Originally Posted by sedanbob
Assuming you are double flaring mild steel tubing. Preparation is key. I had my best luck cutting the tubing with a dremel tool w/cutoff wheel, followed by a fine file to make sure it was even and square. Used the file to bevel the outside edge, and a countersink bit (by hand) to de-burr the inside edge. Make sure the tubing extends the right amount through the clamp (usually a hair more than the thickness of the side of the 'button'. Clamped it tight as I could, put a drop of oil on the button, then put the button on the tube end to start the first stage of the crimp. I always had to make sure my tool was centered before tightening - there was a little play, and just a little can make the flare crooked. I was also careful not to tighten the second stage to flatten the flare - let the fitting do that last little bit. Practice makes perfect. And always remember to put the nut on first - nothing worse than a perfect flare you can't use. Good luck!
NOTE: I would use brake fluid rather than oil or cleans the finished piece before installing as oil is not compatible with the seals in the calipers/wheel cylinders
2) most buttons or tools/ have a line on then to show how much line needs to be outside of the clamp