The table top. I’m looking for thoughts should anyone offer them up…
So on paper, I drew up this outdoor table to hold my grill. I purposefully used the same joinery techniques that I’m using for my indoor living room table (yet to be finished); practice the through tenons to attach the tabletop on an outdoor piece prior to doing it on the real thing (the indoor piece).
The goal of this project (from its inception): Build a simple outdoor table to hold my grill (to prevent it from tipping) using bomb-proof joinery. I don’t care if it has flaws or what type of wood it’s made of (so long as it’s strong)… and it’s a requirement to keep the price under $1000. Furthermore, I don’t necessarily care if the top is flat, so long as it holds my beer while I cook. Lastly, the lifespan of the table is the lifespan of the grill; once I get rid of the grill, I’ll have no use for a table with a big hole in the top. I put the lifespan in the 15-20 year timeframe.
So I have a co-worker that spent 3 months (three!!!) apprenticing under David Charlesworth, and it took a point-out from him to catch a major flaw that I completely missed in the designing of the table. Take a look:
Wood moves. Once he pointed that out, I looked it up: with seasonal movement, the front-to-back portion of the table top will contract and expand up to ¼” either direction (maybe even more). Over time (maybe a year, maybe ten years), the tabletop will either crack, warp, or pull the upper fox-wedged tenons slightly out of their socket, weakening the joint. Fortunately, the living room table I designed this thing after (at right) has a different top (it’s not one solid piece of wood) that allows through-tenons to secure the table top into place without the worry of movement.
What to do, what to do…
Here are the facts:
- the white oak top has been sitting outside, air drying, for a few years. I’m pretty sure it’s acclimated to the moisture content where I live now. So for now, this should minimize the movement. (Who’s to say when I move in a few years how much the moisture content of the new location will affect it)
- I plan on applying some type of liberal finish on the top to slow the movement down. I know, I know; I can’t stop it… but maybe slowing it has the potential to prolong against any catastrophic failures?
So what do I do? Here are the options I can think of:
- Build to fail (I guess this is the best way to put it): proceed as planned knowing that the top will warp or weaken the upper joints that oppose the grain movement. Like I said, this is an outdoor table whose lifespan will be that of the grill. Again, it just has to be flat enough to hold a beer successfully while grilling. I guess this way I can see wood movement in action (kinda like the experiments Brian was running over at Toolerable) and learn through failure to not plan like that again.
- Cut off the tenons that protrude from the base and find a movement-safe way to attach the top to the base. Things I’ve seen are wooden “buttons” or metal figure-8 braces. I hate to say it though: I really kinda liked the way through-tenons looked, and part of the reason I designed it that way was to give it a shot on the outdoor table before I do it on the indoor table (practice, if you will).
- Rip the top down the center (where I initially book-matched it together!!) and attach it to the base as 2 pieces, still using the the four through-tenons as points of attachment. It will allow the top to expand and contract towards the middle of the table. A lift grip centered on the sides of the table will obviously lift the tabletop from the base and stress the through-tenons. Therefore, any lifting must be done via the front and back of the table (rather than the sides). I dunno if I like the idea (visually) of having it split down the middle.
My co-worker did offer up that it can be ripped at an angle to attempt to hide the gap somewhat:
I’d be curious to hear what anyone has to say on how I should proceed… especially if you’ve had experience or horror stories with wood movement…