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Thread: Another use for my Shooting Board

  1. #1

    Another use for my Shooting Board

    While squaring up my Incra miter gauge, I realized that ALL THREE of my clear plastic draftsman triangles were out of square by a degree or so. Put them on the shooting board, got out my LV Shooting Plane - and voila! - perfectly square by each of the 3 tests I used to check!
    "All that is necessary for the triumph of evil is that good men do nothing."

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  2. #2
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    Nice "out of the box" thinking. If that would only work for my metal one that is 'out' by about 1.5°. I'll just scribe and file it, if it's not too hard.
    Jeff

  3. #3
    Not too hard, but not too accurate either, I am afraid. Filing or sanding an edge works only if your tolerance level is not high.

    Simon

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    Quote Originally Posted by Simon MacGowen View Post
    Not too hard, but not too accurate either, I am afraid. Filing or sanding an edge works only if your tolerance level is not high.

    Simon
    Oh no, disagree.

    You can achieve great results file-working metal.

  5. #5
    Quote Originally Posted by Kory Cassel View Post
    Oh no, disagree.

    You can achieve great results file-working metal.
    You are talking about squares/90*, right? Please state the tolerance level of your "great results."

    Simon

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    Getting well within 1 degree by working the slot of a combo square is easy. Working the blade of a try-square to within the margins of a sharp pencil line is slightly more challenging by very doable with a file. Gap free joints and accurate woodworking machine set up can most definitely be achieved by hand working your squares with files. If you're talking about .001" over a 36" blade, then it can still be done by hand, but not easily. Following the file-work with a burnisher makes for a nice smooth marking surface. Tuning squares by hand is a matter of patience and precise checking but is not so limited by the inaccuracy of files as you seemed to indicate. No offense intended if I misunderstood your post.

  7. #7
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    More than one of my try squares or combination squares have been vastly improved with carefully thought out use of a file and scraper.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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    ALL THREE of my clear plastic draftsman triangles were out of square by a degree or so.
    Just for future thought and reference:

    My guess is they were out by less than a degree. 1º over 12" is 0.2". 3º over 12" is more than 5/8".

    Even a not so well trained human eye would see that much of an error.

    FWIW, my shop made triangles were squared via shooting board:

    30º - 60° Triangle.jpg

    They come in handy at times.

    The rosewood triangle is not shop made.

    jtk
    Last edited by Jim Koepke; 12-02-2018 at 2:54 PM. Reason: wording & note on rosewood triangle
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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    Quote Originally Posted by Jim Koepke View Post
    More than one of my try squares or combination squares have been vastly improved with carefully thought out use of a file and scraper.

    jtk
    Bring a scraper into to equation and you can achieve accuracies so good they become difficult to measure. Did you train as a machinist Jim?
    Last edited by Kory Cassel; 12-02-2018 at 2:52 PM.

  10. #10
    Quote Originally Posted by Kory Cassel View Post
    Getting well within 1 degree by working the slot of a combo square is easy. Working the blade of a try-square to within the margins of a sharp pencil line is slightly more challenging by very doable with a file. Gap free joints and accurate woodworking machine set up can most definitely be achieved by hand working your squares with files. If you're talking about .001" over a 36" blade, then it can still be done by hand, but not easily. Following the file-work with a burnisher makes for a nice smooth marking surface. Tuning squares by hand is a matter of patience and precise checking but is not so limited by the inaccuracy of files as you seemed to indicate. No offense intended if I misunderstood your post.
    No offense taken here (or any elsewhere when I post my opinions. Disagreements mean we don't belong to a cult). My point is that it is not too hard (as the other poster pointed out) to try squaring something, but it is not a reliable method if the tolerance level is high. The accuracy of a common engineer’s square is 0.001" per inch of length. It is not 0.001" over the length of the blade.

    As a reference, a CNC-made square I recently came across carries this spec.:

    "Guaranteed Accurate: Machined on high-precision CNC machining centers and made from thick precision aluminum tooling plate guaranteed square to within .001” over its 18” length as verified using an automated CMM (Coordinate Measuring Machine)."

    Simon
    Last edited by Simon MacGowen; 12-02-2018 at 3:19 PM.

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    Quote Originally Posted by Simon MacGowen View Post
    No offense taken here (or any elsewhere when I post my opinions. Disagreements mean we don't belong to a cult). My point is that it is not too hard (as the other poster pointed out) to try squaring something, but it is not a reliable method if the tolerance level is high. The accuracy of a common engineer’s square is 0.001" per inch of length. It is not 0.001" over the length of the blade.

    Simon
    Hand filing is not too inaccurate to make a square that will mark good, gap free joint layout. You keep using that word tolerance and trying to obfuscate the issue and rattle off numbers to make it look like I don't know what I'm talking about. If you want to list the applications for which it is not suitable, that's fine but correcting a woodworker's shop square is not one of them. That's what is seemed like you were saying in your original post. If you're saying that a hand filed surface is not accurate enough to suit your needs, then I'll let that go. If you were trying to say that one can't rework the edge a square to be accurate enough for shop use as a woodworker, I'll say we agree to disagree and leave it at that. The flatness tolerances that can be achieved with skilled hand work in metal would probably surprise you if you were to talk to a machinist. I wonder where you could find one.

  12. #12
    Quote Originally Posted by Kory Cassel View Post
    You keep using that word tolerance and trying to obfuscate the issue ...
    I did not try to obfuscate anything. This is what I said, "Filing or sanding an edge works only if your tolerance level is not high."

    100% clear that my very first comment was made with reference to tolerance.

    Simon

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    Quote Originally Posted by Simon MacGowen View Post
    I did not try to obfuscate anything. This is what I said, "Filing or sanding an edge works only if your tolerance level is not high."

    100% clear that my very first comment was made with reference to tolerance.

    Simon
    So were you trying to say that the tolerance that can be achieved by filing would not serve for a 6" square?

  14. #14
    Quote Originally Posted by Kory Cassel View Post
    So were you trying to say that the tolerance that can be achieved by filing would not serve for a 6" square?
    Not sure if you know. Your question is an indirect acknowledgement of my point that it is all about tolerance. Filing or sanding a shorter blade may bring out a better outcome or a higher tolerance.

    If your responses are trying to tell us you are very good with filing or using files to square things up, I have not ruled that out in any of my previous statements.

    Simon

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    Filing or sanding an edge works only if your tolerance level is not high.
    About the best resolution of my measuring devices is ~0.001". It has allowed me to file, sand and scrape a 12" square to within one thousandth of an inch over its length. Any closer than that and it would have to be measured in ten thousandths of an inch.

    The accuracy of a common engineer’s square is 0.001" per inch of length. It is not 0.001" over the length of the blade.
    So it seems the 'fine tuning' of my squares is to a higher tolerance than a common engineer's square. This is likely a high enough tolerance for the average woodworker.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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