spot of inspiration needed please

[smokeyone]

I have a 6 feet by 2 feet shelf made of the dreaded mdf (15mm) thick.
In need of inspiration to stop the sag in the middle under the weight on it.
Thought of putting 2"by1" edgeways on around it or even buying some steel angle to bolt along the long edges.
Any better ideas please...
Thanks very much...

 

[yetloh]

Think you will struggle with this whatever you do. No possibility of a centre support or bracket I suppose? Is it up against a wall at the back? If so, a batten along the back is the answer. Doesn't need to be very wide so can be unobtrusive.

Jim

 

[MikeG.]

A triangle or two cut from ply or MDF and fastened to the underside of the shelf will throw the twist loads onto the wall, and a batten on the wall will help prevent the back edge from sagging. The triangle/s should be most of the width of the shelf at the top, and the longer the dimension that goes against the wall the better.

Mike

 

[Lord Nibbo]

Have you got room to convert the shelf into a torsion box construction?

 

[smokeyone]

Thanks all for the ideas. It's not against a wall so am stuck when it comes to adding a battern at the back. Wonder if the torsion box suggestion would work. 3" by 1" strips underneath covered in ply - would that help..

 

[devonwoody]

Use the 3x1 to make a new shelf

 

[MikeG.]

The torsion box thing would obviously be a big improvement, but only works because of the tension in the bottom skin. You therefore have to have a bottom skin the same size as the top skin, and that is going to turn this into quite a construction.

Another answer would be to suspend the shelf from the ceiling/ roof. A couple of ties just in from the fron edge, and a couple more supporting the back edge, should do the trick. A wire would be better than a rope, simply because of the stretch in most ropes. Fencing wire with a fencing turnbuckle would do the trick really well.

Mike

 

[smokeyone]

Thanks for the suggestions. Will try the torsion box first.
Cheers

 

[Mailman14]

:?: What's a torsion box?

 

[tja]

:?: What's a torsion box?

In this case a horizontal frame with a sheet on top and on the bottom, the one on top pushing and the one on the bottom pulling to fight the sag introduced by gravity. It gives approximately the same strength (or should that be stiffnes) as a solid of the same thickness but without the weight. Think airplane wing.

Take

 

[Chris Knight]

Pick up a bit of strip steel from B&Q (10-12mm wide, 6mm thick. Rout a corresponding slot down the shelf on the underside. Epoxy the steel in place.

 

[Mailman14]

Cheers tja!