Why is this happening to an oak table?

[yartin]

the only other choice is the edge is drooping but theres not enough overhang to make that happen easily ???
so the only gap is 1mm on top??
any gap between the side block and the cross beam or indeed a shadow under the area off the block to suggest its moved up

There are 6 blocks, 3 on each side and 2 long blocks for each end, I can insert credit in each easily except one middle, means anything?

 

[big-all]

ok try a different tack
insert the extension leaf and apart from the point it goes through the table base mark on any cross timbers it touches with chalk
then follow those timbers and note any gaps between any timbers en route to the side rails and try and see iff you have any loosness or movement by perhaps grabbing the cross rail centrally and wiggle it quite heavily

 

[yartin]

Tried nothing wiggling, very solid.

The 2 side rails assembly have failed, don't know why both same time. I took all screws of the 6 side blocks and 2 end blocks and still no movement of any part, even the blocks are fixed on somehow?
Only one thing if it's that, whether jointing biscuits between side rails and front rails have failed?

 

[big-all]

will usually be dowels or a large glue area caused by the mating surfaces having grooves and mouldings increasing the contact area and because they are male and femail they interlock but in this instance is will be no more than a short stub tennon [to stop it showing at the face]to match the groove for the boards to fit into

 

[yartin]

I guess the stub tennons are glued or just push fit?
would be easy to disassemble? And rebuild?

 

[big-all]

not that easy i am afraid glue seals the surface and into the grain hence its strength
the problem you now have is even iff you get a good clean surface you have the grain sealed
now you will get some bonding, it will be fully surface on old glue so perhaps only 50-80% as good so you need to stop the load putting so much weight in the wrong place to give it a chance to last

any one who has cleaned out and re glued a loose chair will tell you it wont last long

somthing like 10mm 4 inch stainless steel rods may help??
https://www.ebay.co.uk/itm/323175383233?var=512261555838&hash=item4b3ec100c1:g:7yQAAOSwNTVfZg-x

 

[yartin]

whats the use of steel rods??

 

[big-all]

to remake the joints on the table top to stop the the sides pivoting up
but mind and use stainless as the tannin in the oak will rot steel and cause black stains including streaks if water gets spilled

 

[yartin]

to remake the joints on the table top to stop the the sides pivoting up

metal dowels?

 

[big-all]

metal dowels?

yes indeed there must be a heck off a lot off strain to break a glue bond so now you can not replicate the original strength you need to go ott rather than a bit stronger with wood dowels that will probably fail where as 10mm or even 8mm [at little saving ] will do the job as near to as strong as you can get without added external support

and shop around you may get stainless at a far cheaper price that was a fully random link

 

[pcaouolte]

It looks to me that the slats in the centre of the table have absorbed some moisture from the atmosphere and expanded across their width. This expansion has pushed the side rails away from the table. As the centre slats are thinner than the side rails this expansion has pushed mainly against the top of the side rails causing them to sag downwards.

 

[yartin]

It looks to me that the slats in the centre of the table have absorbed some moisture from the atmosphere and expanded across their width. This expansion has pushed the side rails away from the table. As the centre slats are thinner than the side rails this expansion has pushed mainly against the top of the side rails causing them to sag downwards.

Suggestions?

 

[big-all]

when you dry fit it back together iff the panels are holding the side rails appart by more than say 3mm then you would need to shave off the slats/top not the rails