Cut a Stepped Dovetail Splice (Koshikake Aritsugi)




Introduction: Cut a Stepped Dovetail Splice (Koshikake Aritsugi)

About: Happy in wood shavings YouTube: Patreon:

Used in traditional Japanese architecture, this joint is for joining lengths of sill beam, but it can also be used decoratively in furniture, etc. Find out how to prepare one.

I suggest you watch the video first, then read the steps given here

Step 1: Initial Preparation

The two joining ends of the components should be the same dimensions, and have squared corners, as shown

If they're not, grab a hand plane and sort that out before continuing

Step 2: Marking Out 1

First of all I like to rough draw the joint, as in the first photo', which should avoid any confusion later

Now either draw, or scribe as I do, the halfway height where the step will be. This goes on both components and should always be marked from the same faces (i.e. always mark down from the top, or up from the bottom, but never differently on each component)

Next draw in the dovetail on the top of one component. I'm using my shop made dovetail marking gauge (which I do sell on Etsy for anyone who's interested ;-) ) but you could cut a template out of a cereal box to use here - you just need to be able to repeat it later on

A line marked from the base of the dovetail down to the halfway mark, and one stepped back say ¼" from this around the bottom half, completes the initial marking out on component one

Step 3: Make Step in Component One

Saw down the halfway line to the step line, keeping the saw right next to the line, but within the waste below the line. We're trying to remove everything up to the halfway line, but nothing more

Turn the component around and saw, next to the step line, all the way to the halfway line

This should release a block, as shown

Step 4: Complete Component One

Transfer the dovetail marking from the top side, down the end and back under the notch you just produced

Now saw the waste away from both sides of the dovetail, as shown. Remember to leave the step in tact.

Step 5: Marking Up Component Two

Line the two components up, then lift and overlap component one onto component two. This allows the step and the dovetail socket to be transferred to the second component using either a knife or sharp pencil

Step 6: Cut Component Two

Saw the step off first. You can see this has been done in the first photo'

Mark in the dovetail socket shoulder lines (also photo' one)

Saw the slopes of the dovetail socket as far as possible, without sawing into the 'show' surfaces

Now chop out the majority of the socket waste, and finally clean the socket up by paring to the lines and into the corners

Step 7: Assemble

If you've prepared the joint surfaces well, the two components should go together with a firm push

You're done!

That really is all there is to it ;-)

Thanks for reading my Intructable. Don't forget there is a video of the process available on the first page

Let me know if you found it helpful or interesting, or just plain boring!



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    5 Discussions


    3 years ago

    That's interesting. I've never seen this joint before. I suppose you could also do a simple through dovetail, especially if the wood is thin. Thanks for these Japanese joints you've been posting! Good stuff.


    Reply 3 years ago


    The step does help to maintain alignment in a different plane to the dovetail, so it would depend on the specific application as to whether it's needed or not.

    Glad you're liking the Japanese joints - I have some more to do, but I tend to write up the Instrucables in batches now, and I'm due a little break ;-)


    Reply 3 years ago

    Cool, well I've followed you here on Instructables, so no rush. When you post them, I'll know! :)


    3 years ago

    After glue up is the final longer board strong and stable?


    Reply 3 years ago

    Fairly strong, but there are stronger splice joints that I will be doing in the future, so watch out for those. Some are already on my YouTube channel, in the Hand Cut Joints series (no. 39 & 40). I can't paste a link here, but you should be able to get to it through the video embedded above.