Sadly, MDF jambs are seen more and more these days. I hate them. Just can't stand them. But sometimes when I trim out a project, they are there... and since one of my hats is a "trim" carpenter... I use what is on site. I don't like them because they aren't rigid enough to keep the jamb from deflection, are more prone to movement due to humidity than wood, and worse, they take double the amount of time to shim them properly when hanging as you need twice the shims.

So, bad news. MDF comes in all types of densities, resin bases, and prep methods. Cutting with hand tools is tough. Cutting and maintaining the depth you need to properly set a hinge is almost impossible with a chisel.

Porter Cable to the rescue! I bought this gadget several years ago and have used it to hang a couple of hundred (I do mean that literally) doors. The double headed nails are long gone, replace by fine threaded sheet metal screws. It works well if you are patient, set your router right, and do a few test cuts to make sure you understand the setup and use of the template. And it even comes with a "perfect fit" router bit matched to the jig and will cut a nearly perfect radius for almost all hinges.

I dismissed this as a plastic piece of crap when I saw it, but my old commercial rep told me to try it, and bring it back if I didn't like it. Now it is a permanent fixture in my door kit with the attending router, hole saw kit and 1" paddle bit for latchsets and deadbolts.

http://www.amazon.com/PORTER-CABLE-5...hinge+template

These are also available at some Home Depot stores, which is where I bought mine.

Robert