Reply by knotscott

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Posted on Tablesaw Blade 101

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8056 posts in 3401 days

#1 posted 12-27-2009 11:02 PM

It’s not necessary to use a negative hook on a straight miter saw, but is highly recommended for a sliding miter saw or a RAS.

Like many things, kerf width is a matter of choice, with pros and cons each way. Your saw and what you cut most should really be considerations in that decision though.

From my blog on blades:
”...Which kerf width to choose can be as easy as following 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. To some folks, it’s just a matter of the math being simpler with a 1/8” blade than a 3/32” blade. It can also be a matter of not knowing any better, or what was available on sale at the time of purchase. Both kerf widths will work with most saws, but note that changing kerf width can skew the zero reference on the measuring tape of a left tilt saw, so you’ll need to address that if you change kerf widths. Even though the width differences appear very small, 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. Wood savings can be a consideration, though a minor one for most 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 easily 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 of a tendency to burn the wood, and less ability to cut efficiently in thick materials. Your splitter or riving knife width should also be part of the consideration. Choosing a blade that’s thinner than the splitter blade can cause the board to stop mid cut if the board binds on the splitter.

Full kerf blades tend to be more stable than their TK counterparts due to the increased steel thickness and body mass…there’s not much argument about the logic of the physics involved, but that’s far from saying 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 computer aided designs, computerized equipment, and complex laser cut slots can 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 using and testing dozens of TK blades on a fair number of saws, I have yet to encounter a severe deflection or vibration issue during a routine cut with a TK blade that was caused by the blade itself. 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 emphasize that “more” likely doesn’t mean “likely”. It typically requires substantial lateral pressure to cause a blade to deflect. For most common hobby uses, a good TK blade is more than adequate, and offers some significant advantages in reduced motor strain and lower feed pressure. 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 and are 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. 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 easily 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 safer. With flat straight stock, cut quality is 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, which is additional evidence of the equality between the two kerf widths. A good TK blade can extend the life of a smaller motor by posing less strain. Ultimately the decision is yours to make, and should take into account what you cut most and what saw you have.

Many blade manufacturers recommend the use of blade stabilizers, dampeners, or stiffeners with their blades. Especially with thin kerf blades, but many make the same recommendation for full kerf blades too. From a technical perspective, it’s more right than wrong to make that recommendation. Not much harm in the recommendation, and there’s some possible benefit for both buyer and seller, so why not? First off, be aware that you give up some cutting height capacity with a disk installed. The larger the diameter of the stiffener, the less height capacity that’s available. Secondly, my experience has been that there’s no noticeable difference with or without them when using good blades on a good saw. A high quality modern blade mounted on a properly running table saw while cutting flat straight stock shouldn’t need stabilizers. I’ve read far more responses on internet forums that agreed with my view than opposed it, but as always, there are some exceptions. I vote to save your money and take your spouse (or “significant other”) or lunch with the money saved. If it turns out that you’ve got a runout problem with your blade, then by all means, get yourself a stabilizer to help, but note that it’s usually a $20 band-aid for another problem, and not a cure….”

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

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