Domino and glue up of purpleheart/maple desk top

[fignewton]

Howdy everybody.  Working on a desk top for a guy, and I have 6 boards of PH in various widths.  I’m going to cut strips of maple to go between each set of boards to give a striped effect.  The strips will be about .6-.75 inches wide.
My question is how best to do the dominoes?  One way would be to try to glue the strip to the board, then cut the domino through the both.  But that way, I don’t have the domino to locate the strip in reference to the board. 
Another way would be to try to clamp the strip to the board, then domino through both, then glue them together
Or, use short 4mm dominoes and use them to glue up the strip, marking the board where they are so that when I join two boards, I don’t try to domino over the small ones.
Hmmm, and another thought.  I should prob make my marks and cut the dominoes deep in the maple before cutting my strips off on the tablesaw.

Whadya think, team?  Thanks

 

[ChuckM]

You didn't say how wide and long those boards are.

If they're not really that long, I wouldn't even use the dominoes. I'd just glue them up as sub-assemblies and then, after they're cured, glue the subs together. You may have or need some kind of a panel glue-up system for the final glue-up to ensure a flat top. See a mock-up below.

 

[fignewton]

final length will be 63 and total width 31 inches

 

[rmhinden]

Sounds like it equivalent to putting solid edging on a cabinet. 

I think if I was doing this, I would make the maple a little thicker than the thickness of the purple heart,  glue the maple to the purple heart without dominos, level the maple by running them through the planer (or use a router or hand plane depending what you have available).  Then use the domino to join the resulting boards.

Bob

 

[ChuckM]

final length will be 63 and total width 31 inches

If the stock is straight and flat, and you have a reliable panel glue-up system, for such a width, just use glue and clamps in a sub-assembly approach (2 subs or so). 

If your stock is less than desirable, use dominoes sparingly for alignment, not for structural strength as it is face grain to face grain, between the sub-assembilies. Or, use clamping cauls -- and that's how others who have no domino joiners will handle such a task.

 

[Birdhunter]

Suggest you swab out the mortises with alcohol or paint thinner before gluing in the tenons.

 

[fignewton]

Suggest you swab out the mortises with alcohol or paint thinner before gluing in the tenons.

Why? Is there something unique about the PH?  I haven’t seen anything about it when researching using and finishing it.

 

[junk731]

Did your research indicate that Purple Heart turns to a dark brown colour from the purple with age and exposure to UV no matter what clear finish you use. Also gluing can be problematic.
https://www.wood-database.com/wood-articles/gluing-oily-tropical-hardwoods/

 

[fignewton]

wow, thanks for that article.  Knew about the color change, but didn’t see anything before about gluing. I noticed that this is definitely oily textured wood.  I’ll look more into the poly glue use too.  Just got the plans and watched the video for The Wood Whisperer’s big green egg table, which I’ll make next for a friend.  He used the poly for the sapele he used. 

 

[Birdhunter]

I've used TiteBond III with oily exotic woods, but only after using naphtha in the mortises immediately before gluing in the tenons. I've also used two-part expoxy and I can't see any difference except the epoxy is fussy to work with.

I would strongly suggest trying whatever finish you plan to use on some scrap. My experience is that most finishes just sit on top of the oily wood's surface and don't dry. They just stay gummy.

There are some real experts on this forum. You could post your question in the Finishing & Painting section.

 

[junk731]

Just another hint if you are going clean wood before glueup use something like Acetone for fast evaporation and no oily residue like naptha or mineral spirits. Also stay away from that titebond crap, too many potential issues. I prefer a good epoxy for longevity especially using exotic woods.