Question for Domino experts?

[grobin]

I was thinking of trying to build a self locking joint with the Domino.  I am building open frame bookcases and shelving.  The goal is to be able to take the large units and break them down so its is feasible to move them.  They are fairly heavy made with Lyptus and typically will be 1m wide by about 2.1m tall and 318mm deep.  The shelves are removable and can be reversed (one side is stained walnut or is just Lyptus ply the other is painted a gloss white).

Now to the question.  The vertical riser is 19.8 mm by 38mm wide.  The narrow side is the front.  They are joined by stringers 19.8 by 114mm the narrow part runs parallel to the riser.  The tenons are oriented vertically and are 8x40mm.  I am thinking that if I set things up correctly that I can use the tenon from the side (connects to the back of the riser [19.8mm wide]) to lock the tenon from the front (connects to the 38mm side of the riser) to lock the joint.  This would require a small notch in the front tenon about 2mm at the joint then the side tenon can fit the notch.  Ideally I would like to just plunge the joint but I can't figure how to do so with the tenon in place so that I cut the notch in the tenon with the Domino.  Any one have any ideas aside from the obvious just cut the notch with a coping saw or power carver?

Sorry for the complex question.  (I guess I'm a little slow but can't figure out how to insert either a drawing or photo ???)

 

[Rick Christopherson]

If your goal is simply to lock the tenon in place with a notch in the edge of it, I would not use another Domino tenon to accomplish this. Instead, just use a standard dowel and drill its location. You'll have better control that way.

If the dowel is close to the same size as the tenon, then your idea of notching the edge of the mortise/tenon will be the strongest (as opposed to drilling a hole through the middle of the mortise/tenon). If you want this locking dowel to pull the joint together tightly, then simply offset the drilled hole slightly before gluing the tenon in the mating component.

 

[grobin]

Thanks, I thought of that; but I would need to offset the dominoes to do it and I'm not sure that I have the room.  That's why I was looking at using one domino to lock the other.

What I am going to try is to trial fit the dominoes and mark where the notch will go (looking at it I am going to have to make a 2mm notch in the face off an 8mm domino although; a 10mm would work better I think) and then position the post and stringer, mark their mortises for drawbore, take it back apart and make the notch then reassemble to check the fit and mark the dominoes for the drawbore.  I am going to do a test—hopefully, this afternoon, if it doesn't get windier (I am getting 30 to 40 knot gusts where I am working). 

The alternates are to make a blind drawbore in the wider piece of wood or run the mortise through and pin the protruding piece (I hate how that looks).  I find glue too slow and messy comparred to drawbore ;D

 

[grobin]

Well didn't get to try the test.  Wind increased a bunch from Beaufort 8 (Gale force) to 10 with gusts to 12 (70kn or hurricane force [scared])  when I moved out of shelter it was hard to stand up and 10"x1½" pine firing were  blown away unless secured.  Battened every thing down and came inside.  I love working outside but this is one of the downsides.  Hopefully it will not snow tomorrow and I can finish the test.  Every thing's in shape but I need to plunge the mortises and make the notch and joints.  Looking at it if this works I can make the notches quickly with a edge router and a jig.  I am going to loose some strength but I don't think enough to matter given that the weak spot is supported on the sides and will have 8mm± before and after the notch.