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Handling of Precision Squares

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  • #31
    So, if you put a square in space, it would warp instantly? That’s colder than cryogenic.

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    • #32
      In the Link by Mcgyver, there were many "holes" in the argument on both sides !
      You have people arguing because they read it in a book.
      Ever seen a book wrong ?--- If you say "No" then there are bridges for you to buy- real cheap !

      The problem (IMHO) is "Daffynitions"
      Dafynitions are definitions modified to suite the author/speaker- in other words ...what he understands and.... it may not be true for all !
      Before you pick a side in the Link mentioned , please realize that that argument was about ....CAST IRON

      Just like the differences in 4140 versus 1018 ( hey it's steel !) anyone who machines or had experiences with them both, know the difference.
      So too with Cast Iron, is it 2% Carbon or is it 1 1/2% Carbon or is it ???
      If you think all Cast Iron is the same......Don't....because just like steel......it has differences and that means variations in behavior .
      The discussion about Steel and temperature is the same , there are variables you may not know
      So blanket statements are absurd like " Water freezes at 32 Degrees F " ....really ! ..then why is water around the Titanic still liquid at 28 degrees ?
      We don't know what Starrett did when they made the square.....was it a new employee on the grinder ?..was it the assembler ?
      Was the steel stress relieved ? What was the temp of the storage room ?
      Try grinding a straight edge on a surface grinder and you will find out real quick what stress can do to iron or steel for straightness.
      Our world is not Static

      The big Error in the Link was the concept that Heat treatments solve stress/strain ..blatantly wrong !
      I guess they never were aware that Shock and/or Vibration which both relieve Stress and things can move . Was the square dropped at one time ?

      Rich
      Green Bay, WI

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      • #33
        Originally posted by eKretz View Post

        Only if the square is not perpendicular to what is being measured. The squares are very rigid in the other direction because of the relatively massive width of the vertical blade compared to its thickness. Think of it this way: set your square up against a vertical surface that is in alignment to the blade so that the base of the square is perpendicular to the surface in the axis that the square is sitting on. Now tilt the square so that the narrow edge lifts on one side. Will the blade stay in alignment with the vertical surface? Yes it will - as long as that base is set perpendicular to the surface it's checking. If it's not you'll see a larger gap form along the blade the further you move it from vertical. The warpage of the blade in that direction works exactly the same way.
        The issue with my square and it's slightly warped blade is when I check something I have to go straight in and keep the side of the blade square to what ever I'm checking. If I angle it a little like trying to read off the edge I'll never be able to close up the light gap. If this were a beveled edge square it wold be useless.

        Checking something off the edge with the square angled the concave side of the top of the blade will touch first leaving a gap the rest of the way down. Checking something off the convex side the bottom will touch first leaving the gap up towards the top. Checking against a known square precision ground angle plate.

        JL...........
        Last edited by JoeLee; 04-22-2022, 03:34 PM.

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        • #34
          Could some of the factors being discussed here be why precision squares, well any good squares, are ground on their sides? It provides a surface to align square to the work in the sideways direction so a slight bow will not matter.

          But then a granite square would be immune to this, wouldn't it?
          Paul A.
          SE Texas

          And if you look REAL close at an analog signal,
          You will find that it has discrete steps.

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          • #35
            Not going to go into the metallurgy thing, but...
            I have a precision 6" knife edge square that I use for precision stuff.
            It has no maker's mark, but I really looks like a Brown & Sharpe or a
            Starrett. Anyhow, it was my fathers that he used in carpentry shop
            in high school (overkill but my dad is where I get my overkill tendencies
            from). He got it from my grandfather. Anyhow, story time but not important.
            2nd Anyhow... I use it sometimes to square up work on the milling machine
            table when I am using a 90° angle plate. It makes quick work of setting work
            vertical, faster than indicating. So when I get the work plumb and the clamp
            hold down bolts snugged up, then I check the part for vertical with a test indicator.
            I am often surprised to find that I got my part square with the table within about
            .001" (one thou). I take my time and use a strong flashlight to get everything
            set just right. No point to make, other than I am often delighted and surprised
            how close you can get things set up with a good square. A little while ago
            I bought a shop made 8" square from a retired toolmaker on ebay. It is a better
            size tool for some of the work I do. I took it to work and checked it on the CMM
            and it was so close to 90° that I forget the actual measurement, but it had a lot
            of zeros before the numerals. I just love tools that allow me to do work.
            Even if it is not precision work. I have my favorite hammers and wrenches and
            chisels. Tools to me are more than a tool. They are my potential to solve any
            problem or complete any task. I was amazed how much I use my tractor with
            the bucket loader. I am also amazed how much I use 2" C-clamps for the odd
            job. I guess there are guys who do things and guys who play video games.
            Not saying any one is better or worse. Just saying it is nice to leave your mark
            on this earth with the time you are granted to be here. Tools allow you to do
            just that. A precision square is a great tool to get you there faster.


            --Doozer
            DZER

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            • #36
              Originally posted by Rich Carlstedt View Post
              .........................

              The problem (IMHO) is "Daffynitions"
              Dafynitions are definitions modified to suite the author/speaker- in other words ...what he understands and.... it may not be true for all !
              Before you pick a side in the Link mentioned , please realize that that argument was about ....CAST IRON

              J.........................................
              So blanket statements are absurd like " Water freezes at 32 Degrees F " ....really ! ..then why is water around the Titanic still liquid at 28 degrees ?
              ................................................

              The big Error in the Link was the concept that Heat treatments solve stress/strain ..blatantly wrong !
              I................................
              Rich
              Nope.

              The big problem is really the CONDITIONS. Like your "water freezes" example. I can say that water freezes at the exact same temperature that it boils..... and I would be perfectly correct! That is entirely true, IT DOES.

              Ever hear of the "triple point"?

              Under specific conditions, all three phases of water (liquid solid, and vapor) can exist in equilibrium.

              Forget "daffynitions", The entire fallacy is in ignoring the CONDITIONS under which the behavior exists. Certain treatments do certain things to certain materials, that are in certain states.

              As for heat treatments, there are all sorts of them that affect steel in ways other than hardening, "normalizing", "annealing", "sub critical annealing", "spheroidizing anneal", etc, etc. Each does a different thing, and does it to certain compositions of iron or steel.

              About all that can be said in general is that if you heat most steels above their critical temperature, and cool them slowly, they will be softer than they are if you cool them faster. How much softer varies with the treatment, and the steel. And there are exceptions to that, with various "conditions" that affect the results, (What steel or iron composition is it, how fast is a "slow cooling", etc).

              Heck, cold water does not even always put out fires.... it can make them worse, or have no particular effect.

              All that said, "in most cases", heat treatment can soften steel, and "in most cases", water can put out fires. The existence of exceptions does not mean that something is useless, a bad concept, etc. It does not mean you have to "freeze up" in indecision, helpless due to the wide variety of special rare cases that might theoretically affect what you are doing..

              CNC machines only go through the motions.

              Ideas expressed may be mine, or from anyone else in the universe.
              Not responsible for clerical errors. Or those made by lay people either.
              Number formats and units may be chosen at random depending on what day it is.
              I reserve the right to use a number system with any integer base without prior notice.
              Generalizations are understood to be "often" true, but not true in every case.

              Comment


              • #37
                Exactly Jerry ! and well Said !
                Unless you are dealing with specifically prescribed operations ( such as making Computer chips !) where you know all the variances in material and processes,
                it can be very difficult dealing with problems of the "unknown".
                Most issues in Home Shops involve unknowns. Maybe 80 or 90 % are solved using common information or common sense, but not all.
                The warped square is a good example. We as a group of responders don't know all the unknowns, but try to suggest some solutions.
                I guess I have a difficult time with seeing commentary about 'book" information. fellows may not understand that because it is in print, it may be in Error !
                I have done years of research on a subject not posted on these forums and can point to tens or more of books that are completely ignorant of the facts
                Human nature is what it is , and authors get lazy and print what was printed in another (earlier) book and never research or verify it beforehand.
                so when these things come up, it is important to point them out and I know you have done a good job with that.

                Just so you don't think I am blowing smoke, I have followed like a Bible the book ( and I have 3 ) Machinery's Handbook .
                No one in a home shop should be without it !
                So about 1993 I found a error in the 26th version and called the Editor and sure enough, they corrected the error as it was a mistake
                My job closely works with the expansion rate of steel and it was wrong in the new edition- and only in the first 26 th editions . they corrected it
                Non of the earlier editions had the error ..so even that handbook can be wrong at times.......Never say "Never'
                I probably am sensitive to comments about cast iron too, having had a friend who was a metallurgist at a iron foundry.
                Rich
                Green Bay, WI

                Comment


                • #38
                  Originally posted by Doozer View Post
                  No point to make, other than I am often delighted and surprised
                  how close you can get things set up with a good square...A precision square is a great tool to get you there faster.


                  --Doozer
                  I agree. It never ceases to amaze me how much precision work can be done with simple tools (squares, dividers, even combination squares, plumb bobs, etc.) Speaking of which, if anyone has a 3" firm joint Starrett dividers they're willing to part with, please let me know (I think they were model 139-3).

                  Comment


                  • #39
                    Originally posted by mgt3 View Post

                    I agree. It never ceases to amaze me how much precision work can be done with simple tools (squares, dividers, even combination squares, plumb bobs, etc.) Speaking of which, if anyone has a 3" firm joint Starrett dividers they're willing to part with, please let me know (I think they were model 139-3).
                    I actually would not get too hung up on it. The accuracy thing. We in general are making anything, metal or not to the nTH degree..

                    Here is the three footer I talked about. She is a beast, heavier than I remember. The guitar is my fav small six string so its there..

                    The two dollar bill is for you young folks that dont know what the size of a bill is... JR

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                    • #40
                      Figured you'd have one, the man with everything!

                      Nice square, have you ever used? i've got one as well, Browne & Sharpe I think.....also haven't used it. It was cheap enough that its worth for the look on guys faces when they realize what it is. No case though, jealous of that nice one you have there!
                      in Toronto Ontario - where are you?

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                      • #41
                        Originally posted by Mcgyver View Post
                        Figured you'd have one, the man with everything!

                        Nice square, have you ever used? i've got one as well, Browne & Sharpe I think.....also haven't used it. It was cheap enough that its worth for the look on guys faces when they realize what it is. No case though, jealous of that nice one you have there!
                        Hahaa, you funny Mr... I did get it for a fraction of what some folks think it might be worth. The B&S unit you have must be a real gem. I like B&S tools.

                        I did try to use it, once. I was setting up a column for a milling machine and tried to square the column up with it. Its just too fricken large Oh well.

                        It is a fun conversation piece though/ Not everyday you come across a 3 foot starrett square.

                        I meant to show pics of the actual square. It has a really odd way of attaching the blade to the base.. Non of my other squares are fastened like this odd ball.. JR


                        Its coated in LPS2 so looks are deceiving.

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