Making t-molding

[dwg]

I need to make some t-molding like this that will be about 4 inches wide.  How would I cut the curve at the top?
                            Thanks for any help.

[Gary G™]

Rethinking this:
If you have a large router and bit, it's the way to go.
Using the TS, you can rip lines in the board close to the finished curve, then plane and scrape, and even sand.
Again, the T is last.
If you're uncomfortable making the T after making the top, you can make it as 2 pieces.

[Aram]

I need to make some t-molding like this that will be about 4 inches wide.  How would I cut the curve at the top?
                            Thanks for any help.

Depending on the width and curvature, you could do it on a router table, cutting a half-curve from each side, curved side down. You would have to devise a way to keep the piece from rocking, lots of solutions for that, but an issue you would have to address.

[DaveR1]

How much of it do you have to make and in what lengths? What have you got for tools?

[robert146]

Is the "Tee" shape necessary? It's a lot easier without it.

[handi]

A lot depends on how muck you need to make, and what your budget is.

If you need one piece 4 feet long, then a couple of bevel cuts on the TS and hand plane the rest.

If you need 100 lineal feet, I might be looking at buying some custom knives and having it run on a shaper or Woodmaster planer/molder. When I had my Woodmaster, I could easily have made the knives and run that profile at 4" wide.

Short of the Woodmaster, I would NOT try to make that with the T cleat on the bottom. I'd form the dome and groove the bottom to accept an added cleat.

[Steve N]

There is a structural, as well as a more common sense reason that what you can find is 2 to sometimes 3" wide. Commmon sense because 2" has been found to be the right width for a door above a rooms transition to cover it. They aren't considered to be an adornment, but a common sense way to make the unsightly gap between 2 surfaces go away. The actual taper as Ralph pointed out need not be round. Actually a beveled edge makes for a stronger piece.

Now the structural part is increasing them up to a wider width you are creating 2 separate steps, one on either side of a weakness. Wider sides make for more available room for your weight to come down on one side or the other, and you will quickly crack the wide ones unless you happen on the perfectly grained wood that will resist the tendency for the wood to break.

I've not really seen this written anywhere, but old Aden, my trim carpentry teacher taught me this when I was a young lad. Most of his lessons were based on a lot of experience. You can get more info online if you look at "transition molding" Back when I was swinging a hammer it was always transition molding, today everyone wants to shorten everything, so T molding.

[Steve N]

Is the "Tee" shape necessary?  It's a lot easier without it.

You are bridging over 2 different surfaces, sometimes with slightly varied heights, the T goes into the void between them. It anchors it in place, and keeps it from shifting. A true Craftsman would "fit" each transition piece into each threshold so that it almost perfectly mated the void from both sides. Today, time is $$$$$ so forget that.

[Brian in sunny FL]

Maybe a router bit like this?  This is the largest one at 1-3/4" cut length.

https://www.holbren.com/Whiteside_Machine_1480

[Bob10]

I was making some today but didn't go with a curve.  Sanded a round over on one side and the on the side that dropped to the lower surface used a panel door bit to reduce the height where it ended on the lower surface.  Sanding was my finish method as was easy to follow the contour of the panel bit.  It would have been way easier if the transition was a straight run but this floor angle off in another direction