Strength of MDF

[Count de Monet]

Thinking of using MDF for my computer build work bench.

Would 2400 x 25mm MDF flex if only supported at the back and ends? I need a long bench with no legs at the front. I will be cutting it to 700 width.

[Skipweasel]

Well, obviously to an extent that would depend on what you put on it - but it will sag quite a bit over time.

If you're cutting it to 700, cut some strips off the offcuts and make a box-girder to run along the front. It only need be a few inches deep to add considerable rigidity. Failing that, a trip to your local steelyard will get you a 7m bit of angleiron for a few quid. Take your own hacksaw, though.

[Andy Dingley]

Yes. Mostly though MDF might not flex immediately or break, but it will cetainly sag over time. You do need to support beneath this. You don't need to support right at the front edge though - you can set it

6" - 9" back, especially if you also support at the ends and bring that bearer right to the front edge.

[The Medway Handyman]

You need - the sagulator!

[Steve Firth]

Short answer, yes. However if you made a box structure then it would be much more rigid.

[Dave Liquorice]

That'll be damn heavy bit of MDF... Like the skipweasel says just put something along the front, doesn't have to be a box section just a bit of 100x20 or similar, broad face vertical, fixed to the legs at each end. With 2400 length I'd also stick a couple running front to back to stop it wibbling or fix it to the top somehow along it's length.

[Malcolm]

or a length of anle iron

Malcolm

[Count de Monet]

I will be supporting the MDF on three sides with battens attached to the walls.

Would the idea below be OK for stopping sag at the front?

[Nightjar]

Putting the angle iron with the vertical bit up would both keep the underside of the front edge of the board clear and protect the front edge.

Personally, having had to move 25mm thick MDF before, I would fabricate a frame entirely from steel or aluminium, bolt that to the walls and use a thinner top.

Colin Bignell

[Tabby]

with MDF is it doesnt tolerate drips on mugs at all well. And its somewhat weak too. I just stay away from the stuff, it has little going for it.

NT

[Man at B&Q]

If it has to be MDF (for the surface finish?), use something a lot thinner and make up a box structure with lots of internal ribs. Think of how a hollow internal door is made.

MBQ

[Man at B&Q]

Because that may well sag over time, depending what it's supporting.

MBQ

[root]

When I made my bench I used a 2400x600 sheet of contiboard with mock lightish veneer on both sides. I used 49x74mm (or 2 by 3) timber for the legs (with cross-pieces), a kicker rail at the bottom and two struts along the front and back to support the length.

Total BoM was 1 sheet of contiboard, 5 2400mm lengths of timber (3 for the lengthwise supports & kicker, 1 at each end for the legs) By cutting the lengthwise supports short, I got the right sized lengths for the cross-pieces on the top + bottom of the legs, so the height is just right for sitting at the bench.

6 years later it's still going strong - despite 2 CRTs, a printer and couple of 'puters on it. No bowing or sagging - wish I could say the same for me!

[John Williamson]

Has anyone suggested some decent 12mm ply with a piece of 100 x 25 softwood fastened under the front?

[mick]

I used blockboard (& intended to edge it with 18mm wide pine where it mattered but never got the round tuit). It's a heck of a lot lighter than MDF and plenty strong enough for a computer desk if you just think about where the support is needed. This desk is about 800mm wide and I can stand on it in the middle. No support along either the front or the back, but there are 2 shelves with a solid back between them.

[TMC]

I suggest 12mm ply with batten at the back and at the ends

Use a length of 75 x 50 at the front rebate the inside top edge to 25mm side by 12mm deep rout or sand the outside top edge top a roll top profile

Set the ends of this into the end battens

Made one like this several years ago no discernable sag to date.

Has been used as a sewing machine/domestic overlocker bench as well as a computer rebuild bench

regards

[BartC]

I think it did help it reducing sag, but my bench was for electronics, nothing heavy. And it could still get in the way, if that's the idea of no legs.

[Andrew]

Support each end on a couple of filing cabinets or hollow block piers. You can stand on it and it won't sag.