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Thread: Straight edge tool

  1. #1
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    Straight edge tool

    Iím trying to make a straight edge to keep in the shop and Iíve seen threads on making flat edges but I canít find them. I donít have a power jointer or a jointer plane. Can anyone direct me to a thread that describes techniques for checking for flatness over say 3 feet?

  2. #2
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    This method was intended for machinists but the method can be used to make wooden straight edges:

    https://www.scribd.com/document/5009...s-from-Scratch

    This method was used to make my winding sticks:

    Winding Sticks.jpg

    These were made from some scrap maple. The pieces intended for the winding sticks were ripped at an angle. This makes the bottoms wider for stability. They also stack together neatly for hanging.

    For checking over a long distance for flatness a string line can be used. Stanley Covington describes it in this post:

    https://sawmillcreek.org/showthread.php?258087

    It was used in my efforts to flatten a large piece of lumber:

    https://sawmillcreek.org/showthread.php?258087

    It is the 13th post in the thread.

    jtk
    Last edited by Jim Koepke; 12-11-2019 at 1:46 PM. Reason: changed some awkward wording
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  3. #3
    For checking flatness over 3 feet to woodworking accuracy, honestly you can just use a level or one of those 4 foot aluminum rules. That is what I normally use. There definitely are more expensive ways to get flatter, but they are kind of overkill for regular woodworking projects. For longer, I have a 5 foot and 8 foot pieces of 1 x 2 aluminum box beam.

    If you make a wood straight edge, make sure you use a stable wood. You could make a straight edge out of birch accurate to 0.0001" and it would probably have a visible twist a month later.

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  5. #5
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    Do you have any sort of handplane? You could use a #4 or #5 for a 3 ft edge.

    What I would do is match plane two sticks. Check them against each other, using the smallest feeler gauge. Keep match planing them until the feeler gauge will not go through when the edges are set against each other.


    A wooden straight edge is useful but only temporarily accurate. Of course you can always do a bit of match planing to restore the straightness. But I would recommend buying a 3ft steel straight edge, it is very useful and not too terribly expensive (~100 bucks from Lee Valley, accurate to 0.0015" I think). Longer than 3ft precision straightedges start to get very expensive, but they aren't needed as often in a woodshop. Making wooden straightedges can fill in those needs.

  6. #6
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    Straight edge I have been using is an old Tinner's Rule....36" long steel ruler, used by Tinsmith's to lay out sheet metal parts, when they made metal containers. Sold by Lufkin. Be on the look out for steel yardsticks, too.

  7. #7
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    Jim, scribd.com is a pay site. The author's site is gone, but I was able to locate a copy in the Internet archive.

    https://web.archive.org/web/20151026...ight_edge.html

    Thank you, Rafael.

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    That is a great find Rafael. Many years ago when the original post was found on a metal working web site it was saved as a web archive.

    The saying that things are forever on the internet does not always pan out.

    After a few of my favorite sites disappeared many of my remaining favorites have been archived just in case.

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

  9. #9
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    Lot of great advice and knowledge. Thanks for sharing.

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