MDF ? Bad Word?

[TKKids]

So who would shoot me for doing a built in from MDF. Trimming in out with solid wood and using wood shelves?

Looking at it from a cost. The cabinet ply I was using (3/4" birch) has gone up to about $45 a sheet and the MDF is still at $23. Big savings.

Any ideas on where to find some good cabinet ply in town? Still new and looking.

Tim

 

[DaveO]

There is absolutely nothing wrong with using MDF for a piece that will be painted. It will give you the best painted surface. The dust sucks and it's heavy, but it will make a nice painted piece. I would definitely use ply or solid wood shelving as MDF can and will sag over long spans. Solid wood facing will help with the MDF edge sealing and help with a good final finish.
Depending on how much ply you are looking to get you might check with the Wurth Group (AKA Raleigh Hardwood Center) on Poole Rd. just outside of the belt-line or Horizon Forest Products, not to far away for their. Also there is Jackson International at the intersection of Hwys. 42/55/401 in Fuquay. He might not be as user friendly as the others but I've heard his pricing and selection is great. You can find more info on all these places in our Wood Suppliers List http://www.ncwoodworker.net/forums/view.php?pg=woodlist


Dave

 

[McRabbet]

MDF is fine for shop cabinets or painted cabinets, but I would not use it for a formal space set of built-ins where the interior will show when doors are open or if there is not any door (e.g., an entertainment center or book cases). I would also avoid using it anywhere that it may get wet or if there is dampness nearby. A third major drawback is that MDF does not hold standard wood screws at all well -- special screws called Confirmat screws (or similar broad thread screws like Spax screws) are required. It is also very heavy in full 3/4" 4x8 foot sheets (ca. 95 lbs.).

You are correct to avoid using MDF for any shelving because it has very poor structural characteristics (see the Sagulator). Even with edge banding, I would not use it for shelves unless the banding was solid wood at least 2 x the height of the shelf thickness and the shelves were less than 30" wide (I wouldn't use it even then for aesthetic reasons because I'm a real wood user). I built my router table out of MDF and it has stood up well for more than 10 years. I also use MDF for jigs and work surface substrate because it is dead flat and does not expand or contract at varying temperatures.

You'll find that quality hardwood plywood will cost a fair amount more, but it is worth it for quality cabinet construction. Check out the sources found under "Where Are > Wood Suppliers" on the top menu bar.

 

[TKKids]

Thanks. Will research some more.

 

[JimD]

I just got some chinese birch for $37/sheet but it is not from a chain store and is in Lexington, SC. It has filled flaws in the face ply but that works fine for painting (what I will be doing). The place is called the Depot (not home depot) in Lexington.

I use mdf for jigs and also for the raised panel in doors that will be painted. MDF is at the low end of the strength list, below particle board. It paints well but the cut edges soak up a lot of primer. My rule of thumb is to avoid structural applications.

I just made some little trays for keyboards in my wifes classroom tonight with 1/2 MDF scraps. They will be painted. I used my 16 gauge nailer on them but I had to stay about 2 inches from the edge to avoid splitting. I added scraps of 3/4 plywood on the outside to provide a little more strength and stiffness.

Jim