Dado batwings

[RickS]

I'm planning on a Dado set for my 3HP CS; performance is more important than price.

At least some of the manufacturers produce the outside blades such that they score the workpiece to achieve perfect edges and avoid tear-out. While this is nice, the scoring is bound to also leave a small valley at the bottom corners of the dado (some have called these batwings).

I am hopeful of using the dado set to also cut box joints and various shouldered joints (lap, tenons, rabbets, etc) that may require multiple passes over the blade to achieve full width. Having the blade score the joint at the edges of each pass would seem less than desirable.

Since some of these joints may be visible in a finished piece, are the batwings also visible?

Of the sets listed below, which are more or less better in this regard?

Forrest Dado King, ~$270. Claim: most well known as the best. Outer blades score workpiece. (Does this leave visible ridges?)

Freud SD508, ~$200 Claim: contends as the best. Square Tooth, and Chip-Free. (No scoring?)

Freud SD608, ~$250 Claim: same as 508, but replaces shims with patented dial.

Ridge Carbide Dado-Master, ~170. Claim: perfect flat bottom. Compare against best known set for $100 less.

TIA,

/rick, who owns a Forrest WWII, and is very pleased, and has been leaning toward the Forrest Dado King but for the potential batwing problem.

[Phillip Hallam-Baker]

As far as I can tell all the dado sets have batwings, the Woodworker set does as well.

But I have spoken to a guy who uses one frequently enough to have needed to get the set resharpened and he said that the woodworker people were happy to take the batwings off for him.

Give them a call, this is a pretty common issue.

The other tip the guy had was that for most people there was no need to buy anything bigger than a 6" dado and the smaller amount of mass moving arround can cut the chance of kickback somewhat (no idea if he is right but it can't hurt).

I have the Freud set, it is pretty good, I plan to use a router and the Incra jig for box joints. I would not want to be fiddling with shims, the dial head is a big time saver.

[David]

There is approximately .004" of scoring. It's visible when you use multiple passes to widen a dado when looking into the slot, but if you are concerned about what shows at the end of the work piece, it's pretty darn insignificant. I just got a brand new sd-508. I called the mfg. and they confirmed that the .004 is necessary for chip free edges, which are IMHO, VERY important. The chip-free claim is true. Melamine will have ZERO chip out. I was really surprised at how good it can leave the edges of melamine.

I can't tell you anything about the others.

David

RickS wrote:

[U-CDK_CHARLES\Charles]

Most of the time, it doesn't matter. What I'd do in your case is do some test cuts and see whether or not it's noticable in your application.

If you decide it REALLY matters, then you might want to consider using a router instead of a dado.

For now, I'm using a router because I don't own a dado, but there've been Many times where it would have made things easier.

[Joe Wilding]

I have found that those batwings (I would personally call them batman ears, but anyway) tend to disappear once you have you joint glued up.

[RickS]

In the diagrams I have seen, I frankly viewed them as Batman ears too, but since others had coined a term, I thought it best to stick with the common nomenclature.

I have not seen a closeup _photo_, let alone a live example, of these dado cuts, so I am unclear as to how pronounced these batwings really are.

Since most everyone cries the praises on any of the dado sets I mentioned, I doubted the issue was significant, but still worth some investigation before dropping the cash these products command.

Your reply is what I was hoping for (and expecting).

But Phillip's reply still leaves me with pause. If not significant or noticeable, why would anyone want to -- and in the case of Forrest, agree to -- alter the blade's design to remove the cause of these batwings?

/rick.

"Joe Wilding" replied...

[Edwin Pawlowski]

I have this one and it does a great job. I've never seen any problem with wings. If it was not so damned cold out there in the shop I'd cut a dado and send it to you.

Keep in mind, they offer a 90 day 100% satisfaction guarantee.

[RickS]

Well, it's the thought that counts, Edwin... thanks. Even here, down in S. Florida, it is so cold my Oak insert has siezed in the shriveling table saw iron.

/rick, who has read good comments about the Ridge Carbide set, appreciates your additional endorsement, and might be swaying in that direction.

[J]

Forrest will grind the blade anyway you like. They do it because you pay them.

-j