I've made a few tee hinges, in everything from silver to forged steel, but I'm not exactly sure what you mean by the term "knuckle". If you mean the hinge barrel, I make them by a couple different methods, depending on the material and the scale of the hinge.

For small silver hinges, I usually roll/draw tubing for the barrel and cut it to size and solder in place. This produces very consistent and concentric hinge barrels.

For many of my forged steel or bronze hinges, I simply roll the barrel over the edge of the anvil, using a hammer, and true up over a drift pin. When the hinge barrel must be incorporated as part of a doubled-back, forge-welded overleaf, it gets trickier, but can still be done the same basic way.

On forged hinges where I have to make a fair number of them the same size, I will make a tool to roll the hinge barrels. This tool is similar to the one that Donald Streeter shows in his book "Professional Smithing." Using the tool, it is not possible to create a hinge barrel that is welded, or doubled-back, but it does produce a good, round barrel with a tightly closed seam if done correctly. On simple pintle hinges, this is a quick process and makes them profitable, as well as attractive. On tee hinges, or leaf hinges, where the barrel is segmented, I do both leaves with a full barrel and mark and cut away alternating segments on each leaf. A little fitting with a file and they mate up perfectly.

Segmented barrels can also be done over the edge of the anvil and then cut/filed to create the segments.  That was the method I used for these silicon bronze hinges for a chest project:Hasp for Chest: This is the hasp for a "treasure chest" engine cover in a sailing ship.  There are also a pair of hinges that match.  All the hinge barrels were rolled over the edge of the anvil using a hammer, then cut/filed to create the segments and get a snug fit.  Material is 1/8" silicon bronze, hot forged.