Dado Stack Expectations

[Joe A Faulkner]

I'm cutting some large tenons for stretchers on a workbench build using a Craftsman dado stack. I'm surprised by how rough the finish cut is. I've not used the dado much in the past though I've had the blades for years. I'm curious to learn from some of you what your expereince is with your dado stack? The max width of this stack is 13/16ths which is what I have it set up for, the outside blades a cutting deeper than the chippers - maybe a 32nd or 3/64ths deeper. I'm able to clean up of course, but am curious, is this variance normal?

[Brian Libby]

My stacked dado does the same thing.

[George Bokros]

I have a set of C-Man stacked dado set they also produce cuts with the bat wings you speak of. I also have a Freud stacked dado set and they produce a much cleaner bottom of the dado. It all depends on the dado set.

To get a flat bottom dado you need to use a router.

George

[Charles Wiggins]

I'm cutting some large tenons for stretchers on a workbench build using a Craftsman dado stack. I'm surprised by how rough the finish cut is. I've not used the dado much in the past though I've had the blades for years. I'm curious to learn from some of you what your expereince is with your dado stack? The max width of this stack is 13/16ths which is what I have it set up for, the outside blades a cutting deeper than the chippers - maybe a 32nd or 3/64ths deeper. I'm able to clean up of course, but am curious, is this variance normal?

I have a stack set that I got years ago from Harbor Freight. It cuts pretty clean, especially in hardwood. The outer blades do cut a bit deeper at the outer edges - tiny angled trenches. I just look at them as somewhere for excess glue to go.

I'd like to upgrade to the DADONATOR! (http://www.infinitytools.com/Dadonator-8-Stacked-Dado-Set-With-5_8-Bore/productinfo/SDB-800/)

[Dick Mahany]

I use a Forrest dado set and it cuts cleanly in anything I throw at it. Cost was relatively high, but the performance has well been worth it. I've plowed dadoes in hardwoods, softwoods and even melamine surfaced particle board.

[Ray Newman]

Stacked dado sets are known to not cut the same depth, esp. the steel sets.

"Cure" is to have the complete set re-sharpened and tell the sharpening service that you want all the blades and chipper ground to the same diameter.

Easy fix by the sharpening service. When the blades need to be sharpened again, bring in the complete set and tell them the same thing.

[Howard Acheson]

>>>> all the blades and chipper ground to the same diameter.

Probably not the best idea. The outside tips on the outside blades are intended to cut slightly deeper so they product smooth dado sides and cleanly cut the the edges of the dado. Even the best dado blades will generally produce the "bat wings" because of the deeper cut.

That said, the best dado blades will leave less "bat wings.

[C Scott McDonald]

I have a forrest dado king and it does smoothish bottoms. Considering the inside blades only have two or four teeth it just isnt going to produce smooth surface. I generally cut a bit big and sneak up on it with a rabbit plane until it fits the mortise.

[HANK METZ]

If it's their ubiquitous HSS 6" stack dado, that's about all you can expect from it. I have their 8" carbide tipped set and it gives a much better cut, but hogging off the full width puts a tremendous strain on the saw. I rarely stack up more than 1/2" wide and simply make multiple passes to acheive my joint, the results are a yet more noticeable improvement in the finished cut. About the only time I ever go full stack is when making a dado for 3/4" thick stock, even then it's usually no more than a 1/2" deep shallow cut.

[Richard Coers]

What wood species? Cheap tools, bad results. Pretty sure Craftsman blades are not at the top of the heap for quality cuts!

[Frank Drew]

Those cuts are intended to reduce chipout at the edges crosscut dados, and in good sets don't amount to much more than a few scoring marks that don't at all affect the fit or gluing. If the chippers are themselves uneven and produce an up and down cut all across the dado, then the whole set needs tuning up by a competent sharpening service.

[Joe A Faulkner]

What wood species? Cheap tools, bad results. Pretty sure Craftsman blades are not at the top of the heap for quality cuts!

The bench is being built from hard maple. The depth of cut is only 3/8", but I am going full width for these 3" tenons. So far, I've only hogged out for the long bottom stretchers. The saw is an old Unisaw (1.5 hp wired for 220) and it isn't having any issues. I don't sense that dropping the width down to 1/2" is going to change things much. From what most have reported, it sounds like unless I spring for a high end dado stack, I can expect to need to clean things up a bit.

[glenn bradley]

I'm able to clean up of course, but am curious, is this variance normal?

You have probably figured out from the responses that a dado stack, like many tools, come in different qualities. Sometimes the cost even reflects the quality but, not always. My Freud SD-508 cuts very clean but, does leave tiny 'bat's ears' at the outside. These are insignificant enough to not bother cleaning up. I have a CMT set that requires some shoulder plane work if the dado is going to show. You can specify when you have your stack sharpened if you want to avoid the 'bat's ears', they just minimize the effect during the grind. This is a trade off. If you do a lot of veneers or fiberous woods like red oak or white ash, the same geometry that minimizes tearout, leaves the bat's ears. Right tool for the job and all that.