Campaign Trunk - advice on solid top

[Glynne]

This post could have gone under "Design" but it does have wider implications so....

I'm looking to build something like this for one of my grandsons: -

The question I have is around how do I construct the solid top? (as the lids often contain attachments, mirrors etc.)
I've made loads of boxes with "deep" lids but have always had an insert panel to allow for expansion and contraction but as you can see with this trunk and many other similar ones I've Googled, the top is solid all the way across.
Looking at some images for tool chests, a lot of these appear to be frame and panel construction with small expansion gaps on the top so I'm a bit stumped.
I'm not sure if it is of any relevance but most of theses type of chests are made from camphor wood, I'm planning on oak?
Any thoughts, advice would be appreciated.
Thanks for looking.

 

[bourbon]

Camphor wood is used in campaign chests to deter moths and the like. Make it in whatever you like.

 

[Racers]

Just because people make things the wrong way dosn't mean you should.
Frame and panel is the best way.

Pete

 

[woodbloke66]

In the Schwarz's book on 'Campaign Furniture' that I've just leafed through, he mentions on page 26 that tops and bottoms can sometimes (?) be 'found floating in a groove' and they can be reinforced with a centre muntin. However, if you don't want to do it that way, the safest option is thick, bandsawn veneers over a substantial substrate - Rob

 

[marcros]

do you have to make the brassware yourself or can you buy it somewhere?

 

[woodbloke66]

do you have to make the brassware yourself or can you buy it somewhere?

The best place I've found for this sort of stuff is HE Savill - Rob

 

[Glynne]

Thanks for the replies guys.
Pete - I can manage to do it the wrong way even when I know what the right way is! I might be at the Derbyshire Woodland Festival next weekend if you want to treat me to that cake?
Rob - I did see the book when I was having a quick Google but this is probably the only campaign piece I’m likely to make. Besides, I struggle to buy anything off Amazon these days without inadvertently signing up for a Prime trial.
Mark - buying the hardware I’m afraid (from the site Rob mentioned). Apart from already having too many interests, my son is a precision engineer (metals & plastics) and his critique of anything metal I make is brutal.
Thanks again all.

 

[profchris]

Your issue is cross-grain expansion of the top with humidity changes, which will tend to pull open the joints at the ends of the lid on the cross-grain side. Or crack the top if it shrinks more than the end piece. Oak expands a bit more than, say, mahogany.

If the top is not to take any load, you might consider making it quite thin (3 or 4mm) with some bracing underneath and giving it a small curve lengthways - maybe a 6-8 mm rise in the middle compared to the sides. I'd do this by shaping each end piece to the curve and then making braces every 100mm or so with a matching curve (pretty much the full depth of the lid if you can) from some stiff but springy wood like spruce which will help hold the curve but give a little as the top expands. I'd glue these to the sides of the lid to make a frame. Then I'd simply glue down the top to the braces and ends, probably first clamping along each side and applying heat with a heat gun to persuade the wood to take up the curve before glueing. Make the top a little over-size and plane back to the frame to get a good-looking joint.

The effect of this is to allow the expansion to increase the curve of the top slightly, so it rises a couple of mm, and thus reduce the force it exerts on the end joints. The braces will spring up with the top and so remain attached. The concept comes from guitar making.

If you adopt this, glue up in lowish humidity so the top doesn't risk shrinking all the curve away if you get very low humidity, or it will crack.

 

[Glynne]

Despite several enforced mini projects along the way I have now completed the trunk.
As the trunk is for one of my Grandsons and will probably double as a toy chest for some years, the top had to be solid! So I went for ~10mm oak screwed to battens underneath but with expansion slots to allow for cross grain movement.
Not quite a full WIP but I thought you might like to see some pictures.

All panels - sides, front, back and top all joined with biscuits and edge glued.

To ensure I got a reasonable separation without too much waste, I initially cut a thin groove (1.5mm) using a slotting cutter on a router table with the trunk on it's lid. I then used this as a guide for the hand saw.

Thanks again for the advice.