Table Saw Blade Deflection When Crosscutting Hardwood

[aamak]

I'm trying to crosscut 1 1/2" thick by 4 1/2" wide ash on my table saw, but I'm getting uneven cuts. The cut profile is more or less convex, with the leading and trailing edge cut deeper and the middle of the cut proud. The difference is about 0.005-0.006" on a piece that I just cut. Is this blade deflection - somthing that using a "better" blade would cure? I'm using the factory blade that came with my Steel City table saw. It's a 40 tooth carbide ATB blade. The blade is clean and looks like it is within 0.001" of spinning true at the teeth. It does appear to be cupped though. If I put my 6" engineer's sqaure on one face, I get a gap on each end. If I rock the square all the way to one side, the gap is about .008". I'm crosscutting using a home made crosscut sled that has 120 grit sandpaper glued on the face of the fence to prevent slippage. I've also tried using a small bar clamp to hold the wood in place. There is NO slippage against the fence and the sled runners are snug in the slots. The fence appears to be square to the saw blade using the engineer's square. When I cut 3/4" hardwood plywood using the same setup, the cut is just about perfect with no detectable variation. I would appreciate advice on this before I rush out to just buy a new blade. Thanks!

 

[Tarhead]

I would rule out a problem in the blade at speed and under load by using another blade. If you have a local WW buddy you could also use the SteelCity blade on their TS and see if the problem repeats. Not sure which blades they include but manufacturers are not known for spending lots of money on blades they give away. Then if the problem persists with a good blade or doesn't repeat on another TS, call SteelCity. Arbor bearing problems?:dontknow:

 

[Joe Scharle]

My Steel City (5-6 years ago) came with an excellent Leitz blade. But nevertheless, this has to be a blade problem from your description. The cupping you describe shouldn't be there. If you remove the blade and lay it on the saw top, can you still see the the 'cupping'?

Ash is pretty tough as well and the grain in a thick piece can 'guide' a blade. I've had a similar problem with thick, gnarly oak and had to make 2 cuts. First half way, second through.

Let's us know your results with another blade.

 

[aamak]

Thanks for the replies. Both sound like good info. I got back in the shop tonight for more tests. Using a magnetic base and feeler gauges, I determined that the blade appears to be lined up exactly with the miter gauge slot. Measuring against the same tooth with the blade rotated around to the front and back, it's within my abiity to measure. Measuring at teeth 180° apart from the same location on the table, there's some wobble, but it's real hard to get consistent measurements. I tried cutting again, making the cuts in two passes, without improvement. I did notice that if I make a cut with the waste side to the left, the cut is better. It also burns the wood easily on the left side of the blade, but not the right. Not sure what that means. I'm off to my friend's house tomorrow night with wood, blade, square, etc. for more tests with different saws and blades. Also, the arbor appears to be tight - I double-checked it tonight - so I don't think that's the problem. I also tried checking the blade off the arbor, but couldn't tell anything. It seemed flat. I tried measuring with the blade barely tightened in the arbor to see if it was deforming the blade, but that was inconclusive. The arbor looks ok. Thanks again!

 

[Tarhead]

Might want to grab one of these:
http://www.ncwoodworker.net/forums/showthread.php?t=38020

Great deal. Great blade.

 

[ZachEakes]

It sounds like your blade is not square to your miter slots, if it burns on one side and doesn't from the other. That is the back, or belly of the blade rubbing against the wood on one side but not the other.

I went through this dialing in my delta contractor saw, get a dial indicator and clamp it to the side of your miter gauge so you can hold it steady. Push the miter gauge over in the slot towards the blade, and hold the handle toward the blade as well to take up any back lash while you measure.

My saw didn't have enough horsepower to turn a full kerf blade, so I was trying to use a thin kerf... Cross cutting anything taller than an inch tall from the table, and narrower than the blade it would wobble in the cut the width of a pencil line.

If I lowered the blade till it was just above the height of the board, it would drift and no longer be 90 degrees or whatever angle I had it set.

I was using a thin kerf Freud blade, which is ever so slightly hollow ground...

My blade was out of square .005, with the rear bumped to the right which meant the middle of the board was chewed out by the side of the carbide teeth, until enough wood was in contact that it bent the blade the other way.

I ended up putting a larger 240v motor on with a link belt to be able to use full kerf blades and everything went happily ever after...

Zach

 

[aamak]

Update: I took some 1 3/4" thick ash and my blade to my friend's house tonight. He 1st made test cuts with his blade that were straight. We then put my Steel City blade on his Delta table saw and it made the same crowned cut and burned on the left side like it did on my saw. Then we put his Forrest blade on his saw and made another perfect cut. So, my new Freud Fusion 40T is on order from the Amazon seller linked above. I'm looking forward to checking it out when it arrives.

 

[Don Alexander]

keep in mind that the thicker the wood the less desirable a thin kerf blade becomes especially on coarse grained wood like ash and oak etc

not saying it can't work just saying that the thin kerf blade will be more susceptible to being "guided" by the grain

either way i am sure you will like the new blade

 

[aamak]

WOW!!!! I mean, the new Freud P410 blade arrived this evening. WOW!!!! I mounted it on the saw and was going to carefully check the alignment 1st, but thought, what the heck, I'll just give it a quick try. WOW!!! No vibration, crosscuts through the 1 3/4" thick Ash like it was butta. The cut is 90° and straight. One thing I noticed - right out of the box, the plate seemed thicker than my old blade. Sure enough - the plate on the Freud measures 0.100" while the plate on the old saw was 0.088". Doesn't sound like a big difference, but it feels beefy and I think it must help the stability. BTW, I bought the full 1/8" kerf blade, not the P410T thin kerf. Problem solved and thanks for all the advice. This is like Christmas in March! WOW!!!