DanielOB said:
The plan has been changed, thanks to you guys:
- Parts under compression are 2x4 PINE no-treated (like legs)
- Parts under bending are TWO-plywood strips, 3/4" each, connected into one beam 1.5" thick x 4" height, by glue and screws (like a beam under doors 60" long ).
Hope this plan is better.
Thanks
I thought - and I believe others did as well - that you were using pine for the actual countertop. Hence my/our responses.
Pressure treated pine would be fine for the legs. In fact, I'd recommend it if it is going to be directly touching concrete. And a pine support structure is fine as well.
Now that we've got that sorted out, I'll try to answer your question. Pine from the big-box stores is notorious for being 'propeller wood'. If you have time, I would try to dry the wood down to about 8% MC before you build with it. If it goes squirrelly on you, don't use it. I know that sounds simple, but getting the bending/twisting out of the way up front just makes sense - and you really can't straighten it out later. If it's twisted, cupped, or bowed, it'll be that way forever (unless you machine it back to square, which would remove material so you'd no long have a 2x4 or whatever.
You can mitigate some movement by pairing boards, i.e. glueing the faces together with the grains placed opposite of each other. That way any stress created in one board is hopefully canceled ou by the same stress created in the other board. Hope that makes sense?
Once you have it READY to assemble, I'd either paint it with polyurethane enamel, or use a polyurethane clear finish if you like. The reason I would finish it completely at this point is that you can finish all of the cuts, ends, and sides...which is important to keep the wood stable. And polyurethane is TOUGH stuff - it'll keep the moisture content very stable as it won't easily allow moisture IN or OUT of the wood.
Hope this all makes sense and is helpful?