What Size Dado?

[Wade Samuelson]

I need a dado and see that they commonly come in 6", 7", and 8" sizes. I have a 10" contractor table saw (direct drive 3hp). Any suggestions would be appreciated.

Wade

[Chris Padilla]

Wade,

I have an 8" one (CMT brand) but, frankly, I don't think I've ever dadoed anything deeper than 3/4" so I'm not sure I need one that big. The 6" will be cheaper than an 8" for sure.

I'd love to hear the reasons for an 8" set over a 6" set. Perhaps more mass is more stable, less vibration? However, the cutters are further away from the arbor so I'm not so sure about less vibration. Since a 6" is smaller in radius, stopped dadoes can be cut closer to the end than an 8" dado so you have less to clean up with a chisel. I'm starting to reach here but I think a 6" set should be fine.

[Donnie Raines]

The smaller the HP on the saw..the smaller the dado stack. There is, surprisingly, greater mass when you step up to an 8inch set....thus the smaller saws would need to work a lot harder to turn. I have read that the breaking point 1 1/2 HP...below this go 6 inch or smaller...above this go 8 inch(if you want to). I had a few diffrent dado stacks over the years...some 6 and some 8. I could do everything I needed with the 6 that the 8 could have done. Like Chris pointed out...the cost for a 6 is less. many of the major brands out there carry the "nicer" sets in both 6 and 8 inch sets.

[Jim Becker]

Wade, with your saw...which is not really "3hp" despite the misleading labels...I'd suggest you stick with a 6" stacked dado set. It has a little less mass and some of the smaller contractors' style saws like the one you have sometimes have issues with fitting an 8" set due to interference internally when you have it stacked wider. And, should you ever upgrade to a larger/heavier saw, the same set will work just fine. Since the vast majority of dados one might cut are 3/4" or usually less deep...there is nothing lost by using the smaller set. For a more powerful machine, an 8" set will allow greater tip speed for a "potentially" cleaner cut, but in most cases, we humans will not notice a lot of difference.

Regarding the horsepower thing...if you look closely, it's probably indicated to be "peak" horsepower which is what is developed right about the time the motor fries. Normal operating horsepower is probably 1 -1.25 hp if it runs on 120v and draws about 13 amps or so.

[Ken Garlock]

... I'd love to hear the reasons for an 8" set over a 6" set.

Chris, the answer is simple, and the best example of the answer is any episode of "Tool Time." :D Now, where do it get that 30 hp motor for the TS? ;)

[Wade Samuelson]

Great! Again, thank you all very much. This place rules!

Wade