How close is close enough...

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Sorry... you are right. I simply took it for granted that one wold assume that if you take the time to build a jig, you would build one to the best of your abilities OR requirements. To me, a jig should work to tolerances that satisfy one's own needs. To me that was a given for any experienced craft person, but you have made a good point about taking things for granted. So to simplify, I believe you should build a jig to tolerances that do the job they are designed to do as good as possible, but with the thought of repeatability foremost in mind.

It was a global statement that was obviously another avenue of confusion. I should have said, "I don't understand why someone would use a table saw to perform an operation that is better performed by a purpose designed and built machine that is task specific for one operation".
Having tried to cut 21/2" crown on a table saw, it sent me running back to my miter saw. I needed stain grade work, and I was unable to see how to cut one degree, or a half degree off with the table saw to close a hair line crack in a joint. OK, some clarification here: it wasn't on a shop built cabinet. It was in a house, where every ceiling corner is a square as the framers framed it, and the tape and float guys finished it. Each small piece of a corner may have to be cut several times to get the right angle to compliment the out of square corner.
You are obviously a proud defender of the table saw, and looking at your site (good work, BTW) it is easy to see how important that tool is to you. BUT FOR ME.... if there is a better tool for the job, I am all over it. My carpentry jobs rely on speed and accuracy. I am to start a crown molding job in a house in a couple of weeks. I won't be taking my table saw to do the cuts. Sadly, I have a tendency to go with the tool that does the job the most accurately with the least fuss.
If you are comfortable with you saw, wooden jigs and calibration equipment, why not?

I see where this is headed. And if you believe that a wood jig can take the daily rigors of use as well as a purpose built metal jig, all I can say is "good for you".
Since I rely on my tools for my living, I like metal guides, rails, beds, ways, and metal on metal adjustments. I am tasked with working on site 99% of the time, and my tools are loaded and unloaded day after day. Just the movement knocks them out of ajdustment sometimes. If I worked in the closed environment of a shop and had all manner of tools on hand like the TSA Jr, dial gauges, extended reach calipers, etc., at my finger tips, I just might feel differently.
As with me, you are certainly welcome to your opinion.
YM obviously varies...
Robert
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wrote in message

soooooo....do you guys think a variation of way less than 1\128 compounded over five eight inch cuts would be close enought for a dude in his garage trying to make some nifty things for his house and freinds?
This sure is better than all the spam we been gettin as of late...
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"DCH" wrote:

Let The Flying Red Horse be your guide.<G>
Lew
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LMAO...
No kidding!
Robert
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Probably not if you are making segmented pieces or pentagons. Although, if they were compound cuts and all oriented the same at the time they were cut, and assembled with the same orientation I'd bet no one would notice.
Seriously, it just depends on what you are making. I would suggest you just try you jig out, and if you like the results, all the rest is just baloney.
Robert
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216.77.188.18:

Going back to physics measurements, if your uncertainty (variation in the cut in this case) is 1/128, then 5 cuts would give you a total uncertainty of 5/128, or just over 1/32". That's +/- 5/128, too, so some cuts could be more and some could be less.
One hidden truth is that some cuts will be a little less and some will be a little more... You'll wind up somewhere in the middle of your uncertainty range, not at the edge cases.
Puckdropper
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You can only do so much with caulk, cardboard, and duct tape.

To email me directly, send a message to puckdropper (at) fastmail.fm
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On Apr 25, 2:56 am, Puckdropper <puckdropper(at)yahoo(dot)com> wrote:

Exactly. And a great explanation, too. It illustrates well when it is time to do something rather than to contunue to fiddle over the last RCH.
And of course the optimum results would be that the cuts would somehow be arranged (or cut) in a way that compliment each other making the difference almost non existent.
Robert
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Are ya'll sure thats not backwards....the variance over 5 cuts is less than 1/128 not 1/128 over one cut....
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Puckdropper is right on. Try it yourself. Unless you try to orient your cut pieces so that the variances align as complimentary angles, they will compound themselves.
But just as importantly, the other issues that are raised here come into play. That is technique, repeatability of the underlying equipment, materials, etc.
Robert
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Why correct error so small that it does not factor? Very often climate changes totally negate all accurate measurements. One day your loose parts to a drawer fit fine, the following day the fit is too lose or too thight. With years of experience you learn to compensate and work with mother nature. Precice measuring tools are fine to use for a start but the results are often out of phase with climate changes and your technique.

Keep in mind that neither is a constant, one element is constantly changing which pretty much over rides the results/effect of a particular setting.

Calibration is important but results with any given calibration often change with the climate and your technique. It's not a labratory invironment where you can calibrate "everything" with materials that are a constant shape and size.
Experience counts for a lot in the results you get.

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Did you see any constants in my equation? That's why they are called variables NOT constants. (See equation).

True. Eliminate the error you have control over by doing a precise calibration at the beginning.

True. But this is extremely relative.

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Well hopefuly your equipment is more of a constant and can be depended on for repeated settings with out using an externam measuring device.
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Depends on the project. What's the maximum width?
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