Tabletop Expansion Question

[Slim]

I am building a small side table and have a question about the top.

As you can see from this photo, the top is going to wrap around the top of the legs. (I haven't glued on the side pieces yet)

I am worried about the top expanding, pushing out on the legs and causing the rail joints to fail.

Do you think I need to leave an expansion gap around the legs? If so how much? It is only a small table. The part of the top in the photo is only 370mm wide. Is the expansion over this small distance going to be significant?

Many thanks.

 

[Wanlock Dod]

Hi Simon,

There is a calculator on the web somewhere which will calculate the expansion (on the same site as the sagulator?) for a variety of (mostly American) timber species. In my limited experience, I think that if the timber is seasoned and equilibrated with the air conditions (relative humidity) in its final home there will probably be relatively little movement (due to minimal change in the relative humidity in a centrally heated house). I made a table with breadboard ends a couple of years ago and have observed very little movement of edges of the top relative to the ends of the cross pieces (I would estimate less than 6 mm total over an 80 cm top), although I expect that the relative humidity is usually around 55%, and rarely outwith 45 to 65%.

So, I don't think that you would need much of a gap, maybe 1 mm each side would be enough (provided that the timber is already at equilibrium with it's final resting place) although you might need to be able to allow for movement relative to the rail.

Cheers,

Dod :?

 

[wizer]

I would build a gap into it as a design 'feature' and make it about 4mm all round.

 

[Slim]

Wizer, I think that is what i'll do.

Cheers Fellas.

 

[wizer]

no worries, you are obliged to post more pictures as and when progress occurs