I’ve been reading with interest about sawblades.
To be honest, Carpenters (note the capital– this is my trade) never pay much attention to their sawblades, as long as they’re sharp.
So I really don’t know that much about them, despite decades in the trade.
So I’ve been studying. (The difference between a trade and a hobby is that you can make a good living at a trade.)
Now, in the rush to thin kerf blades, I note that there doesn’t seem to be that much advantage for those of us with full-size cabinet tablesaws.
Since my saw will handle a full size, stiff, thick blade, other than a tiny bit of wood saved, what is the advantage?
I see risks, but with lots of power to drive a full sized blade, I don’t see any significant advantage.
What am I missing?
Replies
What are you missing? I guess the intended target market of think kerf blades. For those of you who have a nice powerful cabinet saw, there really isn't much of an advantage to thin kerf blades aside from the slight bit less waste and possibly faster feed rate. What I like about full kerf blades is that the kerf is pretty darn close to 1/8".
Chris @ www.flairwoodwork.spaces.live.com
(soon to be www.flairwoodworks.com)
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
This is not the blade that lives on any of my TSs, but they are good to have when you need one to make a certain piece or run work out of what you have on hand.
There is only ~ .032 difference or 1/32", but there are plenty of times that I have managed to pull an extra part out of some thick stock which had to be cut down to make a run of parts out of something on hand, saving a trip and money to the lumber yard.
Not to mention getting a faster cut with a lot less feed resistance, as long as the blade is in good shape. Once they start to dull, they will start distorting faster from heat than a normal thickness blade.
It is good to use blade stiffeners with them as well, because they are more flexible, and will tend to distort or resonate, or follow the path of least resistance quicker.
While I have some full diameter for each saw, I have come to the conclusion that it makes more sense to drop down to a smaller size, like using 8" for a 10" saw, then not use the stiffener plates. You will end up with better stiffness, and probably all of the depth of cut that you will need for most situations, at less cost, unless you find a deal, which is not unusual.
That is my 2¢
Keith,Good point on using smaller diameter blades. A while back, I needed a super thin kerf to accept a piece of plexiglas and the only blade that was thin enough (and perfect, for that matter) was my 7-1/4" circular saw blade which by the way fits my tablesaw fine. I should use it more often on my saw when I don't need to cut thick stock. The kerf is significantly narrower than even a 10" thin kerf blade. I couldn't find any specs for Freud's 7-1/4" blades, but they make a 8" thin kerf rip blade which has a 0.087" kerf.Chris @ http://www.flairwoodwork.spaces.live.com(soon to be http://www.flairwoodworks.com)
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
There's another aspect to this question which I want to toss in. Anyone who has a riving knife on his TS knows that the knife thickness must be exactly the same as the kerf - any more and it jams the cut, any less and it's useless. With standard kerf it's easy to change back and forth between different blades (ripping, cutting plywood, fine crosscut, etc) without also changing and adjusting the riving knife. So I'd wager that most anybody using thin-kerf blades does not (yet) have a riving knife on his saw.David Ring
http://www.touchwood.co.il/?lang=e&id=1
"There's another aspect to this question which I want to toss in. Anyone who has a riving knife on his TS knows that the knife thickness must be exactly the same as the kerf - any more and it jams the cut, any less and it's useless. With standard kerf it's easy to change back and forth between different blades (ripping, cutting plywood, fine crosscut, etc) without also changing and adjusting the riving knife. So I'd wager that most anybody using thin-kerf blades does not (yet) have a riving knife on his saw."
David - What we consider "standard" full kerf is typically 1/8" (0.125"), but there's considerable variability in kerf width with both full and thin kerf blades. Full kerf can be 0.118", 0.125", 0.130", 0.135, 0.145", and even 0.155". Then there are some mid kerf blads of ~ 0.110". Take a look sometime at the widths of "full" kerf blades from various manufactures....even within the same brand and series the width sometimes varies.
Yes I know. I use Dimar (Amana) blades, and they make all different kerf thicknesses. But the most common regular kerf is 3.2mm, and I switch all the time between a rip blade and a panel-cutting blade, both of which are 3.2mm.David Ring
http://www.touchwood.co.il/?lang=e&id=1
Ring,
Funny you should mention this...
I recently bought and installed a BORK bolt-on riving knife for my Grizzly saw. It's an aftermarket device that gives you, after a fashion, a riving knife on a saw that didn't originally come with one.
Unused as I am to having a riving knife, one day I unthinkingly changed out my regular, full-kerf sawblade to one of the thin kerf ones I have around my shop. Maybe I was cutting MDF or something and wanted to use a blade I didn't care about so much.
At any rate, on the first cut I noticed a shower of shiny shavings coming out from under the blade guard. The piece I was cutting, because the kerf was so narrow, had pivoted the bottom of the riving knife into the blade. Fortunately - and I know this was an intentional design feature of the BORK unit - the riving knife's blade is made of pretty soft aluminum, so nothing was really hurt. The riving knife now has a big groove milled into its bottom leading edge, but that shouldn't hurt things.
One can purchase a thinner BORK riving knife, and that's something on my list of things to do...
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
David, the riving knife thickness should be more than the saw blade plate thickness and less than the kerf. I use 3.2mm (.125") kerf blades on my Hammer sliding table saw with the standard riving knife that is 2.8mm thick. The plate thickness is 2.5mm. Felder/Hammer has 3 different riving knifes, 2.0mm, 2.4mm and 2.8mm thick. The plate thickness is marked on all the Guhdo, Tenryu and Felder blades that I use on the slider.
Kerf = 3.2mm Riving knife = 2.8mm Plate thickness = 2.5mm
http://www.dewalt.com/DWAssets/english/pdf/products/riving_knife_selection.pdf
Life is what happens to you when you're making other plans.
When your ship comes in... make sure you are not at the airport.
Edited 3/4/2009 10:09 am ET by JerryPacMan
My SC came with 2 low profile riving knives, one 3mm (I think), and one 2.5mm for thin kerf, which I've never used as it's a 3hp saw. However the tall riving knife with blade guard comes only in the 3mm size.
Jim
You're right, if you've got no power issues you're not missing anything. I've got 7.5 HP behind my tablesaw blade and wouldn't dream of using a thin-kerf.
David Ring
http://www.touchwood.co.il/?lang=e&id=1
I have to agree with Chirs. I've always found it pretty handy that a standard blade cuts a 1/8" kerf. I can't put my finger on any particular reason right at the moment, but it seems to have been useful over the years. Other than a tad faster feed, I'm having a tough time finding a good reason to spend the money on thin blades.
Verne
If a tree falls in the forest, and no one is there to cut it up and make something with it . . . what a waste!
I bought a Freud thin kerf blade for use in solid stock only. It leaves a silky cut.
The only adavantage I see is I use it on good stock only. keeping one good blade on hand. Then I swap it out for the blade that will be used for ply and MDF (when forced to use it).
To get a blade sharpened here it is a long drive.
The advantage of the TK is simply it requires less power to drive it. The disadvantage is it flexs easily in hard-wood and requires a stiffner from what I found in the days I used a 1 1/2 HP TS. And when you add the stiffener.. you lose about 1" of height capability.
I gave mine to the person that purchased my 1 1/2 HP TS when I moved up to 3 HP and then a 5 HP TS.. Haven't had one since as I run full kerf and unless someone just gave me one.. don't anticipate having one as the full is stiffer with no loss of height and as stated.. 1/8" which you can count on as various TK's have various thicknesses and not one standard.
Sarge..
There's not much incentive for someone with a 3hp saw to use thin kerf blades unless you work with considerable quantities of expensive wood where the savings makes a difference. For someone with a smaller saw trying to rip thick hardwoods, a good TK makes a big difference.
Most standard blades fall into two classifications - full kerf or thin kerf, but there are exceptions and the classifications are ill-defined. Most full kerf blades hover near 1/8" (0.125", ranging from roughly 0.118" to 0.145"), while most thin kerf blades are about 3/32" (0.094", ranging from roughly 0.090” to 0.104"). There are also some "mid kerf" blades that fall in the 0.110" range, plus or minus a bit. There are some ultra thin kerfs available from some manufacturers for special applications. Many smaller diameter blades are “UTKs”. Which kerf width to choose can be as easy as following many top manufacturer's recommendations of using thin kerf blades for saws under 3hp (ie: most compact, jobsite, contractor, or hybrid saws fall in the 1hp to 2hp range), and full kerf blades for saws with motors 3hp and up (ie: industrial cabinet saws), but that's where the simplicity ends and the debates begin. As with many choices, it'll boil down to a matter of preference and your particular situation, but I'll try to explain the logic of both philosophies.
There are legitimate arguments for both kerf widths, pro and con. To some folks, it's simply a matter of the math being simpler with a 1/8" blade than a 3/32" blade. It can also be a matter of what was available on sale at the time of purchase. Even though the width differences appear minute, a full kerf blade is typically 33% thicker than it's TK counterpart. A wider kerf blade makes a wider cut, thus taking more wood and requiring more power to make the cut at the same speed…a similar principle to a lawn mower's width of cut. There will also be a proportionately higher amount of sawdust with a full kerf blade, more wood consumed in the process, and even somewhat higher noise levels from increased wind noise (though minor). Wood savings is also a consideration, though a minor one for many hobbyists. That consideration may become more significant if you handle a lot of expensive wood. You're likely to encounter situations where a full kerf blade bogs a smaller saw more often than a TK would, most notably in thicker materials. Slowing down the feed rate can help compensate somewhat for the additional power requirements, but slower cutting means more tendency to burn the wood, and less ability to cut efficiently in thick materials.
Full kerf blades tend to be more stable than their TK counterparts due to the increased steel thickness… not much argument about the logic of the physics involved, but that's not to say that most TK's are unstable….they're not. There's a fair amount of sentiment about the stability difference between the kerf widths that I believe stems from earlier versions and poor examples of thin kerf blades, or possibly using them in situations where a full kerf blade would have clearly been a better choice. Modern alloys are vastly stronger than those from even a few years ago, and modern blade design technology has improved in leaps and bounds. Modern designs, computerized equipment, and laser cut slots combine to offer some extremely good thin kerf blades that will rival the cut quality and performance of the best full kerf blades in a home-shop type setting. While it's true that TK blades in general are more prone to flexing than full kerf blades, that doesn't mean that they're likely to encounter those issues. After years of use and testing some 30+ TK blades on a fair number of different saws, I have yet to encounter a severe deflection or vibration issue with a TK blade during a cut that was caused by the blade. A saw with acceptable arbor runout and vibration levels should be able to spin a TK blade with similar precision as a full kerf blade. Issues with TK blades are most likely to occur if a problem already exists within the saw, such as high levels of runout, in which case the TK blade will indeed amplify that problem. Wood that deviates badly from flat and straight, or thick wood with very stiff grain patterns, such as mesquite, are also more likely to cause some blade flexing, but I'll reiturate that more likely doesn't equate to likely. For most common hobby uses, a good TK blade is more than adequate, and offer some significant advantages in reduced motor strain. Commercial environments and high volume hobby environments pose a different set of challenges such as complications from large quantities, heat, and power feeders, etc. Commercial saws are almost always equipped with ample motors to spin a full kerf blade without strain are and suggested for those applications.
Now that I own a 3hp cabinet saw, there's less incentive for me to buy thin kerf blades, but when I was primarily using 1-1/2 to 2hp contractor or hybrid saws, the TK's were a very welcome commodity. With a good 24 tooth TK ripper there was nothing my smaller saws couldn't handle with relative ease, including 12/4" hard maple, QSWO, and elm. While the same saws would cut the same wood with a good 24 tooth full kerf blade, the difference in motor strain, bogging, and feed rate was noticeable. The lower feed pressure is analogous to waxing your saw's table top to reduce friction. It's not just about cutting speed, it's about ease of feeding and increased control, which is actually safer. With flat straight stock, cut quality was roughly equivalent between a high quality TK blade and a comparable high quality full kerf blade. It's difficult to discern the differences in cut quality in a reasonably controlled setting. A good TK blade won't tax a smaller motor as much as a wider blade will, especially in thick materials, and can extend the life of the motor. Ultimately the decision is yours to make, and should take into account what you cut most and what saw you have.
I agree that if you have the power, and the sharpness, the thicker blades are better. They're more stable and more predictable.
For those (including me) whose saw is 2HP or less, but who aspire to do some of the bigger projects, the thin kerf blades have a place.
As to saving wood....... not an issue unless you're running a sawmill, and then only if you are using a "gang" saw. One which cuts a large cant (a long, rectangular cross-section piece) into many boards at the same time.
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