Bill,
Some tips on using MDF:
MDF really sucks up glue, so you’ll have to apply it to your glue areas in two coats, otherwise you’ll have glue-starved joints. First start by applying a bead of glue to your gluing surface and spread it out with your finger. Assemble the two pieces and then pull them apart. You’ll probably see that most of the glue was soaked up. So now add that second coat and again, spread it out with your finger, and then assemble the joint for good.
If you’re ever using screws, make sure to countersink the part where the screw comes OUT of the first board and into the other, as well as the normal countersink; that way, if you get a little bit of mushrooming, it will go into the countersink and won’t interfer with the two boards coming together.
Also remember to drill shank-sized holes in both boards you are screwing together and, if possible, use screws specifically designed for MDF. They have deeper threads for a better bite into the material and are straight-shanked, as opposed to tapered. A standard tapered screw can split MDF.
For painting MDF, let me quote from Vol. 15 Issue 86 of ShopNotes, page 23 – an excerpt from an article on using MDF to make a thickness sander…
“Just like glue, the edges of MDF readily absorb paint. What you can end up with is a noticeable contrast between the smooth faces and rough edges… To solve this problem, I take a couple of simple steps. First, I seal all the exposted edges with drywall joint compound… It looks like a mess, but it actually goes on easily with a putty knife or even your finger. And when dry, the excess sands off with a minimum of effort. Then, before applying the topcoat, I seal everything with a coat of primer. The top coat will then build quickly to a smooth durable, film.”
Also remember to use the best lung protection you have available when cutting it with power tools. MDF has lots of nasty stuff in it that you definitely don’t want to inhale.
Oh, yeah, and what Dennis said… if possible, consider using a solid piece of MDF and routing out the “panel” with profile bits on your router. Once you get a template or two made up, it shouldn’t be much trouble.
Hope that helps. Good luck, brother.
-- Ethan, http://www.merganserwoodworks.com, http://greystonegreen.blogspot.com/