Lipping MDF Shelves

[Chunky Monkey]

Hi all,

I'm making a cabinet to fit into an alcove out of 18mm MDF as it will be painted. The top half of the cabinet will involve the usual shelves, but as the span is approx, 1080mm I need to lip them to prevent sagging. The "client", a friend, wants to keep the front profile as narrow as possible, so I need some advice on the minimum depth of lipping that would prevent sagging. Am I right in thinking that a hardwood lip could be shallower than a softwood lip? And if the shelves were made of 18mm plywood, I could use a shallower lip than a corresponding MDF shelf?

Recommendations gratefully received

Thanks

Jon

 

[mailee]

I would lip it with 1" hardwood but a better solution would be a torsion box shelf, far stiffer and lighter for longer shelves.

 

[custard]

The Sagulator is your friend,

http://www.woodbin.com/calcs/sagulator.htm

MDF sags like wet lettuce. If you need a narrow profile think about wide hardwood lippings front and back.

 

[RobinBHM]

I think mdf is not an option for a 1080mm shelf unless you have quite a big lipping. If its a narrow shelf fixings at the rear may help. Otherwise Id be considering 18mm birch.

 

[bamboo]

I think plywood would be a better option for making the shelves, what's going on them?