Tool Review - Incra TS-III Tablesaw Fence
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There are two distinctly different theories when it comes to tablesaw fence design. The first theory says that you should build an extremely tough fence, set it on a couple of rails, and beat on it until its accurate. This is the Beisemyer approach. Now, I'm not knocking Beisemeyer, quite the contrary. They make a very accurate and durable (almost bullet proof) fence. The second fence design theory says that you should build a lightweight fence and attach it to an extremely accurate measuring mechanism. This is the Incra approach.
The Incra TS-III tablesaw fence is built of lightweight (but very rigid) aluminum. The fence system consists of two rails (one for the front of the saw, one for the back), a rip fence, a measuring arm, a bridge, and a locking mechanism. To understand these parts, take a look at the first picture below from the Incta on-line products catalog. The fence rides on the front and back rails and is locked in position by way of the measuring arm and the locking mechanism that rests on the bridge. The arm has a slot for an adjustable measuring tape which passes by an indicator on the locking mechanism. The locking mechanism has a rack of teeth that automatically align the fence with a measurement accurate to .002". The locking mechanism also has a fine adjustment knob that is advertised to be accurate to .001", but in practice is infinitely accurate depending on how fine your touch is. This is an oversimplified explaination of how the fence works. It is designed to work with many accessories that Incra offers to act as a router jointery system as well as a tablesaw fence. For the purposes of this review, I'm treating it strictly as a tablesaw fence.
The TS-III is very accurate and it provides good repeatability, but in practice, it has a few problems. The first thing that I noticed is that, depending on the weather and the amount of dust floating around in your shop, the locking mechanism has a tendency not to release when the locking lever is disengaged. The second problem that I noticed is also weather related. If you live in an area that experiences high humidity, wooden (MDF or particle board) table saw extensions WILL NOT stay flat. Both the shop-built extensions and the store-bought extension have warped a bit. Ordinarily, this wouldn't be a big deal, but when properly set, the Incra fence slides within a about 1/32" above the table top. If your extensions happen to warp upward (as they almost always do) the fence will drag on the table. The third problem (this is the one that really bugs me) is that, when pressure is applied to the fence during a ripping operation, the fence has a tendency to flex and twist on its center point were it attaches to the measurement arm. This is just the nature of aluminum. There is a thumbscrew on the front end of the fence that lets you lock the fence in position on the front rail and that seems to fix the problem. But, all of the speed gained by using the locking mechanism is lost because you have to loosen and retighten the thumbscrew every time that you move the fence. The forth problem (This one is pretty anoying too) is considered by Incra to be a feature. The length of the measuring arm allows you a 32" cut. If you pony up for the optional 7' rails, you have to remove the bridge from the rails and move it further away from the blade to use the additional length of cut. You also have to move the bridge if you want to use the fence on the left side of the fence or if you want to use the fence with a drop-in router table insert in the left table extension. According to Incra, moving the bridge should take less than 10 seconds, but I know from experience that is very rarely that smooth of an operation. And, once you've moved the bridge from its original location, the measuring arm's built-in measuring tape is worthless because the measurement is correct only when the bridge is 32" to the right of the blade. But I digress...
Overall, I like the idea of the Incra TS-III. Its true that the fence is very accurate and very repeatable. But how much accuracy do you really need anyway? Paul and I tend to disagree on this subject. The Incra system appeals to Paul's nature. He likes things to be as accurate as possible. I'm more of a "close enough" kind of guy. That is not to say that I don't make accurate measurements, but when working with wood, a material that has the ability to move in any direction a 1/32" over night, I don't think that .001" accuracy is necessary. As I said in the first paragraph, there are two theories on tablesaw fence design, those that you have to beat on in order for them to be accurate and those that are accurate by design. The difference between the two, in my mind, is that when a Biesemeyer-style fence is off by 1/32", you beat on it until its right. If you beat on the Incra fence, it will never be accurate again. The Incra TS-III is a nice system, but if you're going to use it alot, be prepared to pull your hair out a little.
My advise is that if your saw comes with a Biesemeyer (or a Biesemeyer clone), use it in good health. But, if having .001" accuracy is important to you, give the Incra TS-III a try. Whatever you decide, take both fence styles for a test drive before buying. Its time well spent. The Incra TS-III 32" system is available at www.woodpeck.com for around $400. By the way, a Biesemeyer of comparable size costs around $300 and you can pick up a biesemeyer clone for around $200.
Incra TS-III
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Paul's Incra TS-III
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Biesemeyer Fence
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