Regarding kerfs, thin and otherwise

[wreckwriter]

I see blades often described as "thin kerf". I understand what a kerf is but am not sure of the difference between thin kerf and others. I believe the riving knife is involved in making the choice but I'm not certain.

For example, I believe the stock Ryobi blade is a "thin kerf". Also the Freud LU83R010 and TK306 are described as thin kerf. The Freud LU85R010 however, doesn't mention kerf size. I was considering ordering these 3 blades from Amazon but want to be sure they'll all work for me.

Does it matter which type I use? Will there be a problem with my riving knife (currently stock, Shark ordered) if I use the LU85R010?

Thanks as always for teaching me.

Tom

[beetee3]

A regular kerf blade will work fine. Thin kerf blades have a 3/32" kerf whereas regular blades have 1/8" kerf. The 1/32" difference makes regular kerf blades stiffer resulting in less vibration. It also makes your saw's motor work a bit harder if your try to maintain the same feed rate.

[wreckwriter]

great. Thanks for the reply!

[LCHIEN]

Thin kerf means the blade tooth width is 3/32" or about .10".
regular kerf the blade teeth are 1/8th wide or .125".

Theoretically the work and thus power for the same feed rate is less for the thin kerf blade.

A properly made thin kerf blade, to me, has enough stiffness to not make vibration an issue and cut every bit as well as the regular kerf. Several high quality blade makers make thin kerf blades that sell very well, such as Freud and Forrest.

Another possible benefit is arguable, the wood wasted in making a large number of crosscuts for example, will be a good part of an inch. for most people that's not much but for some designs, an extra 1/4" of stock could save a board.

As for the riving knife, the ideal riving knife is just a skoosh thinner than the blade. There have been a number of discussions in the past about how much a skoosh is and whether a knife thin enough to use with a thin kerf blade was too thin for use with a regular kerf blade. I don't recall there ever being a consensus but I always use the same knife with both.

My opinion: I'd use a thin kerf blade any day and I'd use the same knife with either.

[JimD]

I use almost exclusive regular 1/8 kerf blades with a .090 splitter. Occasionally I use a thin kerf with the same splitter. If it is not adjusted well, I have to drop back to a thinner splitter. I think the blade grind and sharpness matter more than how thick it is. I also think the extra stiffness of a regular kerf helps it cut with about the same amount of power. For most cuts, the BT3100 has plenty of power to use either thickness blade as long as it is sharp. For deep rips, I use a ripping blade (a Freud that is 0.126 inches wide) which allows a higher rate of feed than any thin kerf blade I've tried.

Jim

[hobkirk]

Wouldn't a thin kerf blade require LESS POWER?

Using an exagerated example that seems applicable...
...and assuming equal design and sharpness of blades...

It seems a 1" wide slice would require more power than a 1/8" slice...

[I am a novice with ZERO practical experience - I was planning on using mostly thin kerf blades - I expected they might be more delicate and maybe require sharpening more often, but your answers have me re-thinking my ideas]

[lkazista]

Wouldn't a thin kerf blade require LESS POWER?

Yes, it results in the motor having to not work as hard.

[LCHIEN]

Wouldn't a thin kerf blade require LESS POWER?

Using an exagerated example that seems applicable...
...and assuming equal design and sharpness of blades...

It seems a 1" wide slice would require more power than a 1/8" slice...

[I am a novice with ZERO practical experience - I was planning on using mostly thin kerf blades - I expected they might be more delicate and maybe require sharpening more often, but your answers have me re-thinking my ideas]

Yes, I think I said that...
And its frequently advertised as an advantage.

[gimpy]

wreckwriter, my response has nothing to do with thin vs regular kerfs. It is just a heads up to remember to take into account the "kerf" when you measure a full board to make repeatable cuts. I cut a board measured to the exact width that I wanted to cut 4 identical slats from. I did not do that (take into account the kerf) and my last board cut (3rd cut) came out approximately 3/8 inches (1/8 inch for each of the three previous cut/kerfs) too narrow. It ruined my fourth board (and I did not have enough to make another cut/slat).

Sorry, just had to throw this in there.

Frank

[Knottscott]

...A properly made thin kerf blade, to me, has enough stiffness to not make vibration an issue and cut every bit as well as the regular kerf. Several high quality blade makers make thin kerf blades that sell very well, such as Freud and Forrest.

My experiences support your statement, andAmerican Woodworker also agrees....they had an excellent blade article in issue #118, Nov 2005. The newer high tech, high quality blades are plenty stiff, and give you the advantages of the TK without deflection and vibration problems. You still have to deal with 3/32" in the math equations as opposed to 1/8"

[wreckwriter]

wreckwriter, my response has nothing to do with thin vs regular kerfs. It is just a heads up to remember to take into account the "kerf" when you measure a full board to make repeatable cuts.

thanks Frank! Its a good tip.

[JimD]

Maybe it is the grind of my thin kerf blades but I do not notice that they take less power - allow a higher rate of feed. Other than the stock BT3100, I think all my thin kerf blades are ATB grind. I normally use a Freud LU84 which has 40 ATB teeth and 10 flat topped rakers. It is a bit dull at the moment (should send it off for another sharpening I suppose) so the DeWalt equivalent is on the saw at the moment. When I want to do a thick rip, I put on a dedicated 24 tooth ripping blade which allows a higher rate of feed than any thin kerf I have tried. The primary reason to reduce the rate of feed is the gullets filling up with sawdust and affecting the smoothness of the cut, you can feed pretty fast even on deep rips with the BT3100.

If the grind is the same and the sharpness the same, the thin kerf should require less power. My experience is that the grind makes more difference than the thickness of the kerf. Someday I guess I should try a combination blade like my LU84 in thin kerf (I think CMT makes one) or a 24 tooth ripping blade in thin kerf.

Jim

[Wood_workur]

My experiences support your statement, andAmerican Woodworker also agrees....they had an excellent blade article in issue #118, Nov 2005. The newer high tech, high quality blades are plenty stiff, and give you the advantages of the TK without deflection and vibration problems. You still have to deal with 3/32" in the math equations as opposed to 1/8"

I just add 1/8, to allow for a little extra wood, but if it comes down to it, I will use 3/32/

[vaking]

One statement about kerf and splitter. Splitter is supposed to be a little thinner than blade kerf. Splitter is supposed to be adjusted so the splitter edge is lined up with the edge of the blade on the side of the fence. The same setup usually works with regular or thin kerf.

[wreckwriter]

Splitter is supposed to be adjusted so the splitter edge is lined up with the edge of the blade on the side of the fence.

I didn't know this part. Thanks for the tip. I've been kicking my butt trying to get mine dead center on the blade with little success.