Creating a Waterfall Joint With a Portable Circular Saw
 In PWM Shop Blog, Woodworking Blogs

Creating a Waterfall Joint With a Portable Circular SawIn continuation of the story of our live edge waterfall coffee table, today I will show a way to accurately cut a miter joint on a live edge slab with a circular saw.

If you do not have a table saw you can use a circular saw pushed against a clamped guide to saw the miter. To ensure an accurate miter you will have to saw at 45 degrees across a path set at an appropriate right angle in relationship to the center line of the slab. And you will have to make sure to push your saw against the guide you clamped to the slab.

This is how you can do it:

  • Lay your slab on a stable surface with a reliable sacrificial liner under it, such as two 2x4s or a plywood sheet.
  • Draw a center line (A, shown below) from the the slab’s foot edge (the crosscut at the end of the slab) to the the opposite head edge.
  • At the place you want the miter to be, draw a right angle line to the center line with a carpenter’s square or a draftsman’s triangle (B).
  • Clamp your circular saw guide adjacent to line (B) and saw the slab to form the first part. This  part can be the top or a leg depending on your decision which to cut first.
  • Unclamp your saw guide and reposition it on the remaining slab.
  • Cut the slab going from the opposing side to form the second 45 degree miter.
  • Now you have two parts with complimentary miters that once joined together (after some necessary inner reinforcement, which I will talk about later) create a waterfall effect.
    waterfall-slab-mitering-1

Next time: how to cut waterfalls on the table saw.

— Yoav Liberman

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Showing 8 comments
  • daddywoofdawg

    where do you place the fence for the second cut?

    • Yoav Liberman
      Yoav Liberman

      When you miter the other bank of the joint you have to saw from the opposing live edge, and you do it by clamping your guide onto the remaining portion of the slab. What you will need to do is to migrate the guide and the saw to the part that was just sawn off. If you first clamped the guide to the leg portion relocate the guide to the top portion and vice versa.

  • Italicus

    Hi Yoav,
    Great info on this popular joint and something I have often wondered about but never tried. I would be inclined to try this on dimensional lumber first just to get comfortable with the process before I would feel comfortable tearing into a precious slab.

    • Yoav Liberman
      Yoav Liberman

      Absolutely. It is always a good idea to try a new technique on a less expansive/unique lumber before implementing it on the real deal.

  • Wilbern Garrett

    BEWARE The tapering width. With a 2″ slab, the interior-most edges of the live edge at the 90 are from
    4″ apart and are likely to be of quite different widths there. I will do two things: (1) select a slab with
    much less taper. (2) favor one live edge and make my “centerline” parallel to that edge to minimize
    that 90 interior mismatch. This is likely to give you a front/ back situation on your table/bench but that’s better than having two back sides. This is a great project for a poor boy like me, more time than money.
    I would like to hear some ideas on the joinery here – to be strong enough for use as a bench, yet hidden.

    • Yoav Liberman
      Yoav Liberman

      You are correct of pointing out that mitering a live edge slab (tapered, thick, or in fact any live edge) can result in a discrepancy or misalignment of the miter’s inner corner. The way I have dealt with this abrupt flow of grain in the past was to reshape the miter fold with gouges and sandpaper until it looked organic. After the edge’s “enhancement” was complete I used die or stain to fully bland the doctored area with the natural edge that surrounded it. I will include some pictures to demonstrate my technique in the next post, or the one that follows.

  • Jim McConnell

    Quick question: It looks like it would make the most sense to cut the miter on the “free” piece first (in this case the top) because then the registration face of the guide would still be attached to the same place on the other piece allowing an accurate second miter. Am I reading this right?

    • Yoav Liberman
      Yoav Liberman

      Hi Jim,
      I am not sure if I fully understood your question. But to clarify things a bit here are a few guide lines:
      A. In an ideal situation the live edge slab should be jointed and planed, or at least be flattened and straightened as much as possible.
      B. I do not advise clamping both sides of the slab to the sacrificial base. I think that clamping one side (you can decide which one to begin with) to the saw guide and the sacrificial substrate is enough. If both portions of the slab are to be clamped down the saw blade might get pinched by both “banks” of the mitter as the miter progress. This is due to inner forces and stresses in the slab that can manifest themselves as the slab is separated. I anticipate it will happen if the board is not absolutely trued.
      C. After the first miter cut is done you will have to un-clamp the guide and relocate it to the other bank of the miter at 180 degrees rotation. You have to do so because your circular saw only tilts in one direction and to make a miter cut on the other portion of the slab the saw have to cut from the opposite direction, hence the guide has to be rotated.
      I hope that I was able to help and clarify things, but please don’t hesitate to ask any additional questions.

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