A friend had a shop make him a dining table – I’m in the Middle East so hardware to extend the top for the leaf was not available. The shop constructed the extension mechanism using rails joined with a sliding dovetail. Now he notes that after a few weeks with the leaf in, the top binds when he takes the leaf out and he tries to close it up. He got it closed using some bar soap to lubricate the rails. Not sure what wood the rails are made from, table top is teak, but they might have used miranti for the non-visible parts.
Is this something that will be a continual problem? Should he sand the rails a bit to loosen them up? One additional bit of info – he is moving to Houston soon, so will be in that climate.
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I've never built table extension rails, so the muffled sound you hear is me talking through my hat. ;-)
The material used in the rails, I would think, needs to be as dimensionally stable as possible. And, the type of joint needs to allow free movement, while providing vertical support. The sliding dovetail might not have been the best choice, unless it's large and quite loose. But, loose defeats the purpose and function. A sliding T-slot sort of structure might be better - especially with him moving to Houston, which tends to be quite humid.
June through August in Houston is very hot and humid, often with regular afternoon thunderstorms.
I would say do nothing until your friend moves. I live in Chicago and.. June through August in Chicago is very hot and humid, sometimes with regular afternoon thunderstorms.
I have purchased and made my own sliding dovetails for large dining tables. As I recall the purchased ones were white Oak and the ones I have made were made of white Ash. The dovetails have a close but not tight fit and I lubricate the wood with common paraffin wax. I do not think that the purchased ones were quarter sawn wood. I do not remember. I use QS wood for mine.
Is it possible that too few sections were used for the span? If the span is long they need to be very substantial. Teak is very heavy! Also, I really do not know what the limits are for sections required as to span and weight of the table.
Maybe a search on the net would give you a better idea. Look for commercial wooden ones and see what they do for different spans? The smoothest operating ones I have made were sections of wood using Accuride drawer slides (heavy duty ones) fitted into wood 'carriers' that had a channel cut to fit the two halves with some space inbetween so they could move apart freely.
Do not forget about where a large and heavy table is placed. Is it on a thick rug with thick padding? Is the floor level? Twist in the table from less than ideal footing could be the cause. Think about.. The table 'sinks' into the rug and padding for a long period of time and sinks into the rug.. It likes where it 'fits'... THEN.. somebody opens the table and it now sits on top (sort of) the rug and pad at a different level!
Just me.... I would say... Nothing wrong with using sliding dovetails for a table. They have been used for many, many years.
At work our meeting table is built like this. Hunidity varies 30 - 90%. Maybe less inside but we only switch on the airconditioning when the room is to be used, average once weekly.
The table has survived several years. I would do nothing apart from waxing the runners until (if) the problem became drastic.
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