I want to replace a few interior doors. The current doors are beat up
luan and I'll replace them with solid six panel doors. I've replaced
one of them and it's not quite right, so I'd like to figure out how to
this correctly before proceeding with the rest.

All of the door jambs are very solid oak so it's seems a waste to
replace with prehung doors. Also, the luan doors all work perfectly,
so they are hung correctly.

I thought it would be a snap to simply make the new door exactly like
the old one. So I laid the old and new doors on top of one another
and they appeared to be exactly the same size, except for height. I
cut the bottom off to size, carefully marked, measured and cut out the
hinge mortises and door knob hole. When I hung the door it was
apparently a millimeter or so too wide. It struck the jamb very
slightly before it would close. I used an electric planer to shave
off some of the door on the knob side. Now it closes but binds on the
hinge side. It seems I may have made the hinge mortises too deep, so
the hinge is sunk a bit below the surface. I'm thinking I need to
shim beneath the hinge to bring it level with the door surface, but
then I'll probably need to shave some more from the other side. This
bothers me because I thought the old and new door were the same width
to begin with, so maybe I'm doing something wrong if I need to keep
planing it down.

Any tips or references to practical guides would be appreciated. The
websites I can find seem to gloss over the tiny details that seem
crucial for obtaining a good result.

Thanks