1950s Why is this leaking (fuel line)

[dn010]

My point about the marks from the flare tool on the pipe was only to say it appears the tool was one of those cheaper ones you can get from pretty much anywhere. The pneumatic tool's clamp are longer, leaving more indents. Problem with the cheaper flare tool is that it's sometimes difficult to get a perfect flare out of it, sometimes the die doesn't fit perfectly center in the pipe you're working with and the flare comes out lopsided. Then when you do get a good first flare and think you've got it beat, sometimes the die shifts to one side when you're clamping down on it to get the double flare! I've had to redo flares many times with that tool but who really wants to spend hundreds on a pneumatic when you've only got a few to do here or there?

["Cadillac Kid" Greg Surfas 15364]

Just like a lot of things, flaring copper tubing takes a lot of practice and mistakes before you get it right MOST of the time. It is also a skill that can degrade through lack of use. When I encounter a leaking connection (that I did) and I know it's tight enough I don't wast time but just reflate it
Greg Surfas

[tcom2027]

I agree a collet, pneumatic or hydraulic works well in a shop environment. In the field, not so much, especially if the end is close to a bend. Each have their place. I have fifty plus year old Blue Point double flaring tool that does a fine job. The ones available today, Eastwood and the KD double flaring tools work well.

The tool needs teeth to hold the tubing. It has to be tight to keep the tube from moving down in the clamping tool. I's really not a big problem with copper tubing but with hard line brake and fuel lines the clamp has to be very tight. That is one of the problems with some of the modern inexpensive flaring tools, many of which aren't hardened sufficiently or the tooth profile is poor not allowing the tool to get a good bite on the tube.

THe keys to getting a good flare are the outside chamfer on the tube,a perfectly square cut, deburring the ID and OD then and getting the protrusion of the tube correct. Chamfering the OD is a little trickie  to do off hand on a bench grinder and takes practice to do well. It's the key to a good double flare. Same for getting the correct protrusion and using a little lube. I have a milling cutter that puts a nice chamfer on the tube and makes me look like I know how to make a decent double flare that won't leak

tony

["Cadillac Kid" Greg Surfas 15364]

I still use the flaring tools I got when I was 12 years old, 71 years ago and my flares are as good as the patience I put into them

[tcom2027]

About the same for me. I have my dads' Blue Point from around '58 when I was 14 and have had it ever since. It went missing around '68 so I bought another Blue Point from the Snap-On man. THe original showed up packing for my move to California in '79 so now I have two.

tc

[TJ Hopland]

With the basic parallel bar sets setting the tube height and needing the bars to be tight were key elements that took me a while to figure out.  The height is set by laying the proper die on the bars and aligning the end of the tube with the first step on the die.  That is why that step is there. 

The trick to clamping tight is to first crank down on the nut nearest to the tube then crank down on the far side. You do it this direction because the far one has the leverage.  If you don't get it good and tight the tube can slip and you won't get a good flare.  Knowing those tips even the cheap tools can do a decent flare on the small steel tubes. That was all I had and used for many years.         

[David King (kz78hy)]

My best flares are always on the tube with the nut sitting on the table next to me....

[tcom2027]

How true.

Years ago when I had some time to screw around, I took a 3/8 tube, flared both ends and cut it into two unequal lengths. I drove a shaft into each piece, leaving one side long. I bored and threaded one end and cut a corresponding thread  on the  pice with a protruding  shaft. IIRC, a #3-48 thread. I  cut a relief in the long threaded end so when the pieces were screwed together the joint was virtually invisible. To make sure, my final op was to make a couple thousands skim cut along the length of completed tube.

When I had a victim, I'd say "Damn! I forgot, I have to fix a fuel line I left the nut off of. Hold my beer." I'd grab the tube and nut hold both behind my back or turn around and unthread the tube and put the nut on, sometimes backwards and hand it to him and wait for a reaction.   

tony