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Thread: Making a straigtedge

  1. #1
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    Making a straigtedge

    Having a fair amount of hardwood in the garage, I decided to make a straightedge as a method of adding to my puny skill level, and actually USE the tools I own.
    I selected a straight piece of Oak and began the process,
    The Oak is about 46 inches long, and I'll be blessed, but I just can't seem to get this piece of dead flat.
    I'm sure it's like getting to Carnegie Hall - "Practice, practice, practice" but I have high standards for my tools, and so far, this one doesn't meet it.
    I'm off by about 1/16 in the centre.
    Should I try it again in Old Growth Fir?
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  2. #2
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    Okay....so you have a 46" long piece of Oak that you want to use for a straightedge?
    Its out 1/16" in the center?

    what size is it ( all three dimensions.)
    is it the edge that you are talking about?
    is it concave or convex?
    How are you trying to straighten/flatten it. would this be with a handplane?
    What handplane?
    What are you using to check flat?

    You have left many blanks, and i don't like to make assumptions. The more information the better able we are to help.
    A photo is tremendously helpful in clarifying things.

    Generally speaking;
    If its concave in the center, don't plane the center. plane the ends and fair in to the center.
    if its convex, then plane the center and fair out to the ends.

  3. #3
    Agree with Mark's comments on where to remove wood. I made three straight edges at one time ,about 1990. Used
    tempered 1/4 inch tempered Masonite with white Formica glued on both sides with Weldwood (plastic resin glue). One
    8 foot, one 5 ,and one 3 . Business edge is tapered down to just the laminate. I hung them up for couple of weeks before
    ripping and filing. They have stayed true,since I don't lend them and keep them hanging. I'm sure they are not as acurate as Starrett stuff,but I
    can put bits of newspaper between two good edges and all are gripped equally.
    Last edited by Mel Fulks; 02-14-2019 at 2:11 AM.

  4. #4
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    The Oak is about 46 inches long, and I'll be blessed, but I just can't seem to get this piece of dead flat.
    Sometimes the stress in the wood changes the tension as it is removed causing the piece to warp or wander.

    If you are trying to make the edges true, the faces are not as important. If it is bowing along the edges, then you have the wrong piece of wood.

    Agree with Mark's comments on where to remove wood. I made three straight edges at one time ,about 1990.
    +1 on Mark's comments. The comment on making three straight edges is indicative of why to get one you may need to make three:

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

    This used to be available in full without having to divulge information.

    If you see what is taking place on the available page, the second page is superfluous.

    Besides, with making three two of them can be turned into winding sticks.

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

  5. #5
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    Thanks to all.
    Because of the onset of super snow conditions here, I haven't been able to get to my 5' levels in the normal workshop - my garage.
    Its about 46 x 3/4 x2 1/2, and there's no twist or bowing.
    Using handplanes, Stanley #5 w/original blade and chip breaker for the basic smoothing; a Record #7 for jointing and a #4 Veritas for smoothing and I'm drawing the straight profile on a piece of 1/4" plywood, then flipping it over.
    Yes, it's dished in the centre by about 1/16". I have taken the 2 end pieces down slightly, and I'll remeasure in the morning; I would have started on my jointer, but I can't work in the unheated garage right now, so I'm relegated to my basement and a workmate. Not the most stable of platforms, which is likely 60% of my trouble.
    Thanks for the replies.
    Young enough to remember doing it;
    Old enough to wish I could do it again.

  6. #6
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    Try taking your #7 and making full length passes until you get an even full length shaving. Then, using David Charelsworth’s method, mark a line about 1/2” in from each end. Using your #7 set for very fine shavings, plane from line to line until you no longer get any shavings...dust essentially. This should put a very shallow hollow in the edge..a couple thousands at most. Then take one or two full length shavings and check.

  7. #7
    A lot of guys who began with machine tools think the plane is supposed to make the edge flat. The plane is a help, but the worker has to discern the high spots and plane only those spots in order to achieve flatness. As Mark suggested, for a concave edge, you want to plane just the end sections. If you can't make a mental picture of the work to be done, make a drawing which exaggerates the hollowness. You will see that to fix the problem you will have to make short passes at each end, getting longer as you approach flatness.

    Incidentally, the Charlesworth method is an good example of machine tool thinking. He gives a procedure to follow which is designed to relieve the worker of thinking about what is going on and of developing the judgement which is needed for efficient work.

  8. #8
    May be a technique issue? You also have to be concerned about keeping the edge perfect 90 all along the length. I would suggest turning plane on its side, clamping down the wood and shooting the edge rather than doing it freehand.

    That said, IMO once you get it straight, I wouldn't expect a piece of wood that long to stray perfectly straight.

    That said, I've made winding sticks that seem to stay flat, but 20" in length. Even still, if I haven't used them in a while, I do a quick tune up.

  9. #9
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    You can establish a straight line by stretching a string if you need to.

  10. #10
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    Quote Originally Posted by Warren Mickley View Post
    A lot of guys who began with machine tools think the plane is supposed to make the edge flat. The plane is a help, but the worker has to discern the high spots and plane only those spots in order to achieve flatness. As Mark suggested, for a concave edge, you want to plane just the end sections. If you can't make a mental picture of the work to be done, make a drawing which exaggerates the hollowness. You will see that to fix the problem you will have to make short passes at each end, getting longer as you approach flatness.

    Incidentally, the Charlesworth method is an good example of machine tool thinking. He gives a procedure to follow which is designed to relieve the worker of thinking about what is going on and of developing the judgement which is needed for efficient work.
    I wont argue that Charlesworth begins with machined lumber but I will take issue with your conjecture that he relieves the woodworker of thought or judgement. If you watch him work an edge, you’ll see a carefully thought out and very efficient method of working it. It’s the opposite of an automatic or mindless procedure. In fact, the precision of his method is what I would use to make a straightedge hands down.

    to the op, I commiserate with the workmate in basement issue as that is where I started. It definitely makes careful work difficult.
    Last edited by Tony Wilkins; 02-14-2019 at 1:16 PM. Reason: Message to op

  11. #11
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    Quote Originally Posted by lowell holmes View Post
    You can establish a straight line by stretching a string if you need to.
    Stanley Covington once documented using a taught line and wooden gauge blocks to check for straightness.

    Quote Originally Posted by Tony Wilkins View Post
    [edited]
    to the op, I commiserate with the workmate in basement issue as that is where I started. It definitely makes careful work difficult.
    It may be easier to use the workmate to hold a 4X4 or 4X6 as a planing beam. This would provide some stability. Fitting legs at the ends of the beam would add more.

    My bench used to be a Workmate.

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

  12. #12
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    No one has asked how you are supporting this piece while you are planning it. It needs to be fully supported along the entire length. I know from experience that a piece clamped in work mate jaws doesn't get equal clamping pressure along its length.
    Last edited by Lee Schierer; 02-14-2019 at 2:20 PM.

  13. #13
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    Something seems wrong to me. If you're using a #7 on a 46" long piece you should not be able to have it 1/16" concave and still take full length shavings- it would just be clipping the ends even without you consciously trying. If you're taking through-shavings then it would be much more likely to have it 1/16" convex instead of concave, though that still seems excessive. Usually all of the fiddling is with the last .010" or so- a jointer plane should get you that far without much thinking.

    I wonder if you:

    -are overestimating the amount of error (gaps often look much larger than they really are)
    -have a poor reference to judge straightness (I did not really follow your explanation about the 1/4" plywood, it sort of sounds like you are referencing to a drawn line).
    -have a really bad sole on your jointer plane- like, extremely convex
    -have an extremely heavy shaving depth.

    Ideally you could get another stick of the same length and match-plane them together (put them both in the workmate vise with the edges flush and plane them as one surface), then check them against each other. If you are taking through-shavings with a decent jointer plane then the edges will either be flat, evenly convex or evenly concave (no waves), and when you put the edges together any gaps you see will be twice the actual error on each stick. It's not too difficult to work to .001" this way, and you avoid dealing with some imperfect reference.

    As for the workmate, it is not ideal but maybe you can brace it with some scrap lumber against a wall or something, in the direction your are pushing the plane. If you have anything heavy you can put that on the base. If you can stabilize the base the workmate "vise" is actually decent for this task. To compensate for the workmate you can take finer shavings which require less force, but you will need to get very sharp.

  14. #14
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    I think we need a workmate guide from @jimkoepke . I never did master using it but it sounds like Jim developed some strategies to help and make it work.

  15. #15
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    This is an important point. If the whole thing is not supported on a flat surface, you can get enough flex to drive you crazy if you are trying to get something absolutely flat or straight. Can happen even if you are on a flat surface if the underside is not flat.

    Quote Originally Posted by Lee Schierer View Post
    No one has asked how you are supporting this piece while you are planning it. It needs to be fully supported along the entire length. I know from experience that a piece clamped in work mate jaws doesn't get equal clamping pressure along its length.

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