Precision Framing Square?

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I'm working on a project, and have determined that both of my framing squares aren't square. I have a precison machinists square I checked them against, and the 24" one is close, but the 12" one is way off. As a guess, the 24" one is out of square by more than 1/32" of an inch, and the 12" is off by half again or twice that much.
I need something bigger than the machinists square for woodworking, but I certainly can't rely on the old fashion stamped steel ones from Home Despot.
Suggestions?
Thanks!
Doug White
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Tune up what you have...
This site gives the basic directions.
http://zo-d.com/stuff/how-do-i/how-to-check-and-adjust-a-framing-square.html
John
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I've heard of this approach, and the large square is probably close enough to give it a shot. I suspect I'd have to beat the hell out of the smaller square to get is closr to right.
I'll report back on how it goes. I can probably use my machinists square to get started. It's not clear how precisely I can draw and check the lines, but over the long leg, I should be able to get pretty close. I may also start by stoning out any nicks & dings, and then I can use a precision straight edge for the "base" of the alignment test.
Doug White
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The nicks and dings are a clue that they've probably been dropped a time or two... generally the root cause of the problem. If you do the math you'll find that a small movement at the corner will make pretty significant changes at the ends of the legs--the corrections will most likely be in minutes not degrees. As such you may not have as big a beating to undertake as it might seem at first!
John
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On 3/14/2010 12:32 PM, Doug White wrote:

It may help if you mention what it is that you are making that takes that kind of "squaring" precision out of a framing square that is normally good for the proverbial "1/8th in 8" on a good day (not including pitch, rise and run, rafter layouts, etc, ot course.)?
When a competent carpenter/framer needs more of such precision over a distance than inherent in a "framing square", he uses math.
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This is for cabinet making, of a sort. I have an aluminum frame that I am fitting shelves to, and the frame is eminently square. It's made from 80/20 structural aluminum (http://www.8020.net /).
My ShopSmith table saw is a wonderful tool, but the miter gauge is the weakest part of the system. Cutting 14" wide shelves resulted in errors close to a 16th of an inch. (Yes, I know, I should make a sled). I wasn't surprised, and had planned on straightening things up with my router. I checked the shelves initially with a general purpose combination square. To set up a guide for the router, I grabbed my smaller framing square, which showed that the shelves weren't nearly as out of whack as I first measured. That's when I discovered that no two of the four wood working squares I tried agreed. I went to my machine shop and got out my "serious square" and found errors of one sort or another in all of them. The worst is the smaller framing square.
Doug White
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Been there. Done that. It works. Warren
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On 3/14/2010 10:12 AM, Doug White wrote:

I bought a Lee Valley's stainless carpenter's square a couple of years back and was delighted to discover that (as far as I've been able to determine) it's dead-on square. I use it to square up my CNC router.
Almost as good: there's not a speck of rust on it. :)
--
Morris Dovey
DeSoto Solar
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Doug White wrote:

Get this one from Harbor Freight; http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber41
It may not be any more square than the ones you've got, but at least it's readable!
The stamped steel squares you mentioned are difficult to read after a few years. This one has a yellow enameled surface with brown numbers on its face.
The HF model even has a set of numbers called "centimeters" which, I think, have something to do with the quantity of different fruits that will fit in a standard peck.
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On 3/14/10 10:58 AM, HeyBub wrote:

I'm usually the first guy to defend ol' HF, but I have yet to find an accurate analog measuring device in their store. One day, I went in looking for a square and tested out a bunch of that exact model and none were square, and a good many of them had inaccurate scales. They commonly did not start at "zero" at the corners.
I would go beyond the normal HF motto of buyer beware and say, just avoid them for something like this. If not, make sure you have a way of checking it for square and accuracy of the scale.
--

-MIKE-

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-MIKE- wrote:

Good points. I recall, however, from teaching Physics labs, that one should avoid using the end of a ruler -such as a yard stick (actually, we used "meter" sticks) - as a starting point. Start at the 1" mark and subtract one inch from the result to get the true distance. The reason is that the ends of measuring devices get boogered up and distort the beginning point.
For building such things as dog houses, it probably doesn't amount to a significant problem. Obtaining the measurement for a piece of glass, however, could be a WTF? moment..
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wrote:

...this goes for measuring tapes, too (maybe "especially" 'cause they get boogered regularly)...one of the first things I learned as a carpenter; "...burn an inch."
cg

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On 3/14/10 5:21 PM, HeyBub wrote:

Yeah, I think we all have learned to start at the one, at some point in our experience. But since the topic is "precision" framing square. I know that's an oxymoron. -)
In any case, I like to have at least one nice L square and one nice rule (from a combination square) that are each sanded "true zero" on each end and at the corners.
I often find myself with a square and a file, taking of the blister from a ding at the corner where it's been dropped on the concrete floor.
--

-MIKE-

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As I recall, a framing saw is calibrated square and a center punch is used to dent at the inside or outside of the V pint between the arms.
At the inside it spreads. Outside it pinches.
Martin
-MIKE- wrote:

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Doug White wrote:

L.S. Starrett is know for their precision and surprisingly there framing squares don't seem to be expensive. "Toolfetch" show the L.S. Starrett 36129 Fs-24 24"X 16" Steel Framing Square to be about $13.00.
http://www.toolfetch.com/Category/Measuring_Leveling/Squares/681-36129.htm
http://www.starrett.com/download/361_cat_70_p39_40.pdf
--
Jack Novak
Buffalo, NY - USA
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On 3/14/2010 11:12 AM, Doug White wrote:

buildings.
I use a solid triangle type square for all of the adjustments around the shop and on the shop tools. It has never failed me, and I use it all of the time. It also has been dropped more that I would like to admit. Based on adjustments made with this square I have made hundreds of picture frames with perfect mitered corners. (Maybe not all "perfect" but literally hundreds ;-) )
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wrote:

a squared + b squared = c squared? If you need something bigger than a 24" square, but not very often, then Pythagoras can help you out.
http://en.wikipedia.org/wiki/Pythagorean_theorem
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Upscale wrote:

Even easier is a 3x4x5 triangle, or multiples thereof.
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Doug White wrote:

for easy to follow directions.
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but you can't make them THINK !
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"Doug White" wrote:

As others have suggested, a judicious use of a center punch.
After that, it is 3-4-5 right triangle layout time.
Lew
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