Trestle desk top -- breadboard edge to conceal uneven board thickness?

[Ken Cohen]

Hi --

A crazy idea dawned on me while milling up boards for a trestle desktop (helped immensely by this discussion (http://sawmillcreek.org/showthread.php?t=152763).

As a quick reminder, I'm a desktop rookie, bringing three curly maple boards together to form a ~28x70 top. The far side will always face the wall.

Moving patiently, the milling has proceeded well and all the boards are now rough planed and flat enough. My goal is as thick a top as possible. Turns out that the rough 4/4 stock yielded a hair under an inch in the front board and 13/16 in the others.

While I can live with a 3/4+ thickness, I wondered whether I can use the ~4/4 front board to create the illusion of a full 4/4 top. I imagine two pieces of additional work: adding 4/4 breadboard ends (I have the extra stock form the cutoff) and routing in a flat "channel" for the trestles on the underside.

Before I contemplate whether this is worth the effort, I wonder whether this is a workable approach, will it yield the appearance I am seeking, or is there another approach I have missed? Also, candid feedback that extra 1/4 is unnecessary is fine.

Thanks for the advice.

Ken

[Chris Padilla]

Your approach sounds workable. You will just have extra effort to put into the top to deal with an uneven bottom but as long as you've thought it through, I say go for it! You will learn a lot!

Think ahead a bit and do a dry run or two for the top glue-up. Do you want the flat side up or down for gluing? I would say up so you can ensure it is as flat as possible but then you'll have to shim the bottom. I would say down so that worries of shimming aren't there but then you can see the top during the glue-up to make sure you have it flat. Dry runs!!

[glenn bradley]

I see no problem with that. Cut you tongues centered on the thinner stock and offset on the 4/4 stock and voila. If the table were to be seen from both long sides you could split the 4/4 long board and use the pieces as the outside boards of your glue-up; presto, the table looks thicker from all sides ;-)

+1 on Chris' recommendation for dry runs. Dress rehearsals for a glue up have saved me more than once.

[Howard Acheson]

Yes, what you propose is perfectly fine.

Here is another point. If the same edge will always be toward the wall and you end up doing breadboard ends, you can greatly improve the final appearence. You would do this by forcing all the expansion/contraction overlap to the edge of the table that will face the wall. In other words, instead of fixing the breadboard in the center, fix the front of edge of the breadboard to the front edge of the table. Make the center of the breadboard and the back edge movable. Use a dowel coming up from the bottom and a slot for the center of the panel and the back of the panel.

Using this approach, all the movement mismatch will be at the wall where it will be much less noticable. The front will always remain fixed to the front edge of the completed panel.

[david brum]

I've done exactly what you propose. It worked fine; in fact, I even glued an extra strip to the bottom of the outside board to make it look even thicker. Howard is absolutely right-on with his advice about fixing the bread board end on the outside edge of the good side. I did a desk top out of madrona, fixed in the middle, and had 1/8" of bread board sticking out into space within 2 weeks. I still kick myself for not thinking to fix it on the good side.

[Ken Cohen]

Thanks for the reaction and very helpful advice. My takeaway:

1. Proposed technique is fine

2. Sweat the dry fit stage and get it right

3. Pin the breadboard to the front edge of the first board (great idea).

Question: In an earlier post, it was suggested that biscuits (unglued) are counterproductive as an alignment aid in a trestle top glue-up. Given the new situation, might biscuits help to align the intended parallel top surface?

Thanks again.

Ken

[Chris Padilla]

Biscuits are great for alignment purposes but can also be wonderful for MISalignment purposes. Just take care in cutting the slots to ensure the references are exactly the same and you should be fine.

Pre-sort your biscuits ahead of time to find the goldilocks (fits just right) ones and don't bother gluing the biscuits but no biggie if they get some on them...just don't focus or waste time ensuring they are glued well.

Cut the biscuit slot depth ~1/32 - 1/16" deeper than half the biscuit's seating depth. A good trick is to cut on some scrap, insert biscuit...mark line to indicated seating depth...pull the biscuit out and turn it around...reinsert...mark again. Just remember which mark is which. :)