How to square a 6×8

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    Bill Henderson

    I bought some very old 6×8 doug fir beams which I intend to laminate for a thick workbench top. This is my first project using really big lumber. I started with my no 4 plane, and after a few days of frustration, I borrowed a neighbor’s thickness planer and, at least, got the two wide sides parallel for each of the beams.

    My problem is that I am still struggling to square the sides. As far as tools which could possibly be useful, I have a no. 4 plane, an old Bosch electric 3 1/2 inch hand planer, and a belt sander. I could use any help in technique with the hand plane for the best way to get a reliably square surface, as what I have been doing is not working very well. When I look online, I see lots of info on how to joint a board with an edge in the 1-2 inch range, but not in the 5-5 1/2 inch range.

    Any help would be appreciated.


    A big job for a little plane but doable
    Start in one corner and run diaganoly across the whole surface a plane width at a time repeat til flat then ck for square. And move on it will take time but will work. Keep your plane sharp and use an open mouth on it.

    Sven-Olof Jansson

    Dear Bill,

    Please may I for what it is worth, suggest borrowing techniques from timber framing, which have worked well for me when squaring poles.

    Use an ink line from one [short] edge to the other, touching the most narrow point of the two planed and parallel faces. Then, taking advantage of the faces being parallel, square down the edges, and use the ink line to mark on the other face. Planing down to the lines should result in a straight face that is square to other two planed ones.

    This task can be made less challenging by first planing along the edges down to the lines. That will create a ”ridge in the centre, to be attacked by cross planing. The risk for creating a groove is also reduced. Experience has taught me the that very frequent checks for cross flatness are beneficial

    If the thicknesser is still available, the hand planing chores are over. Otherwise, the remaining face can be gauged from its opposite, and then planed.

    Neither an electric hand planer nor a belt sander have been very useful to me for stock squaring and dimensioning. A #6 with a modestly chamfered blade for planing along the edges and final flattening, together with a dedicated scrub plane to do most of the cross planing, work well for me. As Mr. P. Sellers has shown, a chamfered blade transforms a #4 smoother to a scrub.

    For information I attach a link showing an ink-liner. Can’t imagine they won’t be available in North America. A chalk liner might be too inaccurate.


    Sven-Olof Jansson
    London, UK; Boston, MA

    Bill Henderson

    Thank you both for your responses, I just wanted to post a follow-up, in case someone came upon this later.

    As a starting off point, your ideas were great, but I was surprised at what ended up making the difference. After a while of struggling to square the width of the board throughout the length, I ground a problematic #4 plane’s iron to a curve and used it as a scrub plane. This made the diagonal passes go much quicker, and I was able to knock down high areas with a little more ease. Also, I stopped using a square after every pass, and started sighting the board from the end. I was astonished at how quickly this allowed me to see what I had to do and where. This probably had the biggest impact on my work, and I was able to square beams width and length in a matter of an hour instead of a whole morning. Then, I was able to do lengthwise passes with a #4 with a straight iron – the plane did not do a very good job straightening the board out lengthwise, but it was easy to see where I needed to adjust and do shorter passes to flatten out peaks.

    One last thing that really helped was to lay out my boards in the order I wanted them and when I went to straighten them lengthwise, I stopped worrying about how actually flat they were, and only worried about how they registered against the next board. I was able to get the job done pretty quickly without having a long, accurate straight edge or fiddling with string (which I tried and got frustrated with).

    This job only required exactly as much precision as it needed, so I got away with some shortcuts. I am looking forward to working with some smaller stock on my next project.

    Terry Gandy

    Ben Lehnert

    Since @sojansson mentioned the ink liners, I thought I might throw in a link to a video that I remembered seeing some time ago: ink liner by Mr. Chickadee

    As to your initial question: sure, why not use your hand plane. It’ll get the job done eventually!

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