Easily Assemble Miter Joints Without Jigs




About: I'm a grad student in astrophysics, specializing in building extremely high frequency radio telescopes and receivers. As scientists, we rarely have enough money to do things the easy or conventional way, so...
Miter joints are very common, popular joints in woodworking.

They're also devilishly difficult to make.  The 45 degree angles need to be cut dead-on to avoid gaps, and the gluing-up process is a horrorshow- the moment you clamp a miter-joint-to-be, the pieces slide around.

Various companies sell a host of jigs and tools for easing the problem.  But here's a method that has worked quite well for me, using nothing beyond normal shop tools.

What you'll need:
  • 4 mitered pieces to glue up.  You may be able to adapt this process to work on individual joints, but here I'll only talk about gluing up a rectangle all at once.
  • A table saw, with a sliding rip fence.
  • a decently straight board, long enough to clamp at both ends of the table.
  • Clamps
In truth, you don't really need the tablesaw and fence (you could use a regular table and two straight boards), but it does make life easier, as you'll see.

This Instructable was made at Xerocraft, the Tucson Hackerspace, and is intended to count towards our sponsorship from Instructables.


Step 1: Set Up Your Fences

Slide the fence to one edge of the tablesaw table, and lock it in place.  Place the straight board square against the outside edge of the fence, and clamp it down.

Now, you can move the fence anywhere else, and it will be parallel to the wood straightedge.

Slide the fence away, and lock it down the exact width (or slightly closer) than the width of one side of your rectangle.  With a piece of soft pine as a fence like what I've got here, I can set the gap slightly smaller, and the miter pieces will just stick when they're perpendicular.

Step 2: Glue Them Up!

It's always a good idea to do a test fit before applying glue- it's hard to go back later!

If everything looks right, apply glue to the miter areas, and place a clamp at each joint, as shown.  Get close to the ends- clamping in the middle of the horizontal members could bend them, messing up the joint.  Use a decent square to confirm that the angles are square- you can easily make adjustments.

A few notes: beware that some bar clamps tend to twist the pieces up.  Fancier furniture clamps like the two I'm using here have less of an issue with this.  You can also minimize this by accurately aligning the center of the clamp pads to the center of the board (if necessary, you can use a spacer to lift the glue-up off the table surface).  Lastly, light presure will reduce this flexing (clamping tightly shouldnt be necessary, anyways).

The glue should neither rust nor stick (badly) to the cast iron of the table surface, if you've treated it as you should- with simple furniture or bees wax.  This simple step eliminates the danger of damp air, and generally makes the saw easier to use, since wood slips over it very easily.



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    10 Discussions


    4 years ago on Step 2

    To prevent gluing your work to the table, put down a layer or two of wax paper.

    (I agree about rotating the pics. Please!)


    4 years ago

    I'm a cabinet make by trade and for fun and I love using miter joints for most everything. Its almost a daily procedure for me. an easier and faster way to glue up mitered joints is to use painters tape. lay out all the joints face up edge to edge. tape across the joints almost like your sticking it then one along the length of the seam. carefully flip it over to have access to the inside of the joint and glue. then just fold it all together. I've used this on every mitered joint you can think of. from frames to fully closed boxes. give it a try. it might change your miter building life lol.


    5 years ago on Step 2

    Would be nice if the pics were straight but the instructable gave me a bunch of ideas. Great work!



    6 years ago on Introduction

    No problem on the pictures I just saved on pc desktop opened in paint and flipped em 180 degrees :) . Awesome Idea and time saver. Not to this part just yet but I am learning alot, bookmarked this for future reference Thanks!!


    6 years ago on Introduction

    Good idea. Thanks for sharing.
    Reading this on my iPad, I just flipped it over and the pics look fine:)


    6 years ago on Introduction

    Thanks for this cool idea. Make my life a whole lot easier!


    6 years ago on Introduction

    Does it require mounting a table saw on the ceiling or onto a wall? (Just kidding) Your photos need re-orienting...

    1 reply

    I'm sorry! The photos were right side up on my computer, but the Instructables website flips them over weirdly. Maybe it doesn't like Ubuntu?