MDF Question

Sure, depending on the design. MDF has a lot of flex, but built properly, the edge strength can support a lot of weight. I'd run a couple of support strips under the 27" span on the top.

close to the edges leaving about 3" from the edge all the way around..

I was thinking about running a top strip (1 1/2" wide ) on the inside by glueing and nailing to give more straighth. and also down all the corners to give more to nail or screw into.

Again I was debating between 1/2 and 3/4" What is your thought?

Don D.

Edw> >I have been asked to built some slot machine bases for portables units.

The furring strip idea is good, especially since the weight is squarely on the top, not on the edges where the most strength is. I'd go with 3/4", but

If I used 1/2" for the top, I'd had two braces going the 27" direction, probably 3 in the short direction. Plenty of strength that way, like a honeycomb. Since the machines are portable, they are also subject to some abuse in transit.

An 1-1/2" on the flat still flexes quite a bit. 2" on edge would give you more strength, but makes it harder to attach as MDF end-grain is useless in terms of holding screws or nails. 3" wide would be better if let in to an 1/8" dado with lots of adhesive.

FWIW YMMV

Screws and nails don't hold very well in MDF. Use bisquits at 6" centres for strength and durability -- and you can glue the 'endgrain' of mdf onto the hardened surface just fine, b.t.w.

My 2 cent's worth -P.