flat panel doors

[bill walton]

I am looking at a project that consists of a bunch of flat panel doors, 23x84x 3/4 for cabinets lining the sides of a long closet/dressing room. They are to have a specific matched veneer on the faces and maple veneered backs. Because of the quantity and size I will most likely have panels custom pressed. The customer doesn't want battens on the inside, how concerned should I be about warping? if the answer is highly, what batten configuration should I insist on on the inside. Thanks

[Mel Fulks]

You mean the doors are flat,as in appearing to be one piece? Or a five piece door with a flat panel?

[Jamie Buxton]

I think you're talking slab doors -- just one big panel. You should be okay with MDF as the core. MDF with veneer faces is not likely to warp in service. The trouble with MDF is that it doesn't hold screws well. With slab doors, you're probably going to use cup hinges. Be sure to use the kinds intended for MDF, or glue in hardood plugs for the screws to bite into.

[bill walton]

yes slab doors, and the cores will not likely be mdf, most likely baltic birch

[Jamie Buxton]

Another way to approach these doors is the same way as most interior passage doors are built: hollow core torsion boxes. And they'd be thicker than 3/4" -- more like 1 1/4". That style of construction developed because it is a way to reliably make doors that are flat when they're built, and stay flat in use.

[Mel Fulks]

That sounds pretty heavy. I think a light weight premium mdf would work better . If you're going to sub them I would ask them how straight and stable THEY WILL GUARANTEE THEM doing them their way.

[Jeff Duncan]

If you want flat your going to use mdf, and lightweight is preferable....to me anyway! You also have to make sure the veneers are the same thickness on both sides and that both sides get equal finish.

Alternatively you can use other core materials.....in which case charge a LOT b/c you'll be going back:(

good luck,
JeffD

[Paul Murphy]

I don’t know much about it, but it should be lighter than MDF:

Resin Impregnated Honeycomb http://www.vacupress.com/accessories.htm (http://www.vacupress.com/accessories.htm)

[Jamie Buxton]

I don’t know much about it, but it should be lighter than MDF:

Resin Impregnated Honeycomb http://www.vacupress.com/accessories.htm (http://www.vacupress.com/accessories.htm)


I tried that honeycomb a while ago. Shipping was oddly expensive. Between the shipping and the cost of the material, the stuff cost a lot more than I wanted to spend. I went back to making my own cores from 1/8" plywood grids. It is much less expensive, and you get to make it any dimensions you want.

[Paul Murphy]

I tried that honeycomb a while ago. Shipping was oddly expensive. Between the shipping and the cost of the material, the stuff cost a lot more than I wanted to spend. I went back to making my own cores from 1/8" plywood grids. It is much less expensive, and you get to make it any dimensions you want.
Good things to know, thanks Jamie. I for one would be interested in seeing more about how you build your torsion box doors.

[Jamie Buxton]

Good things to know, thanks Jamie. I for one would be interested in seeing more about how you build your torsion box doors.

Here's a link to notes from a talk I gave to my woodworkers club years ago. http://www.bayareawoodworkers.org/BAWA6TeckTalkTorsion%20Box%20Construction.html

[Paul Murphy]

Thanks Jamie, I saved a copy for future use. I'm a big fan of engineered solutions. Any guidance for us on the grid spacings you like to use?

[johnny means]

Typically, your ultra high end Italian lacquer type cabinets would be done using MDF or particle board. I know some people just cringe at the thought, but when flatness is of the utmost, nothing is better. Screw holding doesn't mean anything if your using cup hinges, a good pair of Insertas would hold fast in a piece of cheese. Doors of this size probably should be on the thicker side. I would move up to 1" and go with particle board to cut down on weight. I wouldn't use Ultralight because it doesn't offer up much in the way of dent resistance and would leave your corners and edges vulnerable. As far as all this talk about honey combs and torsion boxes,

That's a bunch of malarkey243447

[johnny means]

You could also use phenolic backed veneer which would avoid any warping do to humidity issues.

[Mel Fulks]

I agree thicker doors would be easier , but also uglier. To me even the 3/4 inch overlay for this application is a clunky motel room closet look. If the cabinets are to be a dark color the light maple color might look OK.If it is all to be light maple I think it will be a weak design with complaints about uneven shadow lines and fit.If the plan is still for the doors to be subbed I would leave construction plan and warranty to the sub.Dictating construction detail would IMO would be assuming some responsibility for problems. To me the best design would be 1 and 1/4 (or 1 and 3/8 inch) inset doors. Did a similar job a couple years back. Cabinets had doors 88 inches tall with a number of different widths all 1 and 1/4 thick inset. Two flat panel design with applied moulding on face panel perimeter. Boxes went first,then later the perfectly straight pre fitted doors pre routed for brass butt hinges. Some will say " this is what they want ,the design is not our problem". I have found the client will often complain and hold money when their own amateurish design is the only real fault.

[Jamie Buxton]

.. As far as all this talk about honey combs and torsion boxes, That's a bunch of malarkey..

No, it is not malarky. There's hundreds of millions of interior doors in this country that are built this way.

[johnny means]

No, it is not malarky. There's hundreds of millions of interior doors in this country that are built this way.

No doubt. I realize that this type of construction definitely is useful and in many situations the cheapest, lightest, most ridgid way to engineer a panel. But in a small simply equipped shop, it's over engineering. The labor required to build such a door just doesn't make sense when simply cutting up a sheet of particle board will do the job.