Domino joinery dilemma for front entrance door

[thoffman]

I'm building a front entrance door approx 80" x 36" and 1 11/16" thick (about 43mm).  Door will have two 5.25" stiles and three rails: 8" 9" and 10". (two additional interior stiles and panels, but let's ignore that for this discussion).

I'm considering two different jointry scenarios to connect stiles to rails:

A) Double stacking 8mm.  So from top to bottom of the 44mm material:  9mm wood, 8mm domino, 8mm wood, 8mm domino, 10mm wood for a total of 43mm thickness. 

B) Single 14mm domino; 14mm wood, 14mm domino, 15mm wood. 

Scenario A comports with a posting from Greg Portland on 11/8/12, "Festool recommends no more than 1/3 the thickness of the wood for a single tenon. For stacked tenons, they recommend at least 1 domino thickness between tenons and to the edge of the wood. For side by side tenons they recommend at least 2 tenon thicknesses of spacing."

Both scenario A and B approximate the tenon comprising 1/3 of the thickness of the wood.

I'll figure out spacing between dominos.

Each domino would be 140mm long, so each mortice would be 70mm.

The wood I'm using was sold to me by a very reputable lumber dealer as "genuine mahogany."

Questions: 

Which joinitry scenario is better?  It seems to me that scenario A would provide better dimensional stability, but mahogany is supposed to be very stable.

Going with scenario A adds complexity with the double stacking getting everything to fit properly. 

Scenario B would be easier and faster.

Are there advantages to scenario A that would outweigh the complexity and time involved of A over the ease and speed of B?

Thoughts and comments would be most appreciated.

 

[Birdhunter]

This problem is outside my experience base, but I have done double stacked Dominos with my 500 before I bought my 700. I had to be ultra precise to get the pieces to go together. Just a tiny bit off and the pieces don’t mesh.

The good thing about Dominos is that you can cover up a mistake by glueing a Domino in the mortise and then saw it off flush. Then, recut.

 

[multiblades]

Go to the video at the bottom of the page, is about 12 minutes long and shows how to use the Domino to build an entrance door.http://www.thisiscarpentry.com/2012/03/16/festool-domino-xl-review/

 

[John Stevens]

My concern is that the 8mm won’t be deep enough.  I’d think you’d need max depth of the 14mm dominos to make the joints resist wracking.  Would appreciate hearing from folks who know.  I remember seeing some of our Scots and English FOGgers posting about door-making.

 

[RussellS]

He said both domino sizes, 8 and 14, would be 70mm deep in each piece of wood.  For strength, A is better.  More glue surface area.  And two 8mm is 16mm total of tenons.  Compared to the 14mm tenon.  So more tenon wood strength too.  I think either of your scenarios would result in an excellent door.  So doubt there is really much difference.  Maximum strength with A.  But both are strong enough.  So probably go with the easier B.

 

[TXFIVEO]

I just built an exterior door out of Douglas Fir 1-3/4” thick and used 14mm x 140mm dominoes. Just received the insulated glass unit to install it and do the glue up.  While I’m sure the Domino 500 is capable by stacking dominoes for the build the Domino 700 has made building interior and exterior doors a breeze. 

 

[fshanno]

I made a 32x80 pocket door with the little dominoes.  No problem there, it just has to hang!  It has two big panels which are chalkboard material.

My problem with doors is flattening the big boards.  I have to do the long ones and the wide ones by hand.  I'm miserable at trying to edge joint by hand.  I had my TS55 to do the edge jointing

 

[ear3]

I think either scenario would work well.  I have never build an entryway door, but I have built similarly sized frame and panel construction with dominoes.  The one advantage of stacking dominoes is that it helps cut down on the piece flexing/bowing under clamping pressure during glue up.  Generally speaking the 14mm domino is thick enough that it prevents this, and with well-placed cauls you can control it even further, but the two 8mm dominoes would rule out flexing almost entirely under the considerable clamping pressure one needs for this sort of construction.

I assume you are making your own dominoes or getting the uncut 8mm domino stock, as I don't believe Festool offers 140mm lengths in the 8mm. 

 

[sancho57]

If you already have a domino 500 I’d stack the dominos  and use a couple of  dowels