That is fine but if the precice calibration only corrects 10% of the problem you need to learn how to make compensations to remedy the problem.
AND going back to my original points to the OP, dial calipers are good for measuring and setting up equipment. The results of using that equipment is not guaranteed to give good results when using wood as the material to construct with.
All of them if you can compensate, but for instance a precicely calibrated saw will not eleminate tear out on the back side of a cut. There are other factors to consider to minimise the tear out. Excessive tear out can ruine a joint and technique can certainly minimize tear out. For instance when cutting a 45 degree miter on your TS if you have the miter gauge clocked to
45 in a particular direction it prioduces a better/cleaner cut than if you clock the gauge to 45 degreesin in the opposite direction. This all falls into technique and no amout of precision will make both setting equal in results on a consistant basis.
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.
It sparked a spirited discussion; however, it clearly defines a few things.
In the data acquisition business, if you truly want an accurate measurement, you make a differential measurement, not a single ended one.
Single ended measurements introduce instrument as well as people errors into the measurement, something differential measurements eliminate because they cancel out.
Using ANY measuring instrument to make a measurement is a single ended measurement.
Ask 5 people to make a measurement with a micrometer of vernier caliper, and chances are pretty good you will get 5 different answers.
Set up a table saw, cut a piece, then break the set up.
Now reset the fence to the same dimension, cut a 2nd piece and compare it with the first.
They will be close, but they will be different.
I submit your fingers are the best instrument for this measurement.
Biggest reason I know for "sizing" all the material for a job using a single setting for the tool (Planer, table saw, etc) as the first step in processing the wood.
BTW, you also do it all at the same time.
Weather conditions tomorrow will be different than today.
" snipped-for-privacy@aol.com" wrote in news: snipped-for-privacy@a70g2000hsh.googlegroups.com:
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...
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.
DCH wrote in news:Xns9A8AE3AAA90E3hayniedcgmailcom@
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.
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.
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.
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