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Question about new Dado Set Flatness

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Forum topic by nek4life posted 06-29-2020 12:54 PM 403 views 1 time favorited 15 replies Add to Favorites Watch
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nek4life

28 posts in 494 days


06-29-2020 12:54 PM

Topic tags/keywords: question tablesaw

Is it normal to have these little wings when using a dado set? This is my first dado set and I made some test cuts (and messed up a work piece! DOh!) last night and noticed that the bottom is flat, but the edges stick up a little bit more. I’m assuming it’s to get a clean cut on the edges of the material without chip out, but since it’s my first set my expectations would be that the whole thing would be flat.

I’m building a small hardwood cabinet and was going to have exposed dados on the ends of the shelves so it’s a little annoying. I was also hoping to use this set for box joints and the like.

This is the set I’m using https://www.amanatool.com/658060-carbide-tipped-prestige-dado-8-inch-dia-x-24t-h-atb-5-8-bore-complete-dado-set-with-six-4-wing-chippers.html I bought these because they had good reviews and I could buy them at my local woodworking store.


15 replies so far

View Murdock's profile

Murdock

151 posts in 3261 days


#1 posted 06-29-2020 02:38 PM

That is totally normal, as you said those “ears” are there to prevent chipping.

I find that in most cases it is unnoticeable in the finished product. While I prefer the table saw for dados in the few cases where those ears may be noticeable I switch to a different method of creating my dados. (usually a router)

-- "Anyone who has never made a mistake has never tried anything new." - Albert Einstein

View Davevand's profile

Davevand

179 posts in 1613 days


#2 posted 06-29-2020 02:44 PM

Yes, that is normal for a dado set, the outside blades are tapered and slightly oversized to reduce tearout, commonly referred to as “bat ears”. I am a bit surprised that the Amana dado set has that much of a taper. Most of the better dado sets have a much less noticeable bat ears.

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Murdock

151 posts in 3261 days


#3 posted 06-29-2020 02:45 PM

I just realized you mentioned you wanted to use this for box joints, the few times I have done those I didn’t use my dado set for this reason.

I used a flat grind blade and made multiple passes. I know some people use a router for that as well, and I also have seen box joint sets where they don’t have those ears.

-- "Anyone who has never made a mistake has never tried anything new." - Albert Einstein

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CaptainKlutz

3197 posts in 2272 days


#4 posted 06-29-2020 02:55 PM

There is a ton of threads on the topic of flat bottom dado cuts?
Such as: https://www.lumberjocks.com/knotscott/blog/18046
and more.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View Fred Hargis's profile

Fred Hargis

6249 posts in 3270 days


#5 posted 06-29-2020 03:00 PM

It’s as you surmised and described by some of the answers above. It is normal, and that gives a clean cut….especially on the thin veneers that some plywood has these days as well as crosscut dadoes on hardwood. Some sets are worse than other, and it seems like I read that the Infinity Dadonator leaves the least noticeable of the bat ears (devils ears, wings, whatever you prefer).

-- Our village hasn't lost it's idiot, he was elected to congress.

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SMP

2132 posts in 683 days


#6 posted 06-29-2020 03:13 PM

For that project you may want to look at “housing joints” also called “stopped dado”. Even people that can cut perfect dados by hand will use that to cover up the joint.

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nek4life

28 posts in 494 days


#7 posted 06-29-2020 03:33 PM



For that project you may want to look at “housing joints” also called “stopped dado”. Even people that can cut perfect dados by hand will use that to cover up the joint.

- SMP

I’m definitely going to look into that. It would certainly give a cleaner look!

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nek4life

28 posts in 494 days


#8 posted 06-29-2020 03:34 PM

Sounds like the “bat ears” are normal and maybe I should look into a few more techniques or ways to hide them if they are going to show or try a different technique if I want them through if the “bat ears” bug me. I’m sure I’m the only one that would see them in the finished project. BUT THEY ARE THERE! :D

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Fred Hargis

6249 posts in 3270 days


#9 posted 06-29-2020 04:30 PM

there is one more alternative. You can buy flat bottom dado “clean up” router buts. With them you would cut your dado a less shallow than you want, say maybe 1/16”, then run the clean up but with your router. These are flush trim bits with a very shallow cutters, so you just run them down the dado and the make it the right depth and leave no “devils ears”. I believe they were developed to solve the very thing you mentioned (of course, taht’s speculation on my part). Anyway, here's one brand.

-- Our village hasn't lost it's idiot, he was elected to congress.

View AndyJ1s's profile

AndyJ1s

331 posts in 532 days


#10 posted 06-29-2020 05:52 PM

When using a router to cut or clean up a dado where the end of the dado will show, use a scrap backer piece on the end (where the bit will exit the cut at the edge of the board) when making the cut, to prevent tear-out on that edge. Some folks that build and use a straight guide for cleaning up dados with the router, incorporate the backing piece into the cleat on the end of the guide.

-- Andy - Arlington TX

View AlanWS's profile

AlanWS

57 posts in 4335 days


#11 posted 06-30-2020 02:23 PM

Freud and a few others also make a box joint set of tablesaw blades. This is a pair of blade that can be nested one way to cut a 1/4” groove and another way for 3/8”. It cuts a perfectly flat and square groove with no bat ears.

https://www.rockler.com/freud-box-joint-cutter-set

-- Alan in Wisconsin

View bilyo's profile

bilyo

1112 posts in 1880 days


#12 posted 06-30-2020 02:57 PM

IMHO, you are make far too much of this. Those “bat ears” are very small. Once they get filled with glue and finish, you (or, at least, no one else) will ever see them. I suggest you use one or two of your test cuts and glue in a piece of scrap. Then finish the edge as you will for the finished project. Then ask others (not yourself) if they see anything objectionable. Then judge for yourself. Having said that, I certainly agree that a stopped dado is a good alternative.

One other thing you might try is to put a drop or two of water at the edge where the “bat ears” will be exposed. Make sure the wood fibers in the little groove are saturated. Let it dry over night and see if the wood swells and, at least partially, has closed up the “bat ear” grooves. This might ameliorate the problem.

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shampeon

2119 posts in 2961 days


#13 posted 06-30-2020 04:36 PM

The Freud box joint set is great, but I wouldn’t use it in multiple passes to make a wider dado.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View AlanWS's profile

AlanWS

57 posts in 4335 days


#14 posted 06-30-2020 05:36 PM

I recommend the Freud blade I mentioned above for box joints, but I agree with Bilyo that an ordinary dado set works fine. If you have a problem with the way it looks, the usual approach is to not show the joint, either by cutting it stopped (more work) or by covering the edge.

-- Alan in Wisconsin

View Gene Howe's profile

Gene Howe

12186 posts in 4206 days


#15 posted 06-30-2020 05:43 PM

A decent sharpening service can eliminate those bat wings. Had that done on a set. Worked fine. But, a better option for you ma be either the Freud box joint set or Freud’s 6” Super Dado set. It produces a flat bottom wuth out the bat wings.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

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