How Accurate Should A Table Saw Cut - Router Forums
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post #1 of 39 (permalink) Old 04-16-2012, 02:20 PM Thread Starter
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Default How Accurate Should A Table Saw Cut

First of all I will be the first to admit that I am a nit-picker and have been accused of b such all of my life, so with this in mind, let me tell you what is on my mind. working with metal, accuracy to .0001" is often needed and can be achieved with the right tools and the skill of an good machinist, or so I understand, I am not a machinist but in years past I was pretty heavily involved in precision benchrest shooting and did work with tools and measurements that required being able to decern .0001" in swaging bullets and turning the necks on cartridge cases.

When I first got interested in wood working three years ago I was intrigued with Incta's fence positioning system and added it to my new table saw. The system is supposed to advance the fence in .001" incrementss using the micro adjust feature and for the most part it does, but wood is of course not as stable as is metal. I can make several cuts with the table saw with the fence locked down and the cuts will vary in length by three or four thousands of an inch one way or another from cut to cut, which is very good in almost all situations that I can imaginge for woodworking. Or so I suspect.

Using a dial caliper the variation can be decerned when reading thousandths of an inch but when the calipers are set to read in fractions, the error in the cuts is not decernable and this is with calipers that read to 1/128th of an inch which is just a quarter of 1/32". That's pretty close and closer than I have ever needed so far in the work that I have done.

I doubt that most folks reading this care much about such trivels, but they are interesting to me. The feature that I like with the system is that I can set the fence to any position that I want and and on the first cut, be right on the money. This is true if I am careful to keep the scale calibrated and I must admit that the rub comes in here. If the cut is really important, I mean really impoetant, then of course it is a good idea to make a witness cut and to check it like any one would do with any set up, so the value of the system is really up to what the individual expects and/or wants in his table saw. Like I said earlier, I am a nit-picker and like good tools, so the Incra LS Fence Positioning System turns my crank as they say. Like any tool, it is only as good as the operator.

The accuracy of the system really comes into play when cutting dovetails with the system and since I have never tried to cut dovetails with any other system, I don't know any better. It took a lot of practice to learn to cut dovetails so that I was happy with them, but practice paid off for me and the system work for me to my nit-picking satisfaction.

If anybody out there has the Incra set up and would like to compare notes, I would like visit with them about it, or if you just have questions about the system, let's talk.

Just wondering how others feel about such things.

Jerry
Colorado City, TX
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post #2 of 39 (permalink) Old 04-16-2012, 06:22 PM
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For most cutting on the table saw the accuracy read by a tape measure for the size of cut needed should be fine enough. The saw should be set to be pretty accurate when cutting multiple parts such as segments for a segmented bowl. If the cuts are off they will just compound itself when all the parts are assembled.

James
Whittier, CA.

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post #3 of 39 (permalink) Old 04-16-2012, 07:23 PM
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Jerry, accuracy to 1/10000 in wood lies somewhere between impractical and impossible. With humidity changes the dimensions can change more than that. One of the most critical jobs requiring an accurate angle is picture frames. But equally important is that opposing sides be equal in length. Our ancestors 300 years ago produced wooden works of art that we can equal but not exceed despite having tools that are light years ahead of what they had available. Apparently there is more to it than just having the best technology.

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #4 of 39 (permalink) Old 04-16-2012, 08:05 PM Thread Starter
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Charles,
i believe that I stated that the level of accuracy provided by the Incra System is greater than is normally required in woodworking, the ability to quickly do a set up and then to repeat a set up quickly is a great feature in my opinion. Maybe I am just trying to justify my purchase that I may have foolishly made in my ignorance when I got interested in woodworking and as I said, my experience with my shooting days may have influenced things too. Who knows.

Your comment about picture frames is one that I am familiar with and the Incra miter gauge with the fence and stops are extremely effective in regard to cutting the 45 degree cuts and keeping the lengths of the parts correct.

So far, the vote, only two, show no interest in the accuracy provided by the Incra System and is regarded to be a waste of money by them I think. I still like it, just wondering what other folks are thinking and i do appreciate anybody's input on the subject.

Jerry
Colorado City, TX
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post #5 of 39 (permalink) Old 04-16-2012, 08:13 PM
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Originally Posted by Jerry Bowen View Post
Charles,
i believe that I stated that the level of accuracy provided by the Incra System is greater than is normally required in woodworking, the ability to quickly do a set up and then to repeat a set up quickly is a great feature in my opinion. Maybe I am just trying to justify my purchase that I may have foolishly made in my ignorance when I got interested in woodworking and as I said, my experience with my shooting days may have influenced things too. Who knows.

Your comment about picture frames is one that I am familiar with and the Incra miter gauge with the fence and stops are extremely effective in regard to cutting the 45 degree cuts and keeping the lengths of the parts correct.

So far, the vote, only two, show no interest in the accuracy provided by the Incra System and is regarded to be a waste of money by them I think. I still like it, just wondering what other folks are thinking and i do appreciate anybody's input on the subject.

Jerry
Colorado City, TX
Hi Jerry.
Don't get me wrong. I don't think precision equipment is a waste of money at all. I will spend more money for precision. I have the Incra1000 Miter gauge & love the quality & precision it provides.

James
Whittier, CA.

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post #6 of 39 (permalink) Old 04-16-2012, 09:43 PM
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I don't think anybody on this forum will discount accuracy or precision, but having said that I also think that "nit-picking" over 1/10,000 of an inch is just that, and foolish. If you like your incra system, and it pleases you, then thats all that matters. Many of us have some expensive tools, who's to say, "that person doesn't need that level of quality"? Some of us have tools in multiples that are ridiculous, who on earth needs that many? (I am thinking of someone in particular, and it's not me, BOB ). Still, that's what they want, so go for it! Don't get me wrong, I don't mean to say that anything that makes you happy is good, just with tools. So anyways, I have 4 table saws, my wife can't figure that out, and neither can I! But I bought 'em 1 at a time when the price was right, I had 5 but sold 1 when I needed some cash. If you like your system, then you probably didn't pay too much, If you don't like it, then you probably DID pay too much! See how that works?

Jack


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post #7 of 39 (permalink) Old 04-16-2012, 11:09 PM
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Hi Jerry,

I don't have one of the nice new Icra systems but I do have the original system and fence. As you say the ability to quickly make adjustments and repeat settings with accuracy is great.

The accuracy needed to do woodworking depends a lot on what you are making. I feel the larger the piece the less accurate you have to be within reason. However I feel you should always strive to make every cut as accurately as possible, but should not get discouraged if everything is not perfect.

Some people make more mistakes if they are worrying about that small error they discovered instead of worrying about the cut they are about to make. There are things we can not control all the time like humidity, the moisture content of the wood, the internal forces within the wood that twist your workpiece as it is cut from the board you so careful squared before the cut was made, just to name a few. We can control some of these to a certain degree but not all are controllable.

I know that if you try for perfection each time you build a project you will get closer to your goal of perfection.

I hope that I never get to the point that I can look at a piece that I have created and say it is perfect because it would be real hard to live up to that accomplishment.

Wood is usually a very forgiving media to work with, and I do mean work with because it will often tell you how it needs to be tooled and it will overshadow the small imperfections you have made by displays of color and grain that can only be seen in wood.

The most important thing to remember is to enjoy the time you spend working with wood, don't spoil it if everything doesn't go just right.

Work safe, Have fun,

Mike
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post #8 of 39 (permalink) Old 04-17-2012, 07:03 AM
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Tolerance Woodworkers need tolerance from she who must be kept happy and tolerance when in the shop 1/128= .0078 1/64= .0156 and I can't measure the difference. But I use a deck of playing cards and one card is .011. This gives me a go no go less than a 64th.

In the two years since joining I have spent too much time fretting over decimals but have succesfully tuned in my TS Vega Fence within .003 with a dial guage (Also used it to tune in my benchtop planer) A thin kerf saw blade can wobble more than that. Perfection is impossible but precise repeatability is neccesary.
What set-ups and methods I use all depend on the tolerance

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post #9 of 39 (permalink) Old 04-17-2012, 07:28 AM
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I've been working with wood for 50+ years and have only use a steel rule and a drafting protractor to set up my tablesaws. As long as the blade is square to the rip fence and square to the table you're good to go. That being said, a 2" wide cut will be accurate enough even for the finest work.

Today is the first day of the rest of your life. Live it to it's fullest.

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post #10 of 39 (permalink) Old 04-17-2012, 07:44 AM
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Rather than keep harping on about how "tolerant" we should be, show us some of your "tolerably" good work, that is the measure of craftsmanship, the mark of a good craftsman is to be able to work with what they have and produce something of beauty and fineness, an article that is practical and is worthy of recommendation.

"To err is human, to foul things up totally requires a computer operated by the aforesaid"....

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