Dado Set...6" or 8" ?

[Jason Quick]

So I'm kicking around buying a dado set....got some built-in cabinetry to build soon and I'm too lazy to route that many dados. What's the functional difference between a 6" and 8" diameter dado set?

Jason

[Jim Becker]

The size, weight and cost. Functionally, you'll find nearly zero difference since most dados are no deeper than 3/4" or so. And if you have a saw with a smaller motor, swinging the 6" set will be easier, too. (Some contractors' style saws specify nothing larger than a 6" dado set, too, due to internal clearances)

[Charles McCracken]

Points to consider:

With an 8" the cut depth is 1" less than with a 10" blade and with a 6" it is 2" less. As Jim said, most dadoes and rabbets will be 3/4" or less so 6" will handle this.

Some saws will not accept an 8"

An 8" requires 33% more torque to run than a 6".

[Brian Triplett]

Jason,
I asked the same question when I brought my dado set. I ended up with the 8" set because I knew I was one day going to update my tablesaw. At the time I brought my set I had a portable dewalt tablesaw. It actually did pretty good job with it. now my unisaw does a much better job don't get me wrong, just keep in the mind the future.

[Stu Ablett in Tokyo Japan]

I agree with the 6", but I did buy the 8", I see no need to have the 8", and if I did it over, I'd have bought the 6".

Cheers!

[Jim Davenport]

I use an 8" "Forrest Dado King" on my 10" Jet contractors saw. It given me years of great service. I've never had power problems with the 1.5Hp motor with it.

[Jarrod Nelson]

8" Freud Safety Dada (sd308) on my Delta 36-441 contractor saw. I've never had a problem with any cut.

[Frank Chaffee]

Points to consider:
… …
An 8" [dado blade] requires 33% more torque to run than a 6".

Charles (and any other engineers who may wish to respond),
While I can understand how this formula (HP=Torque x RPM/63,000) applies to power transmission where a chain, belt, or gear is used, I have to ask how it applies to the tablesaw blade where the Surface Feet per Minute of a larger diameter cutter also becomes proportionally greater. At the same feed rate the cutters on the larger blade advance less far into the work, and therefore the load on each cutter is lessened. (? Yes or no?)
Just thought while we are on the subject it’s a good time to bring this up.
Frank

[Charles McCracken]

Frank,

I am a technician, not an engineer, but torque on a circular blade is determined as if the tooth were a single lever pivoting on the arbor which is the fulcrum. On a 6" blade the load is 3" from the fulcrum and on an 8" it is 4" away - 33% increase. The inertia of the tips on the 8" would be greater but so would the force required to maintain the rotational speed under load. Tooth load would be more a factor of tooth quantity: more teeth = less load.

[Frank Chaffee]

Thank you Charles,
Frank

[Scott Loven]

I have a 6 inch Jesada dado that I use on my sears contractors saw. Works fine for what I need.
Scott

[Silas Smith]

I bought the 6" dial a width Freud. I have upgraded to a Uni so I could handle a 8" easier but the 6" has more than enough for my needs. I can't imagine needing a 2" dado. It is a little easier to handle, as far as putting it on my saw, but if you are the type that always wants bigger and better, get the 8".