Cross Lap with Mitered Corners-Part 1

Well, I might as well start this journey.

Cross Lap with Mitered Corners

cross_lap_mitered_corners-pdf

cross_lap_mitered_corners

I have, as yet, been unable to find any written reference to this joint.  I have seen an example of it from two sources.  One being a video by Jay van Arsdale where he shows an example and Chris Hall has utilized the joint in a couple of projects that he has posted about on his blog,  here for example.

cross_lap_mitered_corners_assembled

The joint looks simple, but the addition of the mitered corners increases it’s complexity more than I anticipated.  The mitered corners also adds a great deal more strength to the joint than I had anticipated as well.  Even poorly executed examples, riddled with gaps, were quite rigid and resisted torsional loads and required a mallet for disassembly.  An addition advantage of this joint is that the long corners of the work pieces can be chamfered, up to the depth of the miter, before final assembly.  The mitered corners automatically create the appearance of an internal miter and gives the impression that the pieces wrap over each other.

I chose to execute this joint in material that is square in section.  It simplifies the layout and also happens to be what I typically use for my “post and panel” type projects.  The joint could be used with material of differing section profiles, but the layout becomes more complex due to the varying angles of the miter.  In square stock,  the miter is a plain old simple 45°.

cross_lap_mitered_corners_layout

As noted in my drawing above, the offset distance (O) that creates the inner square and miter, can be any distance of your choosing.  Considerations should be made for any additional joinery that may take place.  The insertion of a pin or a thru tenon from an adjoining structural member.  As in a corner joint where the third piece would tenoned thru the cross lap and wedged.  Thus locking all three members of the corner together.

Side note:

When I cut practice joints I do so with as little aid from knife lines, gauges and jigs as possible.  I lay out the joinery with a square and ink.  Saw and chisel to the lines to the best of my ability.  My rational is that my skills will be strengthened on several levels.  My layout ability, sawing and chiseling should all improve with each practice joint done in this manner.  For actual project work however, I’ll utilize all manner of aides at my disposal.

The layout is fairly simple on this square sectioned stock.  Both pieces are identical in their layout.  Please overlook my smeared ink lines.

IMG_1993

One thing to keep in mind with this, and all joinery, is preservation of the layout lines.  What I mean by this, is that the joint should be cut in a way that preserves the layout as long as possible.  Three faces of each workpiece will have material removed.  This needs to be done in such a way so that you do not lose the depth line for the lap before that section of material is removed.

To start, I sawed to the depth lines on all three faces of the layout.

Then I removed the center section that creates the lap portion of the joint.

IMG_1995

The rest is chisel work.  Carefully paring to the layout lines.  The miter should be a tight friction fit.  Too tight and you run the risk of one splitting out material at the mating corner.  The center section can be as tight as you dare make it.  Since the compression in this area is against the end grain, there is very little chance of a split or fracture.  You do need to pay careful attention when making this joint close to the ends of a workpiece.  There is a danger of splitting off the section between the joint and the end of the workpiece.  Always cut a sample joint in the material you plan to use so that you can get a feel for the compression rate.  Soft woods can compress quite a bit.  Hardwoods may not compress at all.

My first four attempts at this joint failed miserably.  Gap after gap after gap whenever I assembled the joint.  My material is from 2x construction lumber and compresses a lot.  So I found it best to leave all of the layout lines intact when sawing and chiseling.  I also found no effective way to saw the miter.  You can’t just saw across the diagonal since you need to leave the layout line on each corner.  At any rate, I had far better luck paring the miter.

IMG_1998

My layout for depth looks a little off.

IMG_1999

What it looks like with the layout lines removed.

IMG_2001

With a chamfer added to the long edges.

IMG_2002

Joint #5 came together acceptably well.  There is still a lot of room for improvement, but I’m getting there.  Another twenty or thirty practice joints and I may begin to feel comfortable with this joint.

My gallery of gaps and shame.

IMG_2017

This joint is a keeper and I can already think of ways that I can work it into furniture projects.  It is a challenge though.  A 45° paring guide will prove quite useful when it comes time to put this joint to actual use in a project.

I hope that you at least give this joint a try, if for nothing more than the challenge.  Who knows, you may find a use for it too.

Greg Merritt Part 2

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35 Responses to Cross Lap with Mitered Corners-Part 1

  1. Kinderhook88 says:

    Adding the chamfer really makes this joint shine. Nice work, Greg! I’ll give this one a try when my bench is ready.

    • Greg Merritt says:

      Thanks. The ability to chamfer the pieces is a big bonus with this joint. I have a long way to go before I’ll feel comfortable with cutting this joint. Do give it a try. Its a little addictive.

  2. Wesley Beal says:

    I’m glad to see you’re including a copyright on the pdf. When you’ve put all these together, I’d pay money for them in book form. Shoot, I think a coffee-table book would be an excellent format. Large pages and good paper would allow the crispness of those drawings to come through, with the facing page having the textual description. Could be a $60.00 book, and worth the money.

  3. Wesley Beal says:

    Reblogged this on wesleyworkswithwood and commented:
    If somehow you find yourself on my blog, and you aren’t already reading Greg Merritt’s, then get over there and read the first description in a series he is doing on joinery. Excellent stuff.

  4. skiroy56 says:

    #5 looks very good. Yes practice may not make you perfect but will make you proficient.
    Keep up, enjoying the posts.
    Laurence

  5. Stan says:

    Enjoyed the post.

    A very old joint indeed, used commonly in wooden religious structures, ceiling grid frames, and high-end joinery (tategu).

    Of course, it has 2 advantages. The first is of greatest advantage in exposed structural timber joints because, as the members unavoidably shrink in width over the decades and centuries, instead of creating an unsightly gap, the chamfers make the joint look tight.

    The second advantage is one that was referred to in another comment. It permits the chamfers on cross-pieces in joinery (especially doors, windows, shoji, and any wooden latticework) and furniture to match exactly for a very refined appearance.

    I had never considered that it might add rigidity… Seems like it would be significantly weaker in bending and shear due to reduced cross section. Do you know of any reports on comparative destructive testing?

    Keep up the good work!

    • Greg Merritt says:

      Thank you and thank you for the background information as well.
      No, I have no finite structural data as to the the strength of this joint. Just making an observation based upon other furniture-scale joinery. Would I build a ladder using this joint? Heck no, but it will serve well in furniture building. 🙂

      • Stan says:

        The joint was commonly used in window and door mullion construction. A very useful joint.

        Here in Japan, there are specialized tools called “kudegosgi” for cutting the joint quickly in smaller latticework pieces, especially shoji screens. Hard to find nowadays, I am sorry to say. For larger members, the 45* jig you mentioned is commonly used. They register off both the top and side of the member at the same time. Easy to draw, hard to describe.

        A multi-Ura Tsuki chisel with a long blade works best due to the greater register area. The chisel’s flat must be very very flat, otherwise the cut will wander out of plane. As you can tell, I too am fond of this joint, and have made hundreds over the years. Stan

        • Greg Merritt says:

          Thanks again.
          I have seen a similar example of that type of plane in one of Desmond King’s books I believe.
          I plan to do a follow-up post and have a paring jig exampled as well as a chamfering plane, hopefully.

  6. Sylvain says:

    Well done.
    Others have already made comments I would have done.
    The chamfer is the simplest of the molding profile and the only limitation here is the width of the profile.
    Sylvain

    • Greg Merritt says:

      Thank you Sylvain.
      Yep, any molding profile will work, but the simple chamfer is accessible to everyone with a hand plane.
      There are a lot of possibilities with this joint though.

  7. Andrej says:

    Love the detailed sketches and your explanations. However, I did not quite understand, why the miters give the joint more strength. Could you elaborate on that? Thank you 🙂

    • Greg Merritt says:

      Thank you.
      Generally speaking, the more bearing surface and triangles you can build into a joint, the stronger it will be. The miters, in this instance, add both over a basic lap joint.

  8. burenschinder says:

    Hi, I meant to say this much earlier but: I really love your blog and this post has, again, be very inspiring. You got me back into working with soft woods. I got blasted results and bought into the whole “soft wood is bad”-school of thought but after seeing your projects and the nice details and joinery you do I decided to give it another shot. Bloody brilliant! Who knew what you can do with sharp blades in this stuff… Carry on, man. I will be reading. This post has given me a lot of great ideas about chamfering already.

    • Greg Merritt says:

      Thanks so much! Your comment means a great deal to me. One of my main goals with this blog is to make woodworking accessible to everyone. My material choices are of paramount importance in making this happen. Just about everyone can locate and afford softwood. It is good to hear that some of my “crazy” ideas are taking root out in the world.

  9. Jonathan says:

    Greg, your drawings are fantastic. I thought that they must be computer generated until you mentioned “sketch”. Wow! My drawings are most suited to crayons.

    All the best,

    Jonathan

  10. Johan says:

    I remembered I had seen this joint in a book before so I had to back and find it again. “Woodwork Joints: How they are Set Out, How Made and Where Used. by William Fairham” page 21 the book can be viewed free on gutenberg.org. In the book he states that this joint were used for molding.

    Great drawings and work as usual.

    Cheers Johan

    • Greg Merritt says:

      I believe you have it. Thanks for the reference!
      With the information from Stan above and your reference, the overwhelming evidence is that this joint has been used primarily for applied moldings. Of course, as is my SOP, I have far different ideas as to its use. I’ll post about those soon.
      Thanks for the kind words as well, I appreciated it.

  11. Metod Alif says:

    Chris Hall uses this joint in his current project – as well as in earlier works. He is not shy in using calipers and guide blocks in pursuit of precision/excellence.
    This is (my) problem with the layout lines: Even the thinnest ones are still too wide. By keeping track of the ‘true’ edge of the lines (the edge next to the ruler) you can get to the desired accuracy faster. In short: I strive to cut/pare to the true edge.
    Best wishes,
    Metod

    • Greg Merritt says:

      It depends on the material you are working with. I work predominantly in soft wood and there is a good bit of compression. So, sometimes I leave the line, sometimes I split the line and sometimes I take the line. The trick is learning when to do which. You also have to be very consistent with how you lay out your joinery. The line that you use also needs to the same width at all times.

  12. Metod Alif says:

    I very much agree that the material dictates how how close is good enough. My present preference is to draw a layout in such a way that the lines must stay untouched. Individual method is not as important as the final fit.
    Best wishes,
    Metod

  13. Brian Eve says:

    I’m totally going to practice this joint.

    Can you walk us through what you learned from your test pieces? It might be nice to hear what you did to tighten up the joints.

    BTW, I agree with the sentiment about the book. Your drawings are good. You might even consider self-publishing an e-book. You’ll do most of the donkey work here on your blog.

    • Greg Merritt says:

      I’m glad that you are going to give this joint a try Brian. I’m working on a follow-up post right now and should have it up sometime today. In it I’ll go over what I have learned so far.
      I must admit, the idea of a book is very appealing. I have a long way to go though before seriously considering it. Your support for the idea means a lot. Thanks.

  14. Pingback: Cross Lap with Mitered Corners-Part 2 | GREG MERRITT – BY MY OWN HANDS

  15. potomacker says:

    I started tackling this joint based on Chris Hall’s example and then you offer this insight and explanation. The universe is telling me something, it seems. I am still looking for any insight how to determine the width of the abutments, Chris Hall’s term, proportionally to the overall dimensions and how to step them off from the outside lines. I usually mark my pieces with a knife, yes, even in SYP, but this joint required me to purchase and 0.5 mm pencil.
    You’ve certainly helped me to feel less alone in my endeavors.

    • Greg Merritt says:

      It took me a few tries to get a handle on how much of the line to leave and take at each of the intersections. Of course it will vary evertime I change material. That is part of the fun, right?
      The miter portions can be set out propotionally, as 1/4 the width for example. I have yet to find any hard and fast rule though.
      Good luck on your journey and don’t let any early missteps worry you.

  16. I tried that joint years ago in round cedar, for a fence panel outside. Basically, I laid out a square, then sawed the diagonals first, using those cuts to track the miters. Later, it occurred to me that if the miters had a bit of slope they could be fitted up without increasing the gap.

    • Greg Merritt says:

      Sounds reasonable to me. I’ll give it a shot when I get a chance. I have came to the conclusion that scale plays a significant role as to how this joint should be cut. I hope to put this joint to use in a project sooner than later.

If you don't comment this is just a fancy way for me to talk to myself.

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