Before making a flare, make sure the fitting is on the tube first, or you will need to cut the flare off and put the fitting on and remake the flare.
Undo both sides of the flaring clamp.
Then insert the tube in the flaring tool with the end sticking out about 1/8" and tighten the clamp bolts
Then put the flaring press on and slowly tighten.
Then remove the flaring press, and remove the tube
You will have a beautifully made custom piece to fit your exact need.
Note again, however, that this single flare process is not to be used for brake lines. I show it on small lines mostly because I had the scrap left over and it was easy to demonstrate here, but most fuel lines are much larger. The double flare will be shown next.
Making Double Flares
The double flaring process is similar to the single except that a different tool is used and it it a two step process.
Again, as with the single flares, before making a double flare, make sure the fitting is on the tube first, or you will need to cut the flare off and put the fitting on and remake the flare.
Insert the tube into the flaring clamp so that it sticks out the same distance (red arrow) as the width of the collar on flaring die (blue arrow), then tighten down the clamp.
Now turn the die around and insert the pin into the tube.
Put the flaring press on and tighten till the black die is firm against the the tube clamp (red arrow in right photo).
Remove the flaring press and the black die and your tube will look like this.
Now put the flaring press directly on the previously made partial flare and slowly tighten the press till the flare is right against the edge of the clamp, as seen in the right photo. Then remove the press.
The left photo shows the new double flare still in the clamp. The right photo shows the finished product. You now have a great looking and functional double flare, suitable for brake lines, power steering lines, transmission cooler lines, fuel lines, etc.