A smaller blade will require less horsepower to cut with (cutting speed is slower) so it might be more appropriate for a saw with less power. I think that if you are cutting wide and deep dadoes with your saw, and your motor is 1 1/2 HP or less that you should consider the 6".
While this certainly makes sense from a physics point of view, my 1.5 HP saw has no trouble spinning a 3/4" wide dado into oak with an 8" stackable on it. Granted I'm not going deep, but something tells me it could if I needed to.
Hi Tom. In addition to the depth and power answers, also consider rim speed. The 8" set will be travelling at about 82mph while the 6" size runs at about 62mph - at 3450rpm. That's akin to dialing down a router from 22,000rpm to 16,500rpm. Many (as in most) woods will produce a cleaner cut at the higher speed.
I bought a Freud 8" 24 tooth/4 tooth chipper set (the SuperDado, I believe it's called), years ago back when I had a Jet 1.5hp contractors style saw and never ran into any problems with it bogging down on normal depth dados in hardwoods or half-laps in 2x materials.
I don't know if the 6" would have performed just as well, but I've had no problems with the 8" set - and it's always nice to have that extra depth should the need ever arise - tho it hasn't arisen for me yet.
I think you could be happy with either - perhaps let cost factor into your decision. I ran a 6" in a benchtop and now run an 8" in my contractor saw. The 8" can cut deeper, but it's a capability I've not needed yet.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.