differance between a 6" and 8" dado=2"

[Tim Wagner]

OK, besides the 2" whats the differance? Generally speaking, you only need to go a 1/2-1" deep right? so is diamiter not that big of deal? is the Freud SD506 Dado an ok tool?

Thanks.

[David Weaver]

Someone who is more of an expert can come by and comment on why, but some table saws specify that they will only accept a 6" dado set. I've never tried to put an 8" dado set in one, so I don't know if the reason is mechanical, or if it's due to (lack of) power.

You could certainly spin a smaller diameter dado with a less powerful saw, but you're going to be getting less blade tip speed, too. My contractor's saw requires a 6" dado stack - and no bigger, but I could never find a throat plate for it, so I've never tried one.

Experimentation, or at least finding someone who has experimented, would allow you to find out if there is a significant quality difference in the different sizes of dado stacks.

[Scott Brihn]

Tim,

I have been mostly satisfied with the SD506. It makes flat bottom cuts although there is some minor scoring. In terms of 6" vs. 8", there have been a few times when I wish I had the 8" version. I often use a sled and there have been times where due to sled height, the 6" was a little short.

The case it comes in is great for storage. The stock shims are a little hard to get on/off the arbor but aftermarket slotted shims are available for nominal cost.

If I had to do it over again I would spent the extra $20-$30 and get the 8" version.

[Don Abele]

Tim, I have both a 6" and 8" dado set. I bought the 6" when I had a 1HP direct drive saw as that's what it said was the max. When I got my 3HP cabinet saw I found a great deal on a carbide 8" set, so upgraded to that. I have used by 6" set on my cabinet saw and saw no dramatic improvement in speed, the cut was cleaner with the 8" due to carbide vs no carbide on the 6". I think the only issue you are going to encounter is that of weight - need more HP to turn the extra two inches of metal.

Take care,

Doc

[Mark Carlson]

Tim,

I bought a 6in dado when I had my bench top saw. Smaller saws should use the 6in. I have a cabinet saw now but havn't upgraded to an 8in yet because the 6in does everything I've needed so far. With the 6in I get a max dado height of 1in. With the 8in I'd get 2in max height. I hope I did the math correctly.

~mark

[Charles McCracken]

Tim,

Actually the difference in diameter is 2" but the difference in cut is only1". The first step when deciding is to check the user's manual for the saw to see if there is a size limitation and abide by that. If you can use either the 6" or 8" your decision should be based on the power of the saw. Since the 8" requires 1/3 more torque to operate than the 6" you may want the smaller one for saws that run on 120 volts.

[Hoa Dinh]

OK, besides the 2" whats the differance? Generally speaking, you only need to go a 1/2-1" deep right? so is diamiter not that big of deal? is the Freud SD506 Dado an ok tool?

Thanks.

Will you cut half lap joints in 4X lumber? Will you use a sled when cutting dados/rabbets?

If yes, you'll be happier with an 8" set.

It's true that an 8" set has greater speed than that of an 6" set, so it's supposed to produce a better cut. But I doubt if anyone can tell the difference.

It's true that an 8" set requires more time and power to come up to speed, but afterward, there is no difference. The greater inertia actually helps in some cases.

If the cost difference is not significant ("significant" is very subjective), I'd go with an 8" set.

I used my Jesada (same as CMT) 8" set on my old 1 HP Craftsman and 1.5 HP Delta without any problem.

[Jim Becker]

"Tip speed" is faster for the 8", too, but if we are talking a good set like the SD50x, the cut difference shouldn't be noticably different.

[Charles McCracken]

It's true that an 8" set requires more time and power to come up to speed, but afterward, there is no difference. The greater inertia actually helps in some cases.
I hate to sound argumentative but this is not accurate unless you plan to let the dado just spin without cutting. As soon as load is applied the torque required to maintain the rotational speed is 1/3 more for the 8" than it is for the 6". Think of each tip as a lever with the arbor as the fulcrum. For the 8" dado the load is 1/3 farther from the fulcrum.

[Randal Stevenson]

The 6" dado's don't have the full range of the 8" dado's (width). As such, your smaller arbor (length, not diameter) saws generally require a 6" dado.

[James Carmichael]

Charles pretty well nailed it.

I will mention I briefly owned a direct-drive saw and spun a Freud 8" stack on it with no problem, though it might have mean't early death for the motor had I kept it.

Saws rated for 6" dado stack are usually limited by the throat opening in the dado insert. An 8" will work fine so long as you don't try to raise it higher than the throat opening allows, or else make your own dado insert. A saw like that may only have room on the arbor for a 1/2" stack, anyway.

[Greg Heppeard]

The rule of thumb that I've always used is: 6" for anything under a 3hp saw...3hp and over you can use an 8". I would only use a 10" in a 7hp or larger. (Yes...they do make 10" blades with a 1" arbor)

[Bob Childress]

Well, I have always used the Freud 8" in my Hitachi contractor saw and have never had a problem. Doesn't even sound labored. And I have cut some pretty deep half-laps, too. Maybe the blades are just that good, I dont know. :) (Of course, I go slowly.)

[Lou Ferrarini]

I use the 8" Freud SD608 set in my Delta contractor saw and my old Craftsman RAS. Works great and no bogging down.

[Tim Wagner]

well I just got the Pm2k up and running, so thats the saw I have.

[David Dundas]

Before I acquired a Domino, I used my 8" dado set for cutting tenons in a single pass with a table-saw tenoning jig (using a spacer between the outer blades in place of the chipper blades), and for cutting bridle joints. If your saw can handle it, I would definitely go for the 8".

David

[John Bush]

I used the SD506 with my 2hp cabinet saw and got excellent dadoes every time. I HAD to buy an 8" set for the SawStop, otherwise the 6"er was a great value. I bought the Dadonator and have been pleased with it as well. JCB

[Jeffrey Makiel]

Tim...that's a beefy saw. So power is not the issue.

I have both 6" and 8" dado sets for my cabinet saw. I bought the 8" dado because I thought that would make me a better man. It did not. :)

-Jeff :)

[Eddie Darby]

I have a 3 hp Jet cabinet saw, and I've run into 6" as being the max, and I've also run across 8" as being the max. Go figure. I think that the rule of thumb that Greg Heppeard gave is good.

"The rule of thumb that I've always used is: 6" for anything under a 3hp saw...3hp and over you can use an 8"."

If I was pushing the limits of my saw for any cut, then I would make sure that I had a sharp blade in it, to optimize everything in my favour.

[Mike Circo]

I exactly mirror Lou F.

I have a Delta contractor's saw that works perfectly with an 8" dado. I can mount, start and cut 3/4" dados with no startup or bogging issues.

But That is a quality saw. I suspect that very cheap imports, with discount motors, couldn't use a full 3/4" set without popping a breaker. Rule of thumb says 6" for contractor saws, but not every one needs it.

I wanted the 8" set for my secondary use in the RAS as the 6" set would cause the motor to sit so low to the table as to be difficult to use.

[Jim Becker]

Sometimes the limitation of 6" dado sets in contractors' style saws is due to internal clearance when the wider blade set is mounted. On some of those saws, an 8" set would hang up and be in contact with metal. Be sure to check on this if you are using that saw format before you buy the larger set if that is your preference.

[Tim Wagner]

This is all great info, thanks for everyones input. I guess if I am spending 2100 on saw, I can get a good 8" dado set. with that in mind can ya'll shoot me some name brands, er, i mean preferances.

I'll go put a couple more coats of wax on the baby while I wait.:cool:

P.S did i mention that I might get a magic molder too? :)

[Luciano Burtini]

I have used the SD308 (24 x 8") Freud in everything from my 1-1/2 hp Craftsman contractors saw to my 3 hp General 350 cabinet saw all with no problems. The Craftsman was close to the limit of arbor length with a full 3/4" stack, but no other issues.

Power was never an issue with the dado, even with the Craftsman which could be stalled while ripping 1" maple if you weren't careful. I don't think you could stall the General - something would break first.

The only minor annoyances were the very tight shim material on the outside blades (problem solved with a fine file) and I originally had one outer blade cutting a slightly deeper groove than the others. Freud rectified this problem immediately at no cost to me.

Highly recommend Freud SD series dado blades (as well as most of their industrial line saw blades). However I am also a firm believer in use the right blade for the job - sure would be nice to have two General 350's! Hmmm.