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Thread: Accurate Hole Placement Only Where You Need It

  1. #1
    Supporting Member rgsparber's Avatar
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    Accurate Hole Placement Only Where You Need It

    This article is for people new to metalworking.

    Murphy's Law states that when you drill a hole, it will be in the wrong place. But if you drill a hole that passes through two objects at the same time and place, it is one hole so must be in exact alignment with itself. Furthermore, if you lock these holes in the two objects together and repeat the process, the second set of holes must be in perfect alignment with each other and with the first set of holes. You can drill any number of holes and they will all be in alignment without doing any precision measuring.

    Did I confuse you? This concept is better explained in the text.

    If you are interested, please see

    https://rick.sparber.org/HoleAlignment.pdf


    Your comments are welcome. All of us are smarter than any one of us.


    Thanks,

    Rick

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    Rick

  2. The Following 2 Users Say Thank You to rgsparber For This Useful Post:

    mklotz (02-27-2019), Seedtick (02-27-2019)

  3. #2
    Supporting Member mklotz's Avatar
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    Now, that's a really nice explanation of the way a seasoned craftsman thinks through the mechanics of a problem in a way that provides a memorable technique for future work.

    Since you mention that your treatise is for "people new to metalworking", you might want to add a few words of caution about starting the hacksaw cut on the edge of the angle iron.

    Good cutting practice is to keep at least three or four teeth in the cut all the time. When the cut as shown starts you have only one tooth in the cut and run the risk of breaking teeth out of the blade. DAMHIKT

    For steel, I usually file a starting notch so the blade is initially cutting on a small flat. For aluminum, I just lower the blade very slowly into the material. As the teeth touch they are only taking a tiny, low stress bite and as they slowly lower they create a flat that approximates the filed notch. (And, of course, aluminum is much softer so less reaction force on the blade.)
    ---
    Regards, Marv


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  4. #3
    Supporting Member rgsparber's Avatar
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    rgsparber's Tools
    Quote Originally Posted by mklotz View Post
    Now, that's a really nice explanation of the way a seasoned craftsman thinks through the mechanics of a problem in a way that provides a memorable technique for future work.

    Since you mention that your treatise is for "people new to metalworking", you might want to add a few words of caution about starting the hacksaw cut on the edge of the angle iron.

    Good cutting practice is to keep at least three or four teeth in the cut all the time. When the cut as shown starts you have only one tooth in the cut and run the risk of breaking teeth out of the blade. DAMHIKT

    For steel, I usually file a starting notch so the blade is initially cutting on a small flat. For aluminum, I just lower the blade very slowly into the material. As the teeth touch they are only taking a tiny, low stress bite and as they slowly lower they create a flat that approximates the filed notch. (And, of course, aluminum is much softer so less reaction force on the blade.)
    I just slowly feed the blade down and, yes, have broken teeth... You are right to call me out on it and the updated article is available.

    Thanks,

    Rick


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