Tear out in poplar

[tim walker]

1/4” thick stock, 1/4” wide dado, 1/2” height, Freud 8” dado blade set for 1/4” width, backer board. Why so much tear out? It also occurred in some oak and pecan same criteria, but not on every cut. Suggestion s please to prevent this tear out? Perhaps too fast feed, blades dull?

[Mel Fulks]

You can use a pocket knife to test where where cuts are smooth and quiet . Take the smooth non tear -out path, to success.

[Kevin Jenness]

Crossgrain or rip cut? Try a sharp single blade at the same setting, if you get the same results it's possible (though unlikely) the wood is funky. Otherwise, look at your dado set sharpness or tooth design. Perhaps there is some schmutz in the stack causing runout. Yellow poplar is generally easily machined with sharp tools running true.

[Carroll Courtney]

Buy few cheap(use to be cheap) plywood blades stack to thickness you need. It works, I pick up on this idea years ago while visiting a cabinet shop

[Lee Schierer]

1/4” thick stock, 1/4” wide dado, 1/2” height, Freud 8” dado blade set for 1/4” width, backer board. Why so much tear out? It also occurred in some oak and pecan same criteria, but not on every cut. Suggestion s please to prevent this tear out? Perhaps too fast feed, blades dull?

Can you post a photo of what you are seeing?

[Mel Fulks]

Cutting too slowly with dado saw can cause the wood to pinch .

[Brian Tymchak]

Can you post a photo of what you are seeing?

Also post a close up photo of the dado stack showing the tooth profile of the outer blades.

[glenn bradley]

Since you mention a backer board I assume your tear out is at the exit point. To me this would imply that the backer is not tight enough against the keeper material. Although we are all manly men, your grip alone may not be enough. Try a clamp and see if things improve. If not we can try something else but this is my first guess without a picture.

[Lee Schierer]

1/4” thick stock, 1/4” wide dado, 1/2” height, Freud 8” dado blade set for 1/4” width, backer board. Why so much tear out? It also occurred in some oak and pecan same criteria, but not on every cut. Suggestion s please to prevent this tear out? Perhaps too fast feed, blades dull?

Are you using a zero clearance throat plate with your dado setup? If not you should, because the lack of support on the bottom of the cut is a prime cause of tear out.

[Bill Dufour]

I am confused. You say 1/4" thick stock but a 1/2" deep cut. To me that is a through cut not a dado cut.
Bill D.

[Michael Burnside]

Are you using a zero clearance throat plate with your dado setup? If not you should, because the lack of support on the bottom of the cut is a prime cause of tear out.

My thoughts as well Lee. I’ve also often scored the wood beforehand with a scribe or razor blade which helps a ton in curly maple or ply.

[Kevin Jenness]

I’ve also often scored the wood beforehand with a scribe or razor blade which helps a ton in curly maple or ply.

Should not be necessary with a well-designed, sharp dado set. Posting some close-up photos of your stock, dado blades and setup would help.

[Rick Potter]

Probably off the wall but could you have placed the outside blades on the wrong sides? Some dado sets have a tiny tip on the outside cutters for clean edges.

[tim walker]

Can you post a photo of what you are seeing? Sorry, thought I posted initially 507552

[tim walker]

I am confused. You say 1/4" thick stock but a 1/2" deep cut. To me that is a through cut not a dado cut.
Bill D. I should have been more clear. The stock is 1/4" x 1". So the daddo cut is 1/2" deep. This is for partitions for a jewelry drawer.

[tim walker]

Here is how one of the drawer dividers will look. 507553 The throat plate is part of a X-Cut sled, and was used on a previous set up, so for the 1/4" cut (two large Freud blades) the current throat plate is wider than 1/4"

[Kevin Jenness]

You need a fresh backer plate behind the cut.

[Michael Burnside]

Sorry, thought I posted initially 507552

I assume this tearout is at the point of blade exit. You need a backer plate or at least blue tape to prevent that, especially on softer woods like poplar. One thing I try to do, unless I forget LOL, is all my cross grain work BEFORE final dimensioning. This lets you cut that tearout off and no need for any support or worry.

[Lee Schierer]

Sorry, thought I posted initially 507552

Tim, I went out in my shop and mounted my 8" Freud Dado outer blades on my 10" 1 Hp Craftsman TS, added a brand new zero clearance inset and made three cuts in 1" x 1/4" tulip poplar. The cuts were 1/4" wide by 1/2" tall. The wood was at 7% moisture or less.
Here is the set up:
507559507560

I made three cuts. The first cut was the 1/4" poplar with no backer in place. The second cut was the 1/4" poplar with a 1/4" backer piece. The third cut was the 1/4 " poplar with the 1/4" backer with a wrap of painters tape. Here's what the cuts looked like.
507561
The backer piece did it's job in both of the cuts where it was in place.

Here is the front piece and the backer piece showing the effects of the cut.
507562

As you can see, the cut made with no backer closely resembles what you had with your cut. The painters tape reduced the tear out but didn't eliminate it on the backer piece.

If your dado set isn't making similar quality cuts you either have it assembled wrong or your set is dull/damaged in some way. My dado set has the cutting blades marked "This Side Out" so you don't install them wrong.

When I made my egg crate for the chess set shown below, I stacked all the pieces with a backer piece and wrapped the bundle tightly with painters tape cutting all the pieces in one pass, then indexing to the next cut.
507571

[Brian Tymchak]

Yes, you need a backer board. I think most of us that use a dado stack add a sacrificial fence to our miter fence to be that backer board. I have the freud 8" adjustable dado stack. I think it's model # is 608. I'm not in my shop at the moment to confirm. I'm pretty sure that set has a flat or negative tooth hook angle which I think is to give a cleaner cut on the shoulder. It does not however help at the exit.

[tim walker]

Thanks all for the advice. I will take all in to consideration when I cut the remaining ones. Full disclosure here I did have a SawStop trigger event with the dado blade a few years ago, it did not look bad enough to replace the blade but maybe I should have.