Kerfs

[Matt P]

I don't understand something about table saw blades: If a full-kerf blade is 1/8" and a thin-kerf blade is 3/32", that's only 1/32 difference - is that enough to matter at all?

[Jamie Buxton]

That's a reasonable question. Others may have different opinions, but I find there is a difference. Thin-kerf blades tend to flap around more than regular-kerf. That is, if you look at the surface left by the blade, the thin-kerf blade sometimes leaves deeper scores.

[Ed Peters]

constitutes a 25% reduction in the amount of material being removed. This also diminishes the amount of "REAL" (not peak generated) required to power the blade. Not so much a concern on cabinet saws probably but bench top and portables need to conserve wherever they can.

Ed

[scott spencer]

It seems like this discussion has been popping up alot lately. Since there are fans of both types, I chalk it up to a matter of preference which type you prefer. There are however some matters of physics to consider. I don't think the 1/32" is enough to amount to any significant wood savings, but 1/8" compared to 3/32" equates to a 25% increase in kerf width. TK's are theoretically more prone to flutter, but the vast majority of modern high quality TK's will not in a hobby setting....commercial environments are likely to be "more hostile". Assuming a good TK with no flutter, they require less power to make the same cut because they take less material. If you've got 3 hp cabinet saw, there's less incentive to consider a TK because lack of power isn't likely to be concern, but anything smaller will struggle more to cut 2" stock, so the TK's can make a notable difference.

FWIW, I've tried around 25 good TK blades (http://sawmillcreek.org/showthread.php?t=61724&highlight=blade+turns) (along with a dozen or so full kerfs), and have never encountered noticeable deflection, but I have noticed an easier feedrate in every case comparatively. The feedrate differences in most 3/4" material using a general purpose blade doesn't amount to a big difference, but as you get into thicker materials, the feedrate is quite noticeable, which poses less strain on the motor. Once you approach much over 6/4", the task is better suited for a rip blade where the feedrate differences are easily noticeable, The TK's require less pushing, which feels safer to me...its similar to the feel of waxing the table....there's just less resistance. In my experience, the cut quality has been comparable if you stay with high quality blades.

It's worth noting that I typically use stock that's been milled flat and straight...it's possible that ripping wood that twists and bows may be more likely to deflect a TK blade than a full kerf. Also, a TK may amplify excessive arbor runout, so if you've got an arbor that doesn't run true, a TK may be more problematic. The lesser TK's are more likely to contribute to deflection/flutter/vibration problems, but they're not always the cause.

American Woodworkers issue #118 had an excellent blade article that reinforces the benefits of a good TK blade in smaller saws. They also noted comparable cut quality.

HTH,
Scott

[Hunter Wallace]

I like that the FK blades are a nice even 1/8"...
I get confused working at 32's:p

[Jim Becker]

When you consider what the "area" of all the teeth add up to, what might seem insignificant on a single tooth gets to be more meaning full. That said, I'd personally stick with a 1/8" kerf blade even on a contractor's style saw outside of a special need. It's just easier to standardize, IMHO. And Hunter brings up another good point...mental math is a lot easier at an eighth!

[Don Bullock]

Those of us who have saws with a riving knife a TK blade is not an option since the riving knife is 1/8' thick.

[James Phillips]

Those of us who have saws with a riving knife a TK blade is not an option since the riving knife is 1/8' thick.


Don I may be wrong (I use full kerf), but I think the SS riving knife will work with a thin kerf. I think it is just under 1/8" and it has a tapered leading edge. This would allow the kerf to open slightly around the RK and pass. I so not think you would notice any resistance and the kerf would not be able to close on the balde so the RK would have done its job

[Scott Whiting]

Don I may be wrong (I use full kerf), but I think the SS riving knife will work with a thin kerf. I think it is just under 1/8" and it has a tapered leading edge. This would allow the kerf to open slightly around the RK and pass. I so not think you would notice any resistance and the kerf would not be able to close on the balde so the RK would have done its job
I haven't used the SS myself but I know when I got my Biesemeyer removable splitter it was an early one and I had to sand it down to .095 to make it usable with a full kerf blade. A riving knife is more precisely aligned but I still would shy away from the extra force needed to open up the kerf after the material passed through the blade.

[Bill Huber]

I have a very under powered saw, it is only 3/4 HP.

I use a thin blade a lot and there is a difference in day light and dark. I have a Forest I and love the blade but I can sure tell the difference in the way I can feed the wood.

I have also noticed that with the thin blades I will sometimes get a cut that is not straight all the way though. That is it will have a slight dish to the cut.

[glenn bradley]

The numbers are small but the percentage is 25%. If your driveway was 25% narrower, would you notice while pulling in? :D Also, kerfs are "generally about" 1/8" and 3/32". There is a wider array of widths "around" those FK and TK designations. Tooth shape, number of sharpenings, plate thickness, etc. all contribute. I have no problems with TK blades on a correctly adjusted saw and it does put less stress on the motor.

[Jim Becker]

Glenn brings up a good point...not every "full kerf" blade is exactly 1/8" (.125) This isn't generally a major problem, but it can mean re-adjusting your fence as you switch blades if they are not "close" in width and for folks who use a scoring blade, etc., it can be frustrating. I try to buy blades that are matched in kerf width if I can...

[Jerry Lawrence]

I use thin kerf blades in an industrial setting and I can sum up the reasoning in one word: "savings". Yes, it uses less power to cut with a thinner blade, but that's not my issue. As far as rougher or inaccurate cuts, I cut 2" thick exotic wood stock anywhere between 1/4" down to paper thin pieces all for laminations, and glue them right off the saw, so pretty straight and smooth off the blade. When I say "savings" I'm talking about that extra 1/32" of wood I'm saving and the money that represents. Here's some quick 'mental math' to back that up: The laminations I make consist of between 90-100 individual pieces of 2" material, (1/4"-paper thin), all 48" long. The wood I use is generally padauk, wenge, pao amarillo, purple heart, zebra, figured maple and some others. For easy math lets say the laminations contain 96 strips. If I save 1/32" of wood on each strip, that's 3" of width, 2" thick by 48" long and you have 2 board feet of wood saved for each lamination set up. I make one of these about every 2 weeks. Let's say my average per foot price for wood is $15.00, that's $30.00 saved every two weeks or $780 per year. I've been doing this for 14 years now. $780 X 14 = $10,920 saved (all approximate of course). That's a couple of pretty nice new toys over the years. Good enough reason for me to go thin kerf! :)

[Matt P]

I see what you mean Jerry. Do you have pics of your work? If you have any tips on how to cut thin strips on the table saw safely.. (I'm a newbie)


:)

[scott spencer]

I use thin kerf blades in an industrial setting and I can sum up the reasoning in one word: "savings". ... Let's say my average per foot price for wood is $15.00, that's $30.00 saved every two weeks or $780 per year. I've been doing this for 14 years now. $780 X 14 = $10,920 saved (all approximate of course). That's a couple of pretty nice new toys over the years. Good enough reason for me to go thin kerf! :)


...I don't think the 1/32" is enough to amount to any significant wood savings, but ...

One year's savings would be enough for me to stand corrected, or at least rephrase my statement! :D $10K is a nice chunk of change! Ever experiment with ultra thin kerfs? (1/16")

[David Epperson]

I cut 2" thick exotic wood stock anywhere between 1/4" down to paper thin pieces all for laminations, and glue them right off the saw, so pretty straight and smooth off the blade.
I'm wondering why you don't use a bandsaw for these. Or is just due to surface finish straight off the saw?

My issue is also to reduce waste more than any power requirement, or rather to remove as little as possible so that reglued pieces come closer to matching grain when reassembled (cutting tops off of boxes, removing cup to flatten wide boards by slitting, etc.) But for this I'm working up a small saw that will use the 6" dia 1/16" kerf blades used on the cordless circular saws..