Carpentry and Woodworking - Making your own thresholds

I'm restoring an old house, and one of the things I need to do is rebuild some of the thresholds. My initiual attempts at doing this have not gone very well. The thresholds have to be notched to fit around the profile of the door frame and of course nothing is square.

The original craftsmen 130 yrears ago managed to get the thresholds nice an snug all around using nothing but hand tools. I end up with gaps all over the place.

Are there some tricks to doing this?

Several companies make an adjustable jig for transferring profiles. Normally, they're used for molding, but would be very beneficial for your application.

Simplistically, it's a bunch of THIN rods (either plastic or metal) that are held in place by a frame. The rods are adjustable, allowing you to take a profile of what you're trying to match and transfer it to the work piece.

Here's an example:

http://www.rockler.com/product.cfm?page=10668

Depending on the profile of your threshold and your door jamb, another approach might be to undercut the door jamb, and slide the threshold under it. This wouldn't work if your threshold is raised in the center, beveled on the sides, but would work for a flat threshold.

This is the approach I use when using a marble threshold, or tiling under a door jamb. A turn-of-the-century house I used to own had flat thresholds, the width of the door jamb. They cut the jamb to fit on top of the threshold, but extended the moulding on both sides of the door all the way to the floor. I cut the ones I did by holding a hand saw flat to a scrap piece of stock that was slightly thinner than my threshold.

I've thought about undercutting the door jamb, but that seemed like cheating somehow. I guess those old-timers relied on skill, experience and patience, none of which I seem to have.

I recently replaced a threshold below a set of double-doors between our den and deck. And, I undercut the vertical wood pieces (stops, jambs, whatever they were) to slide the new threshold underneath on both ends. That way when the water runs down it can't run into any gap. After installation, I still caulked along this joint.

The saw I used to do the undercutting is a flat, fine toothed saw I bought at Harbor Freight for cutting off dowels flush. It's thin blade and sharp teeth are perfect for undercutting. I just layed a small piece of scrap board next to the wood I was cutting to guide the saw blade.
--> Here's a link to the saw I'm talking about: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39273

One other thought: I angled my new threshold slightly for the water to run off. The previous one was flat and eventually rotted out.