Slab Attachment

[Kevin Stockwell]

I have a 42" x 84" x 2" thick slab tabletop made of parota wood. I have a conventional tavern table base with aprons and stretchers that is made of walnut. I plan to use buttons to attach them, but have a few questions first.

The wood is fairly soft, "Like redwood heartwood" as somone has described it, and not great at holding screws. So I ordered some heavy duty 3/4" long threaded inserts from McMaster-Carr http://www.mcmaster.com/#90192a124/=9qdei6 (http://www.mcmaster.com/#90192a124/=9qdei6) for use with 1/4-20 capscrews that I have from my speaker-building projects. I was thinking of adding epoxy to the inserts before screwing them into the wood. What do you think?

I was going to use the buttons in the aprons to account for wood movement. Here is the question on that---if this slab is 42" wide, how much "growth" in width do I need to account for? I ask because my aprons are 1" thick walnut, in which I will route out a dado. Can i safely put a 1/2" deep dado in a 1" thick apron? If I do that, and have the lip of my button 1/4" in the dado, am I limiting myself to 1/2" total movement in width before the button bottoms out in the dado?

Any other suggestions or alternatives welcome.

Thanks

[Frank Drew]

Kevin

I don't know that wood, but I think 1/2" movement with the seasons isn't at all unrealistic to expect. For some reason, I once made a 6 foot sycamore utility table top with the grain running the short direction, and that top definitely moved about a full inch its first year.

I don't think 1/2" deep grooves will weaken your aprons. You could also slot the screw holes in the buttons to give them a little more room to play, in addition to however much they can move in the grooves.

[Jan Bianchi]

If you know the current moisture content of the walnut and what you expect the moisture content to be when it is acclimated to the enviroment in your house, or the relative humidity now and the relative humdity where you will keep it, you can figure this out using The Shrinkulator http://www.woodbin.com/calcs/shrinkulator.htm

That's really my question I asked in a post a little earlier than yours today. I'm having a little difficulty figuring out which relative humidity reading to apply, or what the final moisture content might be given conditions here, but you might look at it. If you figure it out, would you take a try at answering my questions on my post below.

[Kevin Stockwell]

I looked at that, but my wood is not listed. Sorry.

[Kevin Stockwell]

Kevin


I don't think 1/2" deep grooves will weaken your aprons. You could also slot the screw holes in the buttons to give them a little more room to play, in addition to however much they can move in the grooves.


Good idea--a bit of slot to the button may give me some breathing room.
Thanks