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How to design a solid wood (no plywood) top for a trunk?

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Forum topic by wdwrkr posted 01-17-2012 02:59 PM 2017 views 0 times favorited 11 replies Add to Favorites Watch
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wdwrkr

26 posts in 2466 days


01-17-2012 02:59 PM

It seems simple enough – build me a box, she says.

I’ve been asked by a client to make a chest approx 34”W x 21”H x 24”D. I am making this chest to replace one that has been badly damaged by differential movement – joints have failed and boards have split.
Since this is to be a piece to hand down, and I want to avoid any potential delamination issues if she leaves a glass on the top (sweating damage), I want to make it of solid wood – no plywood.

The question is, how do you account for wood movement in a solid top panel as it will be constrained by the frame around it?

I know I can make one or more floating panels, and to reproduce the existing chest, a single panel would certainly work. However, as a matter of curiosity (and especially for the next project), I would like to have a different solution.

Thanks for any ideas/suggestions!


11 replies so far

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Jim Finn

2413 posts in 2387 days


#1 posted 01-17-2012 05:19 PM

I do this using 1 1/2” Slats trapped in grooves all around like this:

-- "You may have your PHD but I have my GED and my DD 214"

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MichaelAgate

398 posts in 1789 days


#2 posted 01-17-2012 05:49 PM

Sweet – Nice craftsmanship.

-- Michael and Matthew

View CharlieM1958's profile

CharlieM1958

16242 posts in 3683 days


#3 posted 01-17-2012 06:24 PM

As far as I know, you really can’t put a frame around a solid wood top panel without running the risk of damage from wood movement.

You could either attach the top on top of the frame with tabletop connectors that allow for movement, or you could let the top panel float inside dados in the frame, the same way a frame-and-panel cabinet door is made.

-- Charlie M. "Woodworking - patience = firewood"

View David Kirtley's profile

David Kirtley

1286 posts in 2463 days


#4 posted 01-17-2012 07:43 PM

About the only way to control this with solid wood is to use frame and panel construction. It will not totally eliminate it but it will bring it to a more manageable level. Wood moves. Nothing to be done to prevent it.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

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DrDirt

4169 posts in 3207 days


#5 posted 01-17-2012 08:29 PM

Wood movement is going to be primarily cross grain – our boards don’t get longer with humidity to an appreciable degree.
As others have mentioned – you need the panel to float so e.g. in your photo – that gap in the top panel around the perimeter would be a bit larger and the top would have a tongue around it that sat in the dado as Charlie has described.

In any case – I would not be concerned about “sweating”if she put a piece of glass on the top. I would however place silicone feet on the glass to both keep if from sliding easily and keep it from gluing itself to the surface if the finish isn’t really well cured before the glass is placed.

If it really has to be tightly mitred etc. Then Ply becomes the only real option. The glues used these days ensures it will not delaminate like the stuff during WWII and into the 50’s did. But you cannot buy it at the BORG.

-- 'Political correctness is fascism pretending to be manners' ~George Carlin

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wdwrkr

26 posts in 2466 days


#6 posted 01-18-2012 03:51 AM

Thanks all for the help!

It is as I imagined – the top must be frame and panel.
BTW, my concern about glass was attributable to a potential glass of iced tea left on the lid in August in Washington DC with a broken air conditioning system. I could see it condensing a pint of water out of the air and it lying there on my beautiful wood chest. :)

The problem is that I have seen examples of chests similar in design to my client’s red chest – photos provided by our brethren. Perhaps the explanation is that the photos are either of newly completed projects and they haven’t yet experienced the humidity swings associated with seasonal change, or they are constructed from plywood…which is more likely the reality.

Thank you again…

View CharlieM1958's profile

CharlieM1958

16242 posts in 3683 days


#7 posted 01-18-2012 05:30 AM

wdwrkr: With regard to your seeing other chests built like your clients…. Regional weather patterns can have a lot to do with it. Here in New Orleans, relative humidity remains uniformly high throughout the year. Even inside, whether my heater or my air conditioner is running, humidity will run about 50-55% year round, so seasonal wood movement is rarely an issue with my projects.

-- Charlie M. "Woodworking - patience = firewood"

View David Kirtley's profile

David Kirtley

1286 posts in 2463 days


#8 posted 01-18-2012 05:46 AM

Plywood is not inherently bad. It is just given a bad reputation by old technology and cheap plywood. High quality plywood is strong, light, stable, and many times waterproof. The down side is that you are not going to find it at your local big box store. Most specialty stores will have to special order it.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

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a1Jim

115202 posts in 3042 days


#9 posted 01-18-2012 06:26 AM

I have seen a couple examples of tops like that too.The had cracked tops too. Most blanket chest have either frame and panel or solid tops without frames or plywood.

-- http://artisticwoodstudio.com Custom furniture

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wdwrkr

26 posts in 2466 days


#10 posted 01-18-2012 02:35 PM

Good suggestion David. I’ll contact my wood supplier about cabinet-grade waterproof plywood to see what options there are and consider that solution path. Interestingly, and as an aside, he does sell waterproof MDF that he says a lot of cabinet makers are using. I do know his plywood prices often start at $100 a sheet and most are much more – amazing isn’t it?

You are absolutely right about there being so much poor quality stock around (Home Depot, Lowes, etc.). Their sheet stock delaminates, has voids in the veneered surface, has voids beneath the veneered surface, often isn’t flat, etc.

Thanks again all for your comments.

View David Kirtley's profile

David Kirtley

1286 posts in 2463 days


#11 posted 01-18-2012 03:32 PM

If you are looking at ply, marine grade hardwood ply is the ticket. They are usually okume or sapele. The sapele is a bit harder and the okume a bit softer and lighter. Baltic birch is pretty nice as well but not marine grade. A fair way to judge what is good and what sucks is the number of laminations. In 1/4 in ply, you should be up to 5 layers. They also have some fir that is marine grade as well. When they say waterproof, the tests that they are using is where they boil and dry the ply in cycles.

They do have some fair stuff at some lumber yards that is not pretty but tough. Usually labeled MDO. It is the stuff that they make street signs out of. It is good structurally but the faces usually have a composite facing.

I don’t really like using MDF but some of the high grade stuff is pretty solid. They use it for the base for some veneers because it is stable and there is no grain to telegraph through to the surface.

-- Woodworking shouldn't cost a fortune: http://lowbudgetwoodworker.blogspot.com/

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