A straight edge is an invaluable tool in your woodworking shop. Unfortunately, buying a quality straight edge can be very expensive. Here’s how to avoid that expense by building your own shop-made straight edge. The key is taking three different boards and using each as a reference to make sure you end up with three perfectly straight edges.


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  • Bryan

    Beginner here so don’t laugh if this is a stupid question but can’t you get a straight edge by using a jointer / Planer and not have to do the back and forth manual process of getting a straight edge on 3 boards? If I am way off on this please explain why this method should be used. Thanks for all the great tips and videos. I am learning a lot.

    • Al Amantea

      Well, Yes, and No, Bryan… While the main purpose of a Jointer is to give you a straight edge on a board, this only happens if you can verify the jointer tables are co-planer, the knives are set correctly to the table and each other, and you use proper technique on the jointer. So, how do you know if your jointer tables are co-planer? You check them with a straight edge. George just showed us all how to make one in the shop, instead of having to purchase one.
      You have to be careful with a jointer anyway, especially as a beginning woodworker. Use proper technique, and never lift or move the jointer by the tables. Jointers are notorious for causing a tapered board (all do to some extent), a convex board, or a concave board. Technique with a jointer can cause all three of those conditions, as well as having tables or knives out of adjustment. Jointers only reference off of one face of a board, the one you are working on, and have no way to make a boards faces or edges parallel to each other. (This is a job for the thickness planer) Jointers are a great way to give yourself a straight edge, and a 90 degree corner if you jointer a face and an edge, but will go wrong quickly if you aren’t careful.
      A straight edge has quite a variety of uses in the shop besides checking your jointer or layout duties. Straight edges (commercially available ones) are very expensive for guaranteed accuracy, and George just saved us all quite a few bundles… A Starrett 48″ precision straightedge runs around $250 to $300 (Lee Valley pricing). You can pick up a great used planer or jointer for that amount, or even a decent used contractor’s style table saw.
      Of course, if you already have a jointer, it might make sense to start the process by jointing one edge of all three boards to save time, and if the boards come out already straight, you are good to go.

      • Bryan

        That make sense. Thanks for the detailed explanation. I really appreciate it.

  • Gerald B. Curtis

    This was an interesting and very useful explanation about how to make a straight straight-edge.

    I have just completed three projects where there was a need to join four-3/4″ thick, 4′ long pieces of cherry. I am very new at this, so at least I began with a glue-line saw blade and an extended fence as I ripped very small amounts off the boards’ edges to try to assure straight and square edges. When I glued the boards up, I used four dowels per edge and TiteBond III Glue.

    I had tried hard, but I was aware, during glue-up, that the boards’ edges gapped VERY slightly. Of course, clamping pressure closed the very tiny gaps, but I learned later on this Site that I could expect TiteBond III v. another glue to relax and the closed gaps to open in time.

    I assume that the techniques displayed in making a straight straight-edge could apply to joining longish boards, albeit a tedious process.

    I have no interest (or funds) in buying a jointer or planer, but wonder if a track-saw appliance to be used on my worm-drive power saw with a glue-line blade would not assure a straighter edge than that which I produced on my table saw and glue-line blade, and one equivalent to the technique of making a straight straight-edge shown here.

    And, all that said, perhaps I should acquire a quality, long block plane and learn how to use it as the ultimate straightener of uneven board edges.

    Advice, please?

    • Customer Service

      Hi, Gerald! A track saw is a good idea. That way you’re creating your own straight line, rather than putting a less-than-straight edge against a rip fence on a table saw and, basically, tracing those irregularities onto the edge you’re cutting.

      A hand plane would be another good choice, provided you go through the learning curve of sharpening and using the plane.

      • Gerald B. Curtis

        Thank you.

  • Ethan

    Small tip for doing this, use different chalk colors for the different reference boards so the high spots stand out better. (less guessing is this the stain from old chalk, or chalk from a high point) You get it in packs of like 5.

  • Krams

    How does a level such as http://www.homedepot.com/p/Empire-True-Blue-72-in-e2G-Professional-Box-Level-E70-72/100356505 work for use as a straight edge. I use it in the store to pick out boards and it seems to be reasonable.

    Sorry for the brand and store specific link. Not intended as a plug for the same. It was more to illustrate what I was talking about…

    • Customer Service

      Hi, Krams! I’m not familiar with that particular product. In my experience, levels make pretty good straight edges. Maybe not perfect, but generally good.

  • David Riseberg

    I did this a while back, but instead of using wood, which I figured could change dimension between seasons, especially at different points in its width, I used metal bars. I used 3 – 1/8 x 2 x 48 inch bars from the home center. I will admit, it was a lot of work, but I now have 3 – 4 foot straight edges that are much less likely to go out of wack.
    The process for dressing them is the same, but instead of planing the edges, I used a file to take down the high spots. Trust me, it took a lot of filing to get them flat on all 3 bars referenced to each other. My final adjustments, to get them perfect, was to use lapping compound along the edge. To lap them against each other, I made a small wooden C clamp that I fit over the top and half way down the 2nd bar. I then used a small C clamp to keep it in place over the top bar. Then I proceeded to lap the bars against each other. When I was done, I had 3 perfectly flat edges.