# Dado tear out with brand new blades...



## Ripper70 (Nov 30, 2015)

Hey All,

I finally got myself a set of dado blades for a project I'm working on. I opted for the Oshlun 8" SDS-0842 after reading some positive reviews here and elsewhere. They seem like a well made set and I used them for the first time today.

I'm using a dado joint on some 3/4" birch plywood for a table saw station I'm building. I used a piece of scrap "B" grade material to make a test cut and make sure I had the proper fit. The blades seemed to cut quite nicely. Picture of the resulting cut below:










I then ran my 3/4" birch stock through and got a much different result. See below:



















So, is it just me or the wood or did I do something terribly wrong here? Thankfully, this will be the inside of the cabinet and it's just a garage project but I'd like to know how to avoid this in the future. Any and all advice would be greatly appreciated.


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## Unknowncraftsman (Jun 23, 2013)

It doesn't look like good Birch plywood to me.But I don't use plywood very often the stuff I buy comes in a 5×5 sheet.
Try making a scoring cut first one that barely cuts the thin veneer.
A zero clearance insert is a must.

Good luck

Aj


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## MrStyle (Aug 30, 2013)

I agree with Aj2 it appears that if you use a zero clearance insert your problems would be solved.


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## Kirk650 (May 8, 2016)

I had a similar problem, so I made a zero clearance insert from thin plywood. Slowly raised the dado blade up through it, and it works great.


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## wormil (Nov 19, 2011)

Compare thickness of the top plys. The birch veneer looks paper thin while the pine might be thicker and resisting tear out better. Usually a scoring cut would be done by running the wood backwards over the blade just peeking above the insert, but a zero clearance insert should help a lot. If it still tears out then you'll have to score it with knife prior to cutting or put tape over it.


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## Kazooman (Jan 20, 2013)

Have to agree on both points. A zero clearance insert would be great. Easy to make using your original insert as a template to create a piece that just fits the saw and then you raise the dado stack to just go through the insert. However, the "Birch" stock may well be faced with a veneer of birch, but it is not real "birch" plywood. Your picture shows a massively thick layer of the ply just below the surface veneer layer, That is not a quality plywood.

The solution to your problem. Make a zero clearance insert for your dado stack at the exact width you need , AND buy some better plywood.


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## nightguy (Aug 2, 2016)

Looks like some cheap BBS Birch Ply that I had, top layer is supper thin, and inferior glue in my estimation. The ZC insert would be a big help or try some Masking tape where the cut is going to be.


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## 000 (Dec 9, 2015)

Crappy Plywood. 
A zero clearance insert will help but it won't stop it. 
Your going to have to raise the dado blade about 1/32 and score/precut it, 
then raise the blade to your final depth and make the finished dado.
Please Don't run your wood backwards through the blade, saws aren't made for that your asking for trouble.


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## Ripper70 (Nov 30, 2015)

Thanks for all the replies.

The ZC insert was something I thought about up until the point that my test cut came out so cleanly. Then, when it did, I didn't want to take the time in that moment to make the insert so I just went ahead and carried on. It'll be first on my list of things to do tomorrow.

As for the birch ply, I didn't even consider that tear out would be an issue as I had already broke the 8' x 4' panels down with my circular saw and cut to dimension on the table saw without any tear out issues. It wasn't until I used the dado stack that I had the problem.

I checked the invoice form the lumber supplier and what I bought is listed as *4' x 8' Birch Plywood #2* and I paid $48.95 for the sheet. Should I have gotten something different? Did I get ripped off? I'm still a bit in the dark about all the different grades and classifications of wood and making my way through the maze when ordering from the yard is still a mystery to me.

For my next dado I will use the scoring technique as per your advice along with the ZCI. But I have some other projects that I'm considering using a nice veneered plywood for so I want to be able to get a handle on this before moving on to what's next.

Thanks again for the help.


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## 000 (Dec 9, 2015)

If it still doesn't work, I've gone as far as making 2 saw cuts the width of the dado then dadoing out the middle.
Funky process, but when you need a clean edge, sometimes you have to do what you have to do.


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## TheFridge (May 1, 2014)

A new zci will work wonders. So will scoring.


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## ArtMann (Mar 1, 2016)

That looks like the results you get using plywood from Lowes or Home Depot rather than real imported Baltic Birch plywood. The veneer is extremely thin and doesn't appear to be very well glued to the substrate. Are you sure the material is good?


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## ArtMann (Mar 1, 2016)

There is a big difference between real Baltic Birch plywood imported from Europe and the domestic stuff you get at big box stores like Home Depot or Lowes. All that I have ever seen is 5 feet square, although some may be imported with different dimensions. The material looks to be of poor quality to me. The veneer is very thin and doesn't appear to be laminated to the substrate very well.


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## Ripper70 (Nov 30, 2015)

> That looks like the results you get using plywood from Lowes or Home Depot rather than real imported Baltic Birch plywood. The veneer is extremely thin and doesn t appear to be very well glued to the substrate. Are you sure the material is good?
> 
> - ArtMann


Well, no. I don't think it's Baltic Birch Ply. It's my (limited) understanding that BB Plywood comes in 5' x 5' sheets and is of the highest quality. This was labeled as "Birch Plywood #2" came in 4' x 8' sheets and cost me ~$50 for the 3/4" panel. That's why I asked in my earlier post if I got a raw deal or if this was to be expected from this grade of plywood. What do you think?

I'd have been upset had this been purchased for an important cabinet or something more meaningful. FWIW, it did cut well with my other saws using Freud blades. It wasn't until I used the dado that I even noticed how thin the veneer was.


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## nightguy (Aug 2, 2016)

Here is WI at Menards, Lowes or Home Depot I have never seen Baltic Birch, just Birch Ply, and it looks like the stuff posted here, the layer is so then, with the brown adhesive underneath it, the top woods almost grayish.


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## wormil (Nov 19, 2011)

Baltic Birch ply is expensive and I've only ever known it to be sold by lumber dealers that sell to cabinet shops. Big box stores sell hardwood plywoods that are poplar cored with a thin veneer face, they come in birch, maple, and oak, possibly walnut. Around here they run $45-48 for a 4×8 sheet 19mm thick. There is also seen a cheaper variety that is $39 and identified as "sanded plywood"; I believe it has pine cores and a hardwood veneer face. The difference is easy to tell, baltic birch will have many even layers and looks like a better quality plywood. Hardwood plywood will have fewer layers, typically a greenish tint to the inner cores, and a paper thin veneer on top.


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## Unknowncraftsman (Jun 23, 2013)

Try some BB plywood next time it's so much better.
Life is too short to work with junky material.
I know you were making something for your saw station.So I say go ahead and treat yourself it's just a few dollars more.
If your out here in So Cali you find it at Cherokee lumber.
Good luck

Aj


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## rwe2156 (May 7, 2014)

Yes its cheap plywood but that looks like an excessive amt of tear out to me.

Check the outer blades. Sometimes there is an inside or outside to the tooth set.

I don't use a ZCI for dados because you would need __ (filll in the blank) for each width. Instead, I use a high quality dado set and if I need an absolute clean cut in ply, I pre-score with a marking knife.

Rick M is right with the exception that lumber dealers also sell the cheap China stuff so you need to specify you want the $72/sheet stuff, not the $40 :-D


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## Ripper70 (Nov 30, 2015)

Well, it may be cheapo plywood but, at $50 bucks a sheet, it ain't exactly cheap!

The blades are labeled for correct orientation so I'm sure I had them set correctly.

I'll try the scoring method as your point of needing a separate ZCI in each one of the various sizes was something I hadn't thought about. The veneered panel itself actually looks pretty nice. I'll experiment a bit to see how it holds a stain and finish but for any indoor projects I'll bite the bullet and get the more expensive wood.

This wood did come from a lumber yard but I guess they source from the same place that HD gets their stuff. I specifically avoided HD because I couldn't for the life of me find a decent panel or a straight plank in the entire store. I figured the yard would have better quality stuff (which it did) but it's still lacking somewhat.


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## pintodeluxe (Sep 12, 2010)

I don't think my dado blades would make a cut that rough in a 4×4, let alone finish ply. The better dado sets will cut pretty cleanly in any material. 1+ on the ZCI, but I never have to make scoring cuts with my Freud or Infinity dado sets.

Are you sure the outer blades aren't reversed? There is a left and a right blade, and they can be accidentally swapped (teeth will still be facing forward). I can't tell from your picture, but it would be worth checking.

The first time I installed a dado blade, I actually put it on backwards… the whole set with the teeth backwards. To my surprise, it still cut, but not very well.

Good luck, I hope there are some small changes you can make to get better performance from your dado blade.


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## Ripper70 (Nov 30, 2015)

The blades are clearly marked "This Side Out" on the outer blades and I made sure to orient them correctly (only after putting them on incorrectly when I first got started).

The more I look at the tear out on the birch panel the more it's becoming clear that the veneer is so ultra thin that a scoring cut and a ZCI are in order if I expect to get a clean cut. I'll try to incorporate both of these extra steps and see what happens. Hopefully I can get better results. Results that more closely match the cut that I got on the scrap piece.


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## Ripper70 (Nov 30, 2015)

Results are demonstrably better after taking the advice of fellow L'Jockers. In the interest of time (as in having very little of it) I decided to try the scoring method and forego the ZCI for the time being.

First, the tiniest scoring cut just through the veneer:










Then the full 5/16" dado:










Much better results! Count me as among the happy customers with the performance of the Oshlun dado set. Not bad for paying less than $90.00 bucks on Amazon.com.


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## 000 (Dec 9, 2015)

With the grain the cut should be better anyway. Did you try any cutting against the grain?


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## Ripper70 (Nov 30, 2015)

> With the grain the cut should be better anyway. Did you try any cutting against the grain?
> 
> - jbay


I hadn't thought of that. But if you look at the first picture you'll see that it was cut against the grain and that was without a scoring cut on a B grade plywood. Perfectly clean.


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## Tony_S (Dec 16, 2009)

Your main problem isn't your dado blade or the lack of a zci(although a zci would 'help')....it's just crap import plywood. Plain and simple.
Also, comparing a cross grain cut vs. a long grain cut is apples and oranges(especially with crap plywood).
As is comparing cuts in a domestic softwood ply(first pic) with a hardwood veneered ply, grades aside.

You also mentioned that you used Freud blades previously when breaking down the material with no issues. Again, comparing any good quality combination blade to a dado blade is apples to oranges.

You can see in the third pic how far the veneer is torn away from the glue layer underneath. The veneer wasn't glued properly to the core ply's.
Your second last pic…..pink glue. I've only ever seen import plywood with pink glue….and look at the layer glued to it. It's badly torn out as well(revealing the pink glue).


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## Ripper70 (Nov 30, 2015)

> As is comparing cuts in a domestic softwood ply(first pic) with a hardwood veneered ply, grades aside.
> 
> - Tony_S


Interesting observations. How can you tell that the softwood ply is a domestic variety? The invoice labeled it P.T.S. Plywood and charged me $36.95 for a 4' x 8' sheet. It was fine for constructing shop cabinets but wouldn't make for a very attractive armoire.

So, if the lumber yard is going to charge ~$50 for crappy plywood, what other alternatives are there that would strike a happy balance between quality and price?


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## Cooler (Feb 3, 2016)

I have two sets of dado blades (both from Freud). The first set I bought for my table saw and it will tear out like yours.

The second set I got for my radial arm saw and it has a negative hook angle and it does much, much better.

If you need perfectly clean cuts, then get some 3/16" thick hardboard and using carpet tape laminate it to the surface. Then cut your dados.

Strictly speaking I think the grooves in plywood, particle board, etc are "grooves" and not dados. I was taught that dados was the term for cross cut wood grooves only. But that distinction seems to be in the past nowadays.

But you will hear me refer to "grooves" when others are calling it "dados".

The hardboard will absolutely do the job, but it is an expensive way to do this.

I was able to minimize the tear out by making four or four cuts for the groove. The first cut was just deep enough to go through the first layer of plywood. The second went through the second layer only, and the third went through the third layer only. By then there was enough thickness to prevent the tearout. The issue was that you could end up with enlarged grooves from the repeated passes.

I think that the negative hook angle dado set is a better answer. I use the postive hook angle for utility stuff and MDF or particle board.


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## Tony_S (Dec 16, 2009)

> Interesting observations. How can you tell that the softwood ply is a domestic variety? The invoice labeled it P.T.S. Plywood and charged me $36.95 for a 4 x 8 sheet. It was fine for constructing shop cabinets but wouldn t make for a very attractive armoire.


Pure assumption truthfully…..
In the Canadian market, to the best of my knowledge, import softwood ply is pretty much nonexistent. I've had thousands of lifts come through the shop over the years, all made in Canada. Mainly due to heavy tariffs If I remember correctly. 
The US of A….I shouldn't assume so quickly. During a conversation I had with a supplier a few years ago, he mentioned that the US did import a small amount of softwood ply from South America, but the #'s were small because it wasn't recognized by any of the North American Standards counsels. All softwood ply should be rated as 'structural'(Hardwood ply doesn't have to be) in North America. It wasn't, so home builders(main market) couldn't use it. This MAY have changed over the last few years.
PTS means 'plugged and touch sanded' btw…..just a grade of softwood ply.



> So, if the lumber yard is going to charge ~$50 for crappy plywood, what other alternatives are there that would strike a happy balance between quality and price?
> - Ripper70


To be completely honest with you….there isn't a happy balance imo. Hardwood plywood is a bitch, plain and simple.
Best I can offer you is to shop around and find a vendor who offers a good quality, domestic grade at a decent price, and stick with them. Ask questions, If you find a product you like, find out what mill it comes from. You might be able to shop it around. Also don't be lulled by the word 'domestic' either. There's no shortage of ******************** domestic plywood around either.


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