LumberJocks

Dado tear out with brand new blades...

  • Advertise with us

« back to Designing Woodworking Projects forum

Forum topic by Ripper70 posted 09-11-2016 11:06 PM 622 views 1 time favorited 27 replies Add to Favorites Watch
View Ripper70's profile

Ripper70

183 posts in 372 days


09-11-2016 11:06 PM

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.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo


27 replies so far

View Aj2's profile

Aj2

690 posts in 1261 days


#1 posted 09-11-2016 11:15 PM

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

View MrStyle's profile

MrStyle

52 posts in 1193 days


#2 posted 09-11-2016 11:26 PM

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

View Kirk650's profile

Kirk650

293 posts in 212 days


#3 posted 09-11-2016 11:37 PM

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.

View Rick M's profile

Rick M

7913 posts in 1843 days


#4 posted 09-12-2016 12:00 AM

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.

-- http://thewoodknack.blogspot.com/

View Kazooman's profile

Kazooman

626 posts in 1416 days


#5 posted 09-12-2016 12:02 AM

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.

View nightguy's profile

nightguy

213 posts in 126 days


#6 posted 09-12-2016 12:07 AM

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.

View jbay's profile

jbay

814 posts in 362 days


#7 posted 09-12-2016 12:25 AM

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.

-- My “MO” involves Judging others, playing God, acting as LJs law enforcement, and never admitting any of my ideas could possibly be wrong or anyone else's idea could possibly be correct -- (A1Jim)

View Ripper70's profile

Ripper70

183 posts in 372 days


#8 posted 09-12-2016 01:41 AM

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.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

View jbay's profile

jbay

814 posts in 362 days


#9 posted 09-12-2016 01:49 AM

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.

-- My “MO” involves Judging others, playing God, acting as LJs law enforcement, and never admitting any of my ideas could possibly be wrong or anyone else's idea could possibly be correct -- (A1Jim)

View TheFridge's profile

TheFridge

5765 posts in 949 days


#10 posted 09-12-2016 02:02 AM

A new zci will work wonders. So will scoring.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View ArtMann's profile

ArtMann

136 posts in 279 days


#11 posted 09-12-2016 03:54 AM

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?

View ArtMann's profile

ArtMann

136 posts in 279 days


#12 posted 09-12-2016 04:00 AM

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.

View Ripper70's profile

Ripper70

183 posts in 372 days


#13 posted 09-12-2016 04:08 AM



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.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

View nightguy's profile

nightguy

213 posts in 126 days


#14 posted 09-12-2016 04:23 AM

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.

View Rick M's profile

Rick M

7913 posts in 1843 days


#15 posted 09-12-2016 05:05 AM

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.

-- http://thewoodknack.blogspot.com/

showing 1 through 15 of 27 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com