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Thin Kerf or Thick Kerf?

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Forum topic by DavidNJ posted 577 days ago 1786 views 0 times favorited 19 replies Add to Favorites Watch
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DavidNJ

384 posts in 619 days


577 days ago

I’m currently using a Diablo 90T Hi-ATB for crosscutting, plywood, MDF and a Diablo 24T ATB for ripping stuff 1/2” and over on a very old Skil 3400 Type 2 benchtop table saw. It actually works, the blade is square to the miter slot and fence. The table is tiny.

My wife is VERY insistent that I get a SawStop. I cut my finger trying to change a blade to day (see my other thread on where to get an arbor wrench: Where Can an Arbor Wrench Be Purchased?). That will end up being the 3hp PCS model. Realistically, the earliest I’d have the saw ready is late February. I expect this to be a relatively long term purchase, so I’d like to make a good choice.

In the meantime I’d like to get flat tooth 24T ripping blade and a 40T general purpose blade (Infinity Super General or Freud Premium Fusion. While a thin kerf would better on the old, little, Skil, would it also be better on the 3hp SawStop? From reading knotscott’s blog (Tips for picking a saw blade) I’m still undecided.

Both Infinity and Freud offer their 24T and 40T Hi-ATB blades in both full kerf (.125 for each on the 24 T, Freud .118 on the 40T) and thin kerf (.091 for Freud, .097 for Infinity).

Which should I get realizing it will spend its life on the 3hp SawStop?


19 replies so far

View knotscott's profile

knotscott

5417 posts in 2001 days


#1 posted 577 days ago

A good 3/32” thin kerf blade should still work with a 3hp SawStop, provided the blade is at least as wide as the riving knife, but there’s a lot less incentive to use them with a 3hp saw because it’ll spin a 1/8” full kerf blade with ease. If buying new blades, I’d opt for full kerf if you don’t use a lot of expensive exotic wood.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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DavidNJ

384 posts in 619 days


#2 posted 577 days ago

Even on the 24T ripping blade and 40T general purpose?

View JesseTutt's profile

JesseTutt

802 posts in 736 days


#3 posted 577 days ago

Many years ago when I purchased my table saw I asked the same question and was told that there was less flex/wobble/side-to-side distortion on a full 1/8” width blade and therefore you get a smoother edge. Until recently I followed this advice. Now I own a 3/32” thin kerf blade and don’t see any problem with the cut edge. Although I have not tried the thin kerf in 8/4 wood.

-- Jesse, Saint Louis, Missouri

View DavidNJ's profile

DavidNJ

384 posts in 619 days


#4 posted 577 days ago

If stability was an issue wouldn’t a stabilizer help? One advantage is the reduction in fine wood dust from the smaller kerf. One difference between commercial shops and home shops is the quality of the dust collection, both volume of air moved and the effectiveness of the hoods. Reducing the sawdust, especially fine sawdust, should help.

The cost difference is insignificant. With both brands the 24T and 40T blades are available with a thin kerf; with Infinity the 80T is only available with a full kerf. For 110v saws, knotscott recommended the thin kerf for ripping but the wide kerf for crosscutting.

View Loren's profile

Loren

7390 posts in 2273 days


#5 posted 577 days ago

With 3hp and more powerful cabinet saws, full kerf
blades deliver nicer cuts. Thin kerf has two major
advantages: in 115v saws it allows for faster cuts,
less burning in tough stock and a feeling that
the saw is more powerful. It also wastes less
wood when cutting thin parts. If that is a real
concern I suggest finding a way to use the
band saw.

Blade stabilizers help but may limit depth of cut.

-- http://lawoodworking.com

View pintodeluxe's profile

pintodeluxe

3318 posts in 1439 days


#6 posted 577 days ago

On a 3hp saw it may not matter much. On my 1.75 hp saw, I could not rip 8/4 oak like I do with my thin kerf Freud 24 tooth. No burning, no stalling – just cutting.
The cut quality is very similar. My full kerf 50 tooth combination blade gives glass smooth cuts, but will often burn thicker stock. My thin kerf ripping blade leaves minute swirl marks that you won’t see or feel until you hold it up to a raking light. The swirl marks come out easily with normal sanding.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View DavidNJ's profile

DavidNJ

384 posts in 619 days


#7 posted 577 days ago

Is there any back to back comparison test? Same blade in different kerf, same stock. Crosscut and rip.

Note: the Wood Magazine article of 40T combination blades tested the Freud Premium Fusion and Infinity Super General in full kerf, but didn’t test them in thin kerf!!! They fought to a virtual draw but it looked like the Freud may have an ever so slight advantage.

View SamuraiSaw's profile

SamuraiSaw

447 posts in 590 days


#8 posted 577 days ago

The thin kerf blades will be advantageous on lighter duty saws, but in my experience can be problematic on heavier saws. I have a PM2000 and have given away all but 1 of thin kerf blades. Thick stock tends to induce wobble with the thin kerf while the full kerf remains stable. I have no proof, but I suspect full kerf blades will also allow for more and better sharpenings.

-- Artisan Woodworks of Texas.... www.awwtx.com

View Rick  Dennington's profile

Rick Dennington

3307 posts in 1820 days


#9 posted 577 days ago

I say “Both”.....’nuff said…...........!!!!!!!!!!!!!!!!!!

-- " I started with nothing, and I've still got most of it left".......

View knotscott's profile

knotscott

5417 posts in 2001 days


#10 posted 577 days ago

I’ve tested both kerfs on a few occasions. If the saw is set up well, the stock is flat and straight, and you use a good quality blade, the TK will perform nearly on par with the full kerf the vast majority of the time…..high quality is an important factor in that statement, and it doesn’t apply to cheaply made blades. It isn’t until lateral forces like the stiff grain found on mesquite or warped boards, or excessive heat that the TK’s will would be likely to pose an issue. Full kerf is better for high volume and long duration cutting sessions where the blade doesn’t cool much between cuts. The nature of the thinner plate makes TK’s more prone to flutter….it doesn’t mean they “will” flutter, but they’re more prone to when stressed. A stabilizer shouldn’t be necessary if the saw spins true, and they often mask other underlying issues. When I had saws with motors under 2hp, the TK’s were a realblessing…they were always easier to feed, and cuts were excellent, but there’s simply less incentive to accept the potential drawbacks with a 3hp saw….the motor won’t work hard, and your feed rate will be nearly as fast as you dictate even with full kerf.

A good TK blade should be fine if that’s what you want so long as the splitter isn’t wider than the kerf of the blade, but the major benefit of being easier to spin is pretty much a moot point with a 3hp saw. Wood savings are marginal for low volume operations unless you’re using very expensive wood. It is true that TK’s produce less saw dust, and lower noise too, but aside from that I don’t see much advantage in favor of the TK for your circumstances.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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DavidNJ

384 posts in 619 days


#11 posted 577 days ago

Wouldn’t the stiffener help in the case were the thin kerf plate wasn’t stiff enough? Wouldn’t the teflon coating help reduce the temperatures? The full kerf plate is about 20%-25% thicker with proportionally greater heat capacitance.

This is Freud’s graph of the temperature performance of their coatings. I believe Infinity’s “Nickel Armor” coating is equivalent to the Freud Silver I.C.E.

View hokieman's profile

hokieman

163 posts in 2379 days


#12 posted 576 days ago

I agree with Loren. If you have a 3 hp motor go regular kerf. You won’t get as much blade wobble whereas that is a downside to a thin kerf blade. Thin kerf is for smaller motors,

View DavidNJ's profile

DavidNJ

384 posts in 619 days


#13 posted 575 days ago

Do you know anyone who has blade wobble with a thin kerf blade? I understand the theory, but is their any empirical evidence?

If there was blade wobble, wouldn’t a stiffener/stabilizer correct that?

View knotscott's profile

knotscott

5417 posts in 2001 days


#14 posted 575 days ago

Yes, of course, maybe….it depends on the cause of the blade wobble. If the saw’s arbor spins true, and the wood is flat and straight, you shouldn’t need a stabilizer. If the saw vibrates a bit, and triggers the blade to oscillate, a stabilizer might help a little, but it won’t cure the cause of the vibration. If the blade follows the path of least resistance in a line of stiff grained wood, a stabilizer should reduce the tendency of the blade to follow it to some degree. If the blade heats up and loses it’s tension, it can wiggle like a wavy potato chip, and the stabilizer won’t do much for that.

You’ve asked for opinions on TK vs FK, and have gotten many responses….the overwhelming majority are suggesting full kerf for your saw, yet you continue to restate, rehash, and re-ask many of the same questions. What do you want to hear to be satisfied? What are you looking to gain with the thin kerf? Will your splitter/riving knife allow a thin kerf to pass without binding? There are pros and cons for both. If you want to get thin kerf, get thin kerf…it’ll cut wood.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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DavidNJ

384 posts in 619 days


#15 posted 575 days ago

knotscott, I’m trying to separate old wives tales from actual issues. Most of us have opinions based on what we have been told rather than what we have observed. We rarely ask for empirical evidence to support what we’ve been told. Your posts are highly valued because you have actual experience supporting your views.

The thin kerf always produces less sawdust. It appears that the finishes on the higher quality blades all manage heat build up. In the one item you listed that wasn’t a saw defect—the blade follows the path of least resistance in a line of stiff grained wood—you indicated a stabilizer would reduce or eliminate the problem. Even so, if the grain was that stiff, is the 22%-to-38% range difference in plate thickness enough to overcome the issue?

It would seem that full kerf blades became a standard because of their approximately 1/8” width rather than an engineering analysis of the dynamics of the blade. The thin kerf seems to be a response to lower powered saws. As a result, some of the better blades only come in full kerf models. However, the two listed above—24T FTG and 40T Hi-ATB—come both full and thin.

The SawStop riving knife is .071 so shouldn’t be an issue; for comparison the Shark Guard riving knife for thin kerf is .091.

In the Wood Magazine retest, which is somewhat questionable, there were two blades that were the same model in full and thin kerfs: the Forrest and the Ridge Carbide. They were very close between full and thin.

Scott, have you been able to test the same blade in thin and full kerf back-to-back?

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