How much expansion/contraction of a 85cm wide top?

[Deadeye]

Top is 48mm thick pear wood and I need to allow some movement slots for the fixings. Is there an online calculator?

Thanks!

 

[Sachakins]

https://kmtools.com/pages/wood-movement-calculator

 

[niall Y]

If you are using buttons they are quite forgiving and can be repositioned My gut feeling would be to allow for 12mm of movement. The slots in stretcher plates allow for 18mm.

 

[Deadeye]

https://kmtools.com/pages/wood-movement-calculator

Thanks - I guess if I go for Apple it'll be similar

 

[Deadeye]

If you are using buttons they are quite forgiving and can be repositioned My gut feeling would be to allow for 12mm of movement. The slots in stretcher plates allow for 18mm.

Thanks - I'm using threaded inserts. Sounds like 2cm...which is what the calculator suggests

 

[Jacob]

Top is 48mm thick pear wood and I need to allow some movement slots for the fixings. Is there an online calculator?

Thanks!

48mm is a heavy and thick table top and unless it is very dry and stable then cupping could be more of an issue.
I've done a few kitchen style tables with sycamore tops and 20 to 25mm still makes a hefty table.
They seem to move max 5mm across the top, as shown by breadboard ends, but it all depends on how dry to start with.
It's a good idea to look at old furniture. A mahogany top even on a big classy table is likely to be nearer to 18mm.