Saw Blade is Harming my Baltic Birch

[Kent Adams]

Ok here's the crime scene:


Baltic Birch 1/2"
Rip Cut, side facing the table is getting these carbide marks throughout the rip line
Saw Blade is a Forrest 10" Duriline Hi-A/T 80 tooth blade $$$$ Not a thin kerf http://www.forrestblades.com/10-duraline-hi-a-t-saw-blade-80-teeth.html
TS is a 5 hp Powermatic, perfectly square fence, level etc.


Cross cuts are beautiful, both sides, no tear out. The underside of the rip though is horrible on the veneer. Is this a problem with my technique (perhaps too fast of a feed rate), my blade, my saw, voodoo curse ????

First picture is the top cut line, the 2nd picture is the bottom cut line and what you see extends throughout the 5 feet of cut.

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[Leo Graywacz]

It's baltic birch. It's chippy. And at times the grain is flaky.

[Kent Adams]

But I was told this was the best plywood for cabinets :(. I think something else is going on here. Why would the top cut be perfect but the bottom cut line be jagged like this?

[Leo Graywacz]

Because the sawblade is coming down on the face of the plywood and has the support of the plywood itself. The underside of the plywood has no such protection and as the sawblade exits the cut it can pull the grain with it. This is why expensive saws have a scoring blade. It's main purpose is to prevent tearout on the backside of the sheet good.

Making a zero clearance insert may help. Having a sharp blade with many teeth can help. Having a blade with an alternate bevel and a low rake angle can help. Other techniques like pre-scoring the back side can help. Lower the blade so it's only 1/16" up and make the cut. Then raise the blade and make the same cut. You should have very good results this way. It is time consuming.

Plywood quality has a lot to do with it. Blade quality and machine precision also have a large bearing on it. But bottom line is the backside of plywood will chip out without a scoring attachment.

[Kent Adams]

Plywood quality has a lot to do with it. Blade quality and machine precision also have a large bearing on it. But bottom line is the backside of plywood will chip out without a scoring attachment.

I'm not sure a better blade than I'm using exists on the market and I've not had these results using Borg birch plywood. However, I did have the blade at a different height this time than I usually do so I'll try to rip one with the blade lower.

[Mike Schuch]

Not all baltic birch is created the same. Some cut better some worse. You can try a zero clearance insert. Some times raising the blade so the cutting force is directed in a more downwards direction helps... sometimes not. You can try pre-scoring the cut with a utility knife. I think the best way to eliminate tearout is to use a table saw with a scoring blade... but that is a very expensive option!

[Leo Graywacz]

The lower the blade the better results you should have. It's always a balancing act. If you go to low then you'll get chipout on the topside of the material.

[Kent Adams]

Because the sawblade is coming down on the face of the plywood and has the support of the plywood itself. The underside of the plywood has no such protection and as the sawblade exits the cut it can pull the grain with it. This is why expensive saws have a scoring blade. It's main purpose is to prevent tearout on the backside of the sheet good.

Making a zero clearance insert may help. Having a sharp blade with many teeth can help. Having a blade with an alternate bevel and a low rake angle can help. Other techniques like pre-scoring the back side can help. Lower the blade so it's only 1/16" up and make the cut. Then raise the blade and make the same cut. You should have very good results this way. It is time consuming.

Plywood quality has a lot to do with it. Blade quality and machine precision also have a large bearing on it. But bottom line is the backside of plywood will chip out without a scoring attachment.

Ok, I solved it. Here is what I did:

1. Made a cut without a zero clearance but lower the blade to about 1/8" above the stock. Nearly no teeth marks on the underside.
2. Switched out to a zero clearance, kept the saw blade 1/8" above the stock and this time PERFECT!

Conclusion: Technique was the issue. I had the blade too high which caused deflection in the blade at high speeds because there was no support via the stock thickness or by a ZCI. Lowering the blade to match the stock helped to nearly eliminate deflection. Lowering the blade and adding the ZCI eliminated the deflection and resulted in a perfect cut, top and bottom.

[Leo Graywacz]

And you thought it was the plywood....silly you...:D

[Brian Tymchak]

Ok, I solved it. Here is what I did:

1. Made a cut without a zero clearance but lower the blade to about 1/8" above the stock. Nearly no teeth marks on the underside.
2. Switched out to a zero clearance, kept the saw blade 1/8" above the stock and this time PERFECT!

Conclusion: Technique was the issue. I had the blade too high which caused deflection in the blade at high speeds because there was no support via the stock thickness or by a ZCI. Lowering the blade to match the stock helped to nearly eliminate deflection. Lowering the blade and adding the ZCI eliminated the deflection and resulted in a perfect cut, top and bottom.

Excellent! Just a quick comment. You are running a 1/8" blade. I doubt it was deflecting, or at least enough to cause any issue with cut quality. Lowering the blade changes the angle at which the teeth come through the back of the bottom layer of veneer. Instead of coming straight down on it (with the blade set very high), with the blade set lower the angle through that veneer acts more as a slicing action. So, lowering the blade took better advantage of the design of the blade. And a ZCI always helps since it supports that bottom layer of veneer.

[Joe Bradshaw]

Kent, in situations like this, blue painters tape is your friend. Put a strip on the down side of your plywood on the cut line. Instant zero clearance.
Joe

[lowell holmes]

Not all baltic birch is created the same. Some cut better some worse. You can try a zero clearance insert. Some times raising the blade so the cutting force is directed in a more downwards direction helps... sometimes not. You can try pre-scoring the cut with a utility knife. I think the best way to eliminate tearout is to use a table saw with a scoring blade... but that is a very expensive option!
Technique is important, but Mike nailed it. There is some crummy baltic birch out there. I don't buy it at the borg, I go to Houston Hardwoods or Clarke Hardwood Lumber Co.

Find one near you.

[Leo Graywacz]

Kent, in situations like this, blue painters tape is your friend. Put a strip on the down side of your plywood on the cut line. Instant zero clearance.
Joe

I do this all the time for crosscuts. I do a lot of toekick cutouts and it helps quit a bit. To the point of no tearout. Good addition.

[David Nelson1]

Scoring all 4 sides with a panel gauge, marking gauge, or suitable knife and straight edge with cut the fibers and unless you miss the mark it actually has no chance of tearing out.

[Kent Adams]

This isn't Borg birch, this is true BB. The problem turned out to be my technique.

[Terry Wawro]

Kent, in situations like this, blue painters tape is your friend. Put a strip on the down side of your plywood on the cut line. Instant zero clearance.
Joe


This works great. I do it all the time. I'm currently cutting down some kitchen base cabinets to fit in a laundry room. Nice clean edges with no tear out.

[Peter Quinn]

We've been climb cutting rift white oak for a while, scoring blade is broken on the slider. I raise the blade a light 1/16", go backward across the blade, raise the blade just about 1/2 a tooth above the plywood, then make the cut going forward....nearly perfect edges on both sides. Digital power lift makes this easier. We recently got a new FS Tool super high ATB melamine blade for the slider, scoring is pretty much not necessary with this blade, I'm pretty impressed..keep in mind its a bigger blade than a cabinet saw so the exit angle is more gentle at any given blade height.

On a cabinet saw you already solved the problem, lower the blade, ZCI is a big help, keep the fresh as they do wear out. I've also climb cut plywood on the cabinet saw alone with the blade just barely above the plate, safety police will issue a ticket, but its fairly easy and harmless with the blade that low. I only do that where absolutely necessary.

[Gerry Grzadzinski]

I've also climb cut plywood on the cabinet saw alone with the blade just barely above the plate, safety police will issue a ticket, but its fairly easy and harmless with the blade that low. I only do that where absolutely necessary.


There's no need to climb cut with the blade that low. You'll never get any chipping or tearout cutting 1/16" deep.