Keeping flat plank doors flat

[NDRiley]

I'm currently designing a wardrobe with a pair of matching chests of drawers. For aesthetic reasons the client wants to have flat plank wardrobe doors of solid oak to tie in with the design of other elements of the pieces (eg all of the drawer fronts will be a single flat panel of oak). It's a triple wardrobe (3 doors wide). The largest door is 1900 x 460 (the other two are same width but slightly shorter).

My concern is keeping the doors flat across their width and top to bottom. My current strategy is:

1: Use kiln dried quarter sawn oak.
2: Make each door from 5 fairly narrow boards (92mm each).
3: Where there is any deviation from the perpendicular in the orientation of the growth rings to the face of the boards, alternate the boards in the usual "smiles" and "frowns" way.
4: Add a number of cleats to the back of the doors. I'm planning to use hidden blind sliding dovetails for the cleats which looks slightly more sophistcated than the usual screws and allows me to lose some of the depth of the cleat in the thickness of the door (the one on the right in the test piece photo below).

I'm pretty confident that the combination of the above will prevent the doors warping across their width but there is no physical restraint on bowing top to bottom (or, I guess, twisting end to end). I'm loathe to add more bracing to the back of the doors (eg diagonal bracing between the cleats) as I'm concerned it would make what is supposed to be a clean design slightly agricultural (albeit only on the inside).

Any thoughts greatly appreciated.

Many thanks

 

[AJB Temple]

I've made quite a few planked and ledged (not braced) oak doors and I think your design will be fine as long as the oak is well seasoned and dry. Don't be tempted to make the planks too thin and plane evenly on both sides.

 

[Ollie78]

Looks like a sound plan, I can`t think of any other strategies really, a lot will depend on the timber. I foresee alot of careful squinting at boards in your future.
You could of course make two of everything in case one gets bendy !

Ollie

 

[bjm]

If you want peace-of mind you can buy an insert that sits in a groove the length of the door (acts similar to a guitar trussrod) and can be tightened/loosened as needed to straighten a door. Can't remember where I've seen them either - Hafele and others do them. Not used them personally so can't say if they work.

Edit - search for door straighteners.

My main concern would be how do conditions in your workshop compare to conditions in the clients house? Any effect could take weeks/months to manifest. Personally I'd be looking to do this with veneer on a stable substrate but I know that's not always do-able.

 

[Setch]

Are you not concerned about your gapping changing radically with humidity? Changes in width that would be easily accepted on a planked doorway will look pretty awful on a nice bit of furniture

 

[Cabinetman]

As others have said, pick your timber really carefully, really straight grain, it’s always a gamble, not sure you need the cleats though, I wouldn’t be so worried about the door being bowed it’s a corner to corner twist that is a nightmare to try and fix. Ian

 

[TheUnicorn]

As others have said, pick your timber really carefully, really straight grain, it’s always a gamble, not sure you need the cleats though, I wouldn’t be so worried about the door being bowed it’s a corner to corner twist that is a nightmare to try and fix. Ian

which begs the question how do you sort, or prevent a twist?

 

[Cabinetman]

Brian, I came across a system like that on some really expensive wardrobes, the back of the mirrored doors had two rods that went up and down inside the 18? millimetre MDF of the door and there was a rubber cover (x four) which you could remove to loosen or tighten to counteract the bowing caused by the mirror. My job was to remove the mirror intact, 8‘ x 2‘ and have it cut at an angle across the top as with the door. – My crazy brother-in-law, but it did actually work! Nobody was more surprised than I was when we got the mirror off in one piece.

 

[bjm]

I've only read about them - never seen them or used them!!

 

[Cabinetman]

Well Mr unicorn, I guess it’s just good old woodworking methods and a pile of luck, as I said check the timber is really straight grained. Make sure you’re morticeses are sunk straight and use well seasoned kiln dried timber.

 

[Cabinetman]

Brian, I think you’re a very lucky man, I was very glad to be finished with that job. Another part of the job was a pocket door which again involved a mirror, on the front of a sheet of plywood, even though it was marine ply – yes the expensive stuff, it had been stored badly and was twisted, I don’t have a picture unfortunately but I had to hide a stainless steel wire in the door to pull the twist out of it. It was one of those crazy jobs, and it actually did work!!

 

[bjm]

Only job I'd done where I thought they might be needed was on some sliding doors the client wanted but, in the end, the doors were fine!!

 

[deema]

A solution not yet suggested which I’ve used on oak doors is to cut the planks in half, plane them and then turn one side around and laminate it back on to the other half. Keep the cut planks the same way around length ways, ie don’t top to toe. Any stresses in the timber will act against each other.

 

[Cabinetman]

That’s an interesting way of doing it Deema, it would take a lot of cramps! I’ve just seen that morticing machine on your "name badge ". That would fit in perfectly with that other thread that I started on old equipment.

 

[johnnyb]

its always a pain on this type of door. we try and avoid making them esp double doors which can turn out really wonky.but they are always asked for as they look rustic.

 

[deema]

It does need a few clamps, but using a long open time glue you can stack and clamp the laminated pieces with plastic in between to make it a one time glue up.

The old iron is being operated by my great grandfather! my grandfather and father also used that machine. You needed to wear a cap otherwise the drive belt which had no guard by design was perfectly positioned to grab your hair and make you prematurely bald!, the good old days.

 

[Cabinetman]

Yes that makes sense, Nasty getting a lump of scalp torn off like that – yes the good old days ha ha

 

[NDRiley]

Thanks everyone for your help - much apprecaited. Plenty of food for thought there.

Not heard of the door straighteners before Brian so thanks for the intro.

I'm inclined to just go for it (taking heed of the sound advice above) and see how it goes.

 

[Hornbeam]

Hi Norris. Your client wants solid oak doors, you say for aesthetics but more likely because he thinks this is better quality. The best way to get a flat door would be lipped and veneered on a stable substrate. You could use slightly thicker bandsawn or purchased 2.5mm oak construction veneer. This would also be thick enough to detail panel joints if required. If you go too thick though you could end up with movement issues of the veneer relative to the substrate
Ian