is the table saw blade sharp?

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Old 02-11-07, 02:00 PM
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Question is the table saw blade sharp?

Quick noob question:

how can you tell if a blade needs sharpening?

The background:
I just obtained a used table saw, and it has a carbide tipped blade and although it cuts well enough for me (small home shop) I don't really know the indications of when the saw should be sharpened.

I suppose one sign would be whether the wood being cut starts to splinter. But is there anything about the shape of the teeth that would indicate a need of sharpening?

Should the face of the teeth be flat? or should they have a curve?

Thanks!
 
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Old 02-11-07, 02:33 PM
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Most carbide tips are flat, cut at a slight angle. I know what you mean by not knowing when to change the blade. Blades can cost upwards to $70 each for 12" 100 tooth ones. So after buying a few, I keep a rack of them and have them resharpened when I feel they are bogging down. (Speaking of which, I have to do that tomorrow). I can have them resharpened for $10, so until they can't be resharpened any more, I use them.
If the blades burn the wood, or you have to put excessive pressure on it in order to obtain a cut, it is dull. A sharp blade will cut you, while a dull one will hurt you.
 
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Old 02-11-07, 03:06 PM
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A good question. Chandler pretty much answered it when he mentioned "feel". You can usually tell if a blade needs sharpening by the speed at which it cuts, the quality of the cut, and the effort it takes to feed material through the blade.

Much to my chagrin, I must admit that I am a bad one when it comes to keeping my general construction blades sharpened. When ripping material, you can tell the blade is dull when you have to force the wood through it using muscle. Sometimes the blade will bend, wobble or audibly "ring" as it passes through the wood. The cut may be rough or uneven. When ripping some items, that doesn't matter. But when doing finish work, you definately want a sharp blade.

So when I do switch blades to do finish quality work, you can really tell the difference. The blade cuts effortlessly- biting through the wood without any muscle at all. The cuts are straight and clean, with no vibration or wobble at all. You only hear the smooth sound of the saw motor- not additional noise that comes from blade vibration. And most of all the speed of the cut is noticably faster, which you can hear by the speed & sound of the motor. A miter saw with a sharp finish blade, for instance, will cut through oak like a hot knife through butter. A dull blade will noisily hack its way through in twice the time. -makes me wonder why I don't change blades more often! Lazy and cheap, I guess.

I'll probably catch some flack about using dull blades, but what can I say. After using an old dull one, putting on a new, sharp blade sure makes you appreciate it a lot more.
 
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Old 02-11-07, 03:56 PM
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With a newly-acquired saw, you really should tune up the machine before worrying about sharpness of blade teeth. Imagine cutting with a perfectly sharp, bent, handsaw. Yeah, it cuts better than the dull, bent, handsaw.

I currently use a large 18 amp saw. It was formerly owned by a retired professional cabinetmaker. Yet, I found the guts of it put together indifferently, so machine geometry was way out of true and good cuts were impossible. Now I've got the beast tuned like a musical instrument and it cuts sweet and true even with relatively dull blades.

I know partially reverse engineering a tablesaw seems daunting, but IMO this is worthwhile if only to gain better understanding of how the machine works. If you know the saw intimately, you'll know when it's perfectly tuned.

I strongly recommend you at least skim a few books covering tablesaw setup and calibration. My favorite publisher is Taunton Press (Fine Woodworking Magazine); favorite authority is Kelly Mehler - a real tablesaw guru/geek. He did a few books and videos for Taunton, you can check out from the library.
 
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Old 02-11-07, 04:12 PM
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table saw setup

Thanks for all your replies!

Yes, I just bought a book by Mehler: http://www.amazon.com/Table-Saw-Book-Completely-Revised/dp/1561584266

I'm still learning my saw and I think it's pretty good to go, but the more I read, the more I learn.

Based on your responses, I'd say I need to sharpen the blade. The face of each tooth is curved, as if someone took a round tube file and filed away material. Also, the cuts that I have made with it weren't effortless to say the least.

After I soak the blade in some citrus degreaser, I'll see if I can't find a sharpener pro. Now, if I can just find my yellow pages.

thanks again!
 
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Old 02-11-07, 07:46 PM
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Then why do we continually cut thousands of board feet of lumber with the same blades, or until we wake up and change the blades???!! I don't know, but like XSleeper says, we just don't. But when we do, we are so pleased with the smooth cut.
 
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Old 02-14-07, 05:35 PM
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It's a time delay for sharpening

Originally Posted by chandler View Post
Then why do we continually cut thousands of board feet of lumber with the same blades, or until we wake up and change the blades???!! I don't know, but like XSleeper says, we just don't. But when we do, we are so pleased with the smooth cut.

I know why people don't sharpen their blades more:

#1 minimum 1 week turnaround. I drove about 12 miles to the other side of seattle to find a place that would do it within a week. Most places have a pick up and drop off time of monday--if you drop it off on tuesday, the blade won't get picked up until NEXT monday, and returned the monday after that. That's ridiculous!

#2 Cost, although cheaper than buying a new blade, by far, I'm still paying 50 bucks to have mine sharpened, but that also includes about 4 replacement teeth at $4 bucks a tooth. (80 tooth blade is about 25 bucks to sharpen)

What kind of machines are used to sharpen these blades, anyway? I found this post indicating you can do it by hand: http://www.askmehelpdesk.com/tools-power-equipment/how-do-sharpen-table-saw-blade-5743.html
 
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