rlitman
Well-known member
First, the Smile link shows me MY own Smile charity choices, not yours, so I think that's where some of this confusion comes from.
Second, nice blade choice. That one may very well be my next chop saw blade (though my current DeWalt is still pretty sharp).
Here's what I think. Blade vibration and wobble lead to rough cuts, and you can actually hear when a blade is vibrating.
Thin kerf blades are necessarily more flexible and prone to wobble, but you can still use them and get good results.
There are several primary causes of blade deflection and vibration. As macgee pointed out, over-driving the blade is a big one, and it's the most easily preventable. Here, I'll add something. It's the teeth that power the wobble. ATB teeth cut alternately on each side, so as each tooth makes contact, the blade is alternately driven left and right (the forces on an ATB cut are always imbalanced, kind of like how a 2-flute endmill is in a slot). The stiffness of the blade plate limits how far each tooth pushes it side to side (since a thicker plate has a higher spring constant), but the energy put into the vibrational system is damped by the springs that are laser cut into the blade. This is why I pretty much exclusively use laser cut blades. Those weird wiggly cuts in the middle of the plate that don't look like they do anything actually absorb and dissipate the kinetic energy that the teeth put in, minimizing vibration. You can easily hear the difference, and the reduced sound means reduced wobble too.
So, from this, it makes sense that less force on the teeth means less energy input to wobble. But that force could be coming from the motor turning the blade, or from you pushing the stock. So, when you need to force the stock into the blade to feed (which is what happens with a full kerf blade on a benchtop saw), you induce the same wobble that you'd get from running lots of motor power into a fast moving cut.
There's a sweet spot here where everything balances out, and that's why thin kerf blades are preferred with lower power benchtop saws, and full kerf on high powered cabinet saws.
But there's more. Rip blades (TCG is a modified rip pattern) don't have nearly as much imbalanced forces, because they have plane shaped teeth without significant skew. So, especially for benchtop saws, there's no advantage to going with a full kerf rip blade.
Then, there's tension and differential temperature. Most people don't realize this, but (good) blade plates are much more than just a stamped piece of steel. They're actually stretched and shrunk through hammering to set tension in the middle, in much the same way that bicycle spokes maintain tension on the rim. This is the primary force that keeps the blade flat. Well, as you cut, the outer edge heats up first, which causes it to thermally expand. If it doesn't have room to expand into, it warps into a wavy mess that wobbles, killing cut quality. The solution to this are those weird question marks you see that extend from a handful of gullets around the blade. They're expansion slots, and they're important if you're doing repetitive cuts.
It depends on your saw. My cabinet saw has a 3" arbor pulley. That rises to just under the table, so if I were to use 4" stiffeners, they'd cut into my maximum cut depth.
If your saw is direct drive, you cannot lift the blade as high, so maybe a 4" would work? You'd need to measure to be sure. You can lift the blade as high as it will go, and mark it at table height. Don't forget to account for the thickness of your zero clearance insert.
