MDF Vs Ply

[Troy]

So i looked through the forum and i couldn't find an answer...

Whats your preference AND why?
What thickness?
Do you use the same throughout the entire cabinet?
Does your cabinet have some sort or "internal frame"?
How do you treat your surface, paint laminate etc etc?

I ask because to me ply would seem the better alternative for strength and resistance to water etc but MDF has a smoother finish.. i made my cocktail cab before i found this site and used ply, and i really should have done some surface finishing before i painted it... you live and learn i spose....


Troy

[ScottS]

Sounds like you want Medium Density Overlay. It's a plywood core with an MDF-like surface finish. Often used by sign manufacturers because it paints so well. I, personally, wouldn't use MDF for a cabinet. It's too heavy and offers too little strength. It's advantages are that it's dirt cheap and you can route complex profiles in it without having to worry about voids, grain, etc. For me, neither of those things is really an issue.

I probably wouldn't use either.

MDF is too heavy and offers too little strength. It's advantages are that it's dirt cheap and you can route complex profiles in it without having to worry about voids, grain, etc. For me, neither of those things is really an issue.

Plywood is light and strong. Unfortunately, it's more expensive and takes longer to prep for finish and paint. Cheap plywood (e.g. CDX) is of such poor quality that it's generally unsuitable for use in a cabinet. If I wanted something that looked like wood, I'd use furniture-grade plywood.

For a painted cabinet, I'd recommend Medium Density Overlay (MDO). It's, essentially, a plywood core with an MDF-like surface. It's often used by sign makers because it is so easy to paint. You get the strength and lightness of plywood, with the paintability of MDF. MDO can be difficult to find, however, and likely isn't any cheaper than decent-quality plywood.

If I didn't want to spend any time on finishing, I'd used black melamine-covered particle board. It's only slightly lighter than MDF and slightly heavier. Gluing to the melamine surface requires special glue (e.g. RooGlue Clear). And if you don't have a high-quality saw blade, you'll get tear-out along every cut line that will make the finished piece look like junk. That said, if you have the necessary tools melamine can get you good results quickly. Probably twice the price of MDF, but less expensive than furniture-grade plywood. Throw some graphics on the side and some colored T-molding and you can put together a very nice cabinet very quickly.

[Kaytrim]

Even though MDF can be hazardous to your health the ability to shape and paint out weighs the differences over plywood.  If you go with plywood you need cabinet grade on both sides.  This is some expensive stuff especially in 3/4" because that is the standard thickness for a cab.  If you go with 1/2" stuff you will need some support system and the t-molding is limited for color choices.

I use 3/4 MDF in all my construction though I may drop down to 1/2" for some small stuff.  As far as any support all you need is some 1x1 material for screws and glue if you want some real strength.  Otherwise pre-drill and use screws and glue.  Be extra careful with routing for t-molding if you use screws too close to the edge you may wake up in the hospital.

[ARTIFACT]

3/4" quality plywood (Birch) is not that expensive... I bought 3 huge sheets (4'x8') for my cabinet for $34 a piece, and have about half a sheet left. That's ~$100 for ALL of the wood I needed for my cab... I built an internal frame as well, out of 2x4 lumber ($2 a piece).

I like working with it... I don't have enough experience with MDF to comment/compare, but I like how STRONG the plywood is.

[shardian]

I saw furniture grade plywood on sale at Home Depot last week for $28 a sheet. I had to do a double take. No clue on the type or anything, but it was pretty nice stuff.

[ScottS]

If you go with plywood you need cabinet grade on both sides.

Why? Nobody will see the inside. If you have a specialty lumber yard that will sell you plywood with one cabinet-grade face and a lower-grade back there's no reason not to go for it! Around here, plywood like that is often referred to as "shop grade". I dunno why. I bought some "shop grade" cherry plywood that I used for storage cabinets and it's really some of the nicest stuff I've used. The backs weren't perfect, having the occasional patch or fill, but they were good enough for inside of a cabinet!

As far as any support all you need is some 1x1 material for screws and glue if you want some real strength.

If you use plywood and know what you're doing design-wise, you don't need any additional supports on the inside of the cabinet. I built snake cages out of melamine-covered particle board without any internal bracing. The bottom cage of each stack is probably supporting 200+ pounds without any problems. And melamine isn't nearly as strong as plywood!

[fixedpigs]

If you go with plywood you need cabinet grade on both sides.

Why? Nobody will see the inside.

ah...don't forget the all too common offset lip that shows...you do see both sides of the wood...just not much of the inside...

[sstorkel]

ah...don't forget the all too common offset lip that shows...you do see both sides of the wood...just not much of the inside...

If you're going to go with this design and if you're going to have a wood-grain cabinet then... it's probably still not an issue unless you're going to have a huge lip. If you're going to paint your cabinet, like most people, then you really don't need high-quality plywood at all. Just something that's straight and relatively smooth. Knots and cracks, if there are any, can be filled with Bondo. By the time you prime and paint, you won't be able to tell what material it's made of... unless you try to move it!

[nostrebor]

Given only the choices in the poll, I would use MDF. It's flat, has no voids, and takes paint better. It can be assembled using good jointery to be just as strong as plywood. Frames are not required if you connect it together correctly. The wiki has tips for this.

As stated above, the best choice is a quality MDO sheet. It is assembled specifically for outdoor applications such as signs, and will take paint just like MDF.