I have the Mastercool hydraulic tube double flaring tool and it has not failed to flare correctly even once!
I have done 3/16" tube a dozen times so far.
Without looking, I'd say the tube needs to stick up around 3/16", -it's the thickness of the "upset" tool which is included with a double flare set. If you have a single flare set, you don't have the upset tool.
I have an Imperial kit that is not good at flairing double flares. The upset tool for that kit has a good sized radus where the centering pin comes out of the upset tool. The hydraulic flare tool I have uses an upset tool that has no large radus, thi seems to help it flare better.
I hear the Snap-On flare tool is great.
Here is what Inline Tube says:
"Tips For a Perfect Flare - When flaring tube it is important to read all the instructions carefully. Before you flair the tube, deburr and chamfer both edges of the tube, this allows the tube to roll over and create a smooth edge. To deburr the inside edge use a drill or file and rotate the file in the opening of the tube, the outside edge can be done with a standard file. Tube cracking is caused when the tube is not properly deburred. Do not cut tube with a tube cutter. The cutter when dull, hardens the end of the tube, causing flaring to be very difficult. Flaring tube takes practice and an understanding of how the tools works. Once the practice is put in the understanding will come."
Here is the Team Chevelle page on flaring brake lines.
http://www.chevelles.com/tools/tl4.html
I haven't tried flaring SS, I have heard the tube is pretty stiff, inline Tube says theirs is soft enough to double flare and recomends it be double flared.
http://www.inlinetube.com/cartalk.htm
I think if you are going to use Stainless tube it would be better to use 37 degree single flare on it and aircraft 37 deg fittings all around.
45 deg fittings were made for soft steel brakeline, the 45 deg flare stretches the tube more and will MAY cause cracking of the tube if single flared.
David
[ 06-24-2003, 11:10 PM: Message edited by: davidpozzi ]