Table saw dado set diameter - 6" or 8"?

[Bretster]

A newbie question about what dado set diameter to buy. I am putting together tools for a teardrop project and am wondering if a 6" set for a 10" table saw is going to allow for deep enough cuts, or if I should go for an 8" set? I know I will likely use a router for many of my dado cuts, but can envision times when a table saw may be more efficient. My 10" saw has a maximum cut depth (with 10" blade) of 3 1/8". Based on that, maximum dado depth would be 2" with the 8" set and 1" with the 6" set.

Bret

[OP827]

I never needed dados deeper than 3/4", but I am not a professional carpenter. Now, I have 8" set simply because that is what was on sale, but 6" set could work fine too. The smaller the disk the less load on the saw motor. I often put thinner and smaller disks in my table saw as I can rip the wood quicker and more economically then.

[halfdome, Danny]

The 8” sets are the standard size, never knew there were 6” sets.
I have 2 sets and I now only use the set with full size chippers since they make the saw run with less vibration and a nicer cut.
I always make my dados shy in depth and use a clean out router bit to the desired depth.
Whatever size you buy make a special throat plate out of something like 1/2” Baltic Birch plywood.
Place some of the fence over the throat plate so you can safely cut the dado slot to the desired width and depth.
I have 2 Delta Unisaws and 1/2” works great but I screw in small screws in the corners to level it to the saw table.
Danny

[MtnDon]

Most dado grooves I have made for over 40 years have been no deeper than 1/2". The 6 inch dado set will do all that. Make or buy table inserts for a couple of different widths. Most good table saws should list the maximum size dado head. Some with smaller motors may not be as suitable for 8" dado sets.

I do prefer to use a router for cutting grooves and rabbets though. The bottoms of the cutouts seem cleaner. Slightly annoying to me is that some dado sets end up cutting "owl ears" in the corners of the groove because of the way the bade cutters are sharpened. You also have the option of using the router hand held with guides claped to the work. or with the router mounted to a good router table. More money for the router table of course, but I find a router table very useful for many things.

[Pmullen503]

I rarely use my dado set. A router is usually easier and faster to set up and use.

The one benefit a dado has is that you can adjust the width of the groove to fit your wood exactly.

With a router I'll use a rabbet joint instead of dado because the wood rarely matches the bit size exactly.

[noseoil]

I use the 6" "quick-set" type (carbide), has worked for years. 1/4" X 3/4" is the typical cut for cabinet panels...

[Bretster]

Thanks for your input everyone! My take-home from this is that I can use either the 6" or 8". I will see what I can find the best deal on and feel comfortable whichever diameter it is.

[aggie79]

A little late to the dance, but you also need to check the table saw arbor (spindle/shaft) to see if the threaded depth is sufficient for a dado blade. Some portable contractor table saws do not have sufficient arbor depth for a dado blade.

[Bretster]

Thanks! I have an older dewalt contractor saw which has sufficient arbor length to run a 13/16" dado stack.

Bret

[wannabefree]

Consider how much real horsepower your tablesaw can produce. A contractor saw may claim 3HP, but find out how many watts it consumes under load. It may not be easily available, but you can get a Kill-a-watt meter for around $20 and measure it yourself. Make the measurement while you are cutting through some 2x stock. Divide the watts by 750 and you will get a real approximation of the HP it generates. For example, a popular saw claims to produce 3-1/2 HP at 1200 watts. This is impossible. At best it will produce about 1.6HP. Once you have a number, if the real HP is less than 3, go for the 6 inch. The reason is the smaller diameter blade will require less torque to cut through the wood and there is a relationship between torque and horsepower. I can explain how they justify lying to us like this, but it comes down to marketing, and "everybody does it."
After many years of having my Sears claimed 1.5 HP saw with a 3/4 HP motor stall out cutting 3/4 maple with a thin curf blade, I bought a cabinet saw with a 5 HP motor. This saw slows down for nothing. I've cut some incredibly hard hardwoods nearly 3 inches thick with no trouble.