Affixing a chair seat?

[JonathanJung]

Float-mount a seat on a chair, or glue it down permanently?

I've been attaching the seats to my chairs similar to a tabletop, see picture. However, it's not as clean looking and the screws can't grab very much wood, because of the deep seat scoop. The main thing though is that it doesn't suck the seat down tight to the frame, as tight as I'd like. There is only 3/8 - 1/2" screw penetration so it's risky to really crank it down. Using the Wood Web shrinkage calculator, rift/qtr sawn walnut at 14" wide (the width of contact between seat and frame) has minimal movement, around 1/8". I'd rather be able to set a couple dominos and glue the seat down.

Does anyone know if glueing the seat down would be safe enough against splitting?

I've known breadboard ends on tabletops to not be an issue before. I realise that my customer's home humidity control will have an effect, so I calculated for an 8-12% MC variance.

 

[ChuckM]

1/8" variance is too much for my comfort zone, unless the piece stays in a humidity controlled environment for good. (Many wood movement problems appear after someone moves from one place to another.)

"I've known breadboard ends on tabletops to not be an issue before."

Not familiar with your exact construction method and size of the piece, I've seen my share of breadboard end splits. The attached image is one of the many from the internet. More examples are found by furniture restorers.

 

[Birdhunter]

Have you considered using Z clamps?

 

[JonathanJung]

Have you considered using Z clamps?

Same thing as tabletop clips? Yeah, does the same thing as a Domino.

I think I'll try screwing through the base. Will oversize the hole and counterbore to allow for movement. I don't want holes though, since I imagine customers like to grab the curves under the seat.

1/8" variance is too much for my comfort zone, unless the piece stays in a humidity controlled environment for good. (Many wood movement problems appear after someone moves from one place to another.)

"I've known breadboard ends on tabletops to not be an issue before."

Not familiar with your exact construction method and size of the piece, I've seen my share of breadboard end splits. The attached image is one of the many from the internet. More examples are found by furniture restorers.

That split looks like someone sat on the breadboard and snapped it.

 

[bcrawley]

When I grab under a seat it is typically at the sides. If that is true for you, you could keep the holes to the front and back; do your domino thing on the sides if it seems you need that too.

 

[ChuckM]

Snip.

That split looks like someone sat on the breadboard and snapped it.

I suspect that the whole breadboard end was glued to the top, with no allowance for wood movement whatsoever.

Top splits are pretty common in older pieces, too. I fixed a table top for someone; the piece was made in 1957 in England as part of a high school shop class (called secondary school there), and brought to Canada when the family moved over. The top was screwed to the aprons with no elongated holes drilled. The oak table is about 22" wide, in line with the smaller houses built in those days.

For a 14 or 15-year-old kid to build such a table with bridle and M&T joinery, it said a lot about the old British education system. (The joints also came apart with the passage of time.)