Gluing up wide boards

[Dave Novak]

Working on a 42" round table for my folks' christmas present. Red Oak (per their request, I'm not a fan) 6/4 stock. I can glue up the top in 4 pieces; 2 - 14" and 2" - 10". I'm getting concerned however about the width of the stock and cupping over time. Would you guys rip these down the middle and flip one half to reduce the chance of the top bowing over time? I have no idea what the moisture content is; don't have a meter. Thanks in advance for your thoughts/advice.

[Jim Becker]

Nope...I'd pretty much never rip wide boards in search of "stability". Show surfaces for me always have to display the best color and figure. In fact, I try to match things up as best as possible to make it look like one very, very wide board if at all possible! Your table top will not cup if you properly support it on the underside, too. Always build to accomodate wood movement...

[Dave Novak]

Thanks Jim, I really didn't want to rip those boards.

[Don Stephan]

Even ten years ago more people felt wide boards had to be ripped and growth ring orientation alternated. Today not so much. But I would suggest it is important to measure the current moisture content before proceeding, unless you are confident the moisture content is close to where it will be in your parents' house. And after completing the build, I'd suggest at least one coat of finish on all surfaces.

[Stephen Cherry]

If you look at how tables are put together, the apron is there to hold it flat. I would rather have a big gentle wave than ripples, the apron is better able to hold that flat.

[scott vroom]

+1 what Jim said

[Sam Murdoch]

If you look at how tables are put together, the apron is there to hold it flat. I would rather have a big gentle wave than ripples, the apron is better able to hold that flat.

Exactly right. Though I sometimes rip wide boards so that I can face joint them. Not really necessary with 4' stock that is pretty flat to start with and then depending on the grain you can often reglue with invisible seams. Lots of variables but generally I agree with the above comments.

[Sam Layton]

Dave,

I agree with the others, not to cut the wide boards, and secure it to the apron to allow for movement. The one thing I would add, depending on design, I like breadboard ends on tables. It helps keep things flat, and looks good. In addition, I like to use a reverse glue joint bit for the joints of my boards. For me, it makes a very flat panel/table top, etc.

Sam

[Jim Becker]

Sam...breadboard ends can indeed be a helpful solution for a rectangular table, but the OP's is going to be round. :D

For those of you mentioning aprons, there are other techniques that can be used to help keep a large surface flat during wood movement where an apron isn't used or even practical. In the OP's case, the fact that he's using 6/4 material bodes well as has more mass to work with, too.

[Bruce Wrenn]

One word of caution on glue joints. Because glue makes wood swell due to moisture pick up, I would wait at least one week to scrape and sand top after glue up. Whats really cute is when you use biscutts and sand the next day. Later, you have these little depressions where the biscutts are, because wood dried out and shrunk.

[Craig D Peltier]

I have a round table I purchased in Costa Rica, its about 24 inches across. Under the top is a square board that's almost same size maybe 20 inches square. The table traveled from there, to me in California for about 5 years then to Seattle for last 6. It warped so bad even with that huge support underneath. People have looked at that are woodworkers and said wow it doesn't look like it could do that. So you never know. The wood is mahogany.

[Sam Murdoch]

Craig, what you describe is exactly what I would expect. Wood needs to be allowed to move as it expands and shrinks with relative humidity across the grain. Tying one group of boards down to another with screws or nails or glue with no allowance for expansion and contraction is just a self fulfilling wood working failure.

Regarding depressions over biscuit slots - yes that can happen if the biscuits are set to close to the surface of the boards. Typically 5/16" or more from the finished face is a good depth. I have used biscuits for aligning boards prior to glue up with excellent results for too many projects to remember. The one time I saw biscuit dimples is on my own coffee table top. I glued some beautiful jatoba boards for a top to be set on a piano bench and started experimenting with the finish - stain and clear coat. By the time I was satisfied with the finish I had gone through the wide belt sander with this top and took it down from 1" thick to 13/16" - yes the biscuits telegraphed through (in the right light). The finish was excellent though :D.

[Sam Layton]

Jim,

You are correct, I missed the ROUND part when I read the post.

Sam

[Jim Becker]

Craig, I'll also add that it's very likely that the table you describe was made with material that wasn't moisture stable, either. Then fastening a big, thick piece of wood under it didn't allow proper seasonal movement. Even something very thick can warp under those circumstances.