Stacked Domino Tenons

[Birdhunter]

I'm joining a 1/4 to a cross member made of 2 1X4s glued together. So, it is an "L" 90 degree joint that I want to make using 4 tenons.

I did the first set of tenons down 15mm from the top of the two boards and got a perfect joint.

I did the second set of tenons down 30mm from the top and that set was off by a couple of mm.

Is there a trick to doing double sets of tenons? Is there a video showing how to do it?

 

[Michael Kellough]

The lower mortises are off relative to one another because the fence is not perfectly square to the elevator posts. This is a real weak point in the design of the Domino.

If you can't get the fence to be square you'll have to use the next wider setting for those mortises that are much farther away from the fence. The higher the fence is on the posts the more lateral displacement of the mortise and the mortises are displaced in opposite directions whine assembled.

 

[Birdhunter]

I guess I messed up on stating the problem.

If I put only the top row of tenons (2) in the mortises and try the joint, the two boards are perfectly flush.

If I put tenons (2) only in the second (lower) row, the joint has one board a tad higher than the other. However, the mismatch looks to be uniform across the width of the board. It doesn't look like the fence wasn't square.

I cut the top row of mortises in both boards without moving the fence, then reset the fence for the deeper set of mortises and cut both boards without moving the fence.

I'm suspecting I'm not holding the Domino exactly right when I cut the lower set of mortises.

 

[jacko9]

I guess I messed up on stating the problem.

If I put only the top row of tenons (2) in the mortises and try the joint, the two boards are perfectly flush.

If I put tenons (2) only in the second (lower) row, the joint has one board a tad higher than the other. However, the mismatch looks to be uniform across the width of the board. It doesn't look like the fence wasn't square.

I cut the top row of mortises in both boards without moving the fence, then reset the fence for the deeper set of mortises and cut both boards without moving the fence.

I'm suspecting I'm not holding the Domino exactly right when I cut the lower set of mortises.

I've cut twin domino joints just like this a lot and one thing that I learned early on was to use spare stock behind my work pieces to steady the fence.

I use twin stacked 4mm dominos in all of my small cabinet drawer blade joints and with a steady plunge with a fully supported fence I don't have any issues.

Jack

 

[waho6o9]

A few pictures would be nice.

Thanks

[smile]

 

[jacko9]

A few pictures would be nice.

Thanks

[smile]

See above, is that the picture you were looking for?

Jack

 

[Stoli]

I think pictures of the original poster's results are what was being requested.

One place that errors like this can creep up is placing the fence on both sides of the stock, and assuming that both pieces are the same size.  The original post indicated that the same side was used, but the fence height changed, which would be the correct approach.

 

[Birdhunter]

I used the same reference side.

 

[Birdhunter]

I modified my set-up and proceeded very carefully to cut the 4 mortises.

Everything lined up perfectly.

I think I'll use the Domino 500 to cut the upper mortises and the Domino 700 to cut the lower mortises. That way, I don't have to reset the fence and risk losing the correct setting.

Thanks for all the suggestions.

 

[jacko9]

I modified my set-up and proceeded very carefully to cut the 4 mortises.

Everything lined up perfectly.

I think I'll use the Domino 500 to cut the upper mortises and the Domino 700 to cut the lower mortises. That way, I don't have to reset the fence and risk losing the correct setting.

Thanks for all the suggestions.

Using both of your Dominos is a good solution.  I assume that you cut all of your upper mortises before resetting the fence to do the lower mortises, correct?  When confronted with moving the fence in this kind of situation I sometimes make spare parts at the first setting before I move the fence (just in case something goes sideways).

Jack

 

[Stoli]

Another approach would be to set the fence for the lower setting, and create a shim of the appropriate thickness that goes between the top of the workpiece and the fence to provide the desired offset.  No need for a second domino, but if you have an extra, ...

 

[NiteWalkerGR]

Another approach would be to set the fence for the lower setting, and create a shim of the appropriate thickness that goes between the top of the workpiece and the fence to provide the desired offset.  No need for a second domino, but if you have an extra, ...

That's exactly how doug stowe demonstrated attaching cabinet sides to the top and bottom using a biscuit joiner (different tool, but same concept) in his making small cabinets dvd and book.
That's the same way I'd do it; no setting change so less chance of something mis-aligning.

 

[Birdhunter]

These are all excellent suggestions.

I decided to build a prototype out of premium pine to both preview how the bench would look, but also to see what techniques work and what techniques don't work.

The actual benches will be of Ipe (Ironwood). It's way too expensive to waste.