Mac]

I knew a guy from my hometown, a little farm town in Oklahoma, that would put two, and even three saw blades together on his table saw as a substitute for a true dado set. Recently, I came upon an internet discussion where a guy did the same thing (table saw and RAS), and espoused the virtues of doing this, instead of spending money on an expensive Freud Dado Set.

Here's the question: Is this safe? If so, what about dust expulsion and clogging up among the blades? Any thoughts or comments?

[Don]

Hey, Terry. Good question. I've done the same thing at times for different reasons. First off, a real dado head has the "set" of the teeth arranged in such a way as to allow them to miss each other when stacking, obviously to keep from bending the blades when tightened and to allow for complete material removal. Also, dado heads are "topped" to allow a flush bottom cut. The diameter of is also usually smaller to allow for the increase in torque required to turn through the wood, also the smaller diameter allows for closer blind dado cuts.

That being said, a blade is a blade. If the saw has the power, the teeth are not interfering with each other, you like the result of the cut; it will do in a pinch. Chances of you having a set of blades that are the exact diameter will be slim and well as having blades with teeth that miss each other. If you stacked four 10" x 60 tooth carbide blades on an arbor and tried to tighten them you would bend the discs too much and most likely damage teeth that could come loose at speed.

When we've done it in the factory it was for a dedicated setup and we had the blades ground together. Say we needed a 1/4" (two blades) groove for cabinet backs, the larger diameter gave us longer life, a better cut, and kept us from buying complete dado heads and tossing aside the chippers.

But, if you are going to stay in the trade/hobby I would suggest either obtaining a true stackable or one of the better wobble head dados. The wobble heads are ground so they give a good flat bottom at a 3/4" setting, but they tend to chip out more than a stackable though and a tight fitting throat plate really doesn't solve the problem with these.

A good dado head can last you a lifetime, I've never worn one out beyond sharpening.

“Here's the question: Is this safe?” – If you are an experienced woodworker you can best judge your setup for yourself, if you are a novice I would have to advise against it. Dado work can be dangerous just by its very nature; there is an increase in the danger of kickback, there is an increase pressure to feed material, guards are usually removed. Try to always use push blocks where applicable. If you are a novice, routing might be a better consideration.

“If so, what about dust expulsion and clogging up among the blades?” - Dado heads have fewer and more separated teeth. This helps keep material from becoming stuck between teeth and ejecting the greater amount of dust. Not a huge problem though with stacking a couple of blades.

Anybody else have thoughts?

dawjr

[Dagster]

Some tooth patterns may allow you to do this without chipping teeth but the cost of doing a 3/4" dado (6 1/8" kerf blades) with saw blades would far exceed the cost of a decent dado set.

[Jerry]

I have an inexpensive stack dado from Horror Freight. (I stole that name) Cost about $30 a few years back. Works way better than I expected! When cross cutting plywood, you get a little splintering. I have used a knife to cut the verneir before dadoing and prevent splintering.

[Don]

I've seen the name used here before as well. It's not the tool, it's the guy using it . . . well sometimes.

dawjr