My house, like the majority of houses built in the US over the last 50 or so years, has cheapo hollow core interior doors. (this particular house was on such a tight budget that even one of the exterior doors is hollow core). My son and I have been working room by room to upgrade the lighting, electrical and insulation, I guess the insulation cannot be considered an upgrade, since the house had none. We have also been ripping off and replacing the drywall in part to add insulation and to get rid of the horrible texturing job. After upgrading one of the bedrooms I wanted to change the on-suite bathroom and walk-in closet doors. The doors are 2'2" x 6'8" and we wanted to use single light door with obscure plastic. After being quoted $500.00 per door with a 2 month delivery date, I decided to make them myself. I recently acquired, for free, about 2,000 board feet of various hardwoods from a collector that had passed away. And out of that I selected three 2" x 14" x 7' planks of Philippine mahogany (also known as Luan). I happen to be making 2 identical doors.
Wood for styles and rails (calculate this based on the size and number of doors).
(style refers to the vertical pieces, rails mean the horizontal pieces)
Dowels for the joints (in my case I used 8 1/2" x 3" per door)
Blue painters tape
2 part epoxy resin glue and microfiber thickener.
Warning this method of making doors uses sloppy fit dowels to compensate for a large degree of misalignment, based on my not having a horizontal drill press to properly align the holes. you must use a glue that gets its strength from a wide glue line, as far as I know epoxy is the only way to accomplish this. using any other kind of glue will result in failure.
Chop saw or radial arm saw
Sander (I prefer a DA but a belt sander in experienced hands will do)
Drill press (big enough to fit you longest rail on end). I think you might be able to get away with using a hand drill with this sloppy fit system.
4 clamps (wide enough to clamp the width of the door)
mallet (to help align the door, when gluing up)
hammer and 1" chisel (to mortise the hinges)
Lock boring jig, also called a lock installation kit (Harbor Freight about $10.00)
Boat builders slick (optional, I use it because its one of my favorite tools)
Step 1: Cutting and Planing the Styles and Rails
I don't have a jointer so I straighten the boards on my table saw by nailing a straight edge to the fence side of the board and ripping the opposite side. once the boards are straight, I ripped them to 12" (save the offcuts and use them later for the stops) wide so they would fit in my planer. Once planed ( I made mine 1.5" thick) I then ripped the stiles to 6" and cut the rails bottom rail 12 inches and top rail 6" . the math is simple a 2' wide x 6'8" tall door opening for example would be 6" wide styles with 12 " wide rails. This will leave enough material to cut the door bevel and get you 1/16" to 1/8" clearance once the door is set in the jam.