To smile or to frown - slab orientation

[Shane Jimerfield]

I'm building a new work bench to go with my new Twin Turbo vises. It's gonna be a split top Roubo style.

I picked up two 10" x 4" slabs of reclaimed old growth SYP. The mill planed them flat for me, so nice.

I'm wondering about grain orientation. They are tight grained, old and dry, so I'm not expecting them to move. Would you put the center down or up?

Aesthetically I like the frown, though I won't see the ends much, because the grain looks best.

 

[..Kev]

Well, they're going to move!  They always do.

Are you gluing them together or doing a split top?  If you're gluing, I would consider alternating them to help avoid cupping.

[Shane Jimerfield]

Yes, true that, but I don't expect much movement due to the condition of the wood, and climate control of the shop.

Split top.

[..Kev]

16 minutes ago, Shane Jimerfield said:

Yes, true that, but I don't expect much movement due to the condition of the wood, and climate control of the shop.

Split top.

I wouldn't worry about direction with a split top.  

Flatness is a very open debate when it comes to bench tops.  Even though I have a torsion box assembly table, I don't really think that it's imperative that a bench top be dead flat.  Those 2 slabs are going to move with seasonal changes but, hopefully evenly across the grain and not causing you any issues.

[Chestnut]

If the frown looks the best go with that. I think it could be heavily debated which is best and no real answer would be had.

[drzaius]

1 hour ago, Chestnut said:

I think it could be heavily debated which is best and no real answer would be had.

Ain't that the truth. About the only sure thing is that if the lumber is wet, the outer rings will shrink more than the inner rings. So a wet frowning board will go concave on top as it dries, the opposite for a smiley board. But you shouldn't be using wet lumber anyway and for stable, dry lumber I don't concern myself with it; I pick the side with the best grain.

[Chestnut]

This reminds me I have to flatten my old workbench... .

 

[Mark J]

Well, I'll throw this thought out there.  If the boards were to move which would you rather flatten with a hand plane?  The cupped frown or crowned smile?

Although looking at the grain, since the outer rings are not complete, I don't think any theoretical movement would be that simple.  

[Tpt life]

Concave up, a board might sit ok. Convex up a board will rock. That’s of limited value as thinner boards will flex to the profile. Just two cents of thinking. 

[Ronn W]

Whatever you decide, you're goin to have a great looking bench.