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Having trouble flaring fuel vent line

bertschb

bertschb

Well Known Member
Friend
I'm using a flaring tool for the first time on my fuel tank vent line and I don't like the results. After eight attempts with the same results I'm getting pretty frustrated. I'm using a new Ridgid Model 377 flaring tool. The instructions say "Once the clutch releases, turn the handle at least two more full rotations to ensure a uniform, smooth flare surface". I've tried that along with no additional turns and 4-5 additional turns. Same results. The flare surface looks fine to me. If you look at it from the end, it looks great. It's the uneven sides of the flare that aren't right.

The only thing I can think of is the piece of scrap tubing I'm using to practice these flares on was used to practice bending the tube as well. Some parts of it have been bent then straightened then bent again. Could that have caused the walls of the tubing to be uneven in some places leading to the uneven flares?

Before I flare, I cut the tube with a Ridgid tube cutter. When using the cutter I gently advance the knob after every couple of rotations to minimize deforming the wall of the tubing while cutting. I then use a very small round file to gently debur the inside of the tube. After that I use a small flat file to smooth the end of the tube. Finally, I use a purple Scotchbrite pad to debur.

Any ideas as to what I'm doing wrong?

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JonJay said:
That’s weird.
Is the die square to the tool?
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As far as I know. I just went out to the hangar and checked the tool. I don't see anything obvious that would lead to one side of the flare being taller than the other.
 
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I’ve had the best luck with the Roto flare tool made for aircraft. The ones I used from the local hardware stores only really work well on copper. I always had issues making aluminum or steel lines for my cars with those generic flaring tools. After I bought the high end aircraft flare tool I finally saw the light!
 
What does the cone that drives the flare look like? I noticed the roto flare has a conical triangular die that works the aluminum really well not all at once like a cone shaped die. Not sure if that makes the difference but it really makes professional looking flares. Almost like a factory did it.
 
Something is wrong with that tool. Never had any problems with both Roto Flare tools I have owned plumbing the 3 airplanes I have built. Send it back.
 
Majorpayne317641 said:
What does the cone that drives the flare look like?
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The cone doesn't move straight down into the tube. It rotates (and "wobbles") as it drives down into the tube.

This is what the Ridgid website says about it:
"Hardened steel flaring cone, eccentrically mounted in needle bearings, produces rolling action for even metal flow. Gives uniform flare walls without galling."

It also has a clutch that releases automatically when the flare has been fully formed so you can't "over" form it.
 
I have that same Ridgid tool and haven't seen anything like you're showing. It looks like your cut isn't square or somehow the line isn't square in the jaws (which would seem almost hard to do). The one thing I've noticed with it is that on the soft aluminum if I crank it until the clutch releases, I get flares that are way overdone. I have to count my turns vs rely on the clutch. Other than that, I've been pleased with how it forms flares.
 
Unless there is a manufacturing defect in the tool itself, the next guess would be that the end of the tube is not square and smooth. The way that I prepare the tube is to cut it with a hacksaw (rather than the plumbing type cutter, because the latter deforms the end of the tube). I then smooth the end of the tube by inserting it through a hole (1/4" or 3/8") drilled perpendicular in a 2" block of wood and use the surface of the wood as a guide to sand the tip of the tubing square, using 320 grit sandpaper. This works consistently.
 
skelrad said:
I have that same Ridgid tool and haven't seen anything like you're showing. It looks like your cut isn't square or somehow the line isn't square in the jaws (which would seem almost hard to do).
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I use the Ridgid tubing cutter (not a hacksaw or bandsaw) to cut the tubing. It sure looks square to me and again, I've done 8 flares and they all look the same. As you've said, I'm not sure how I could get the tubing in the jaws crooked - eight times no less.
 
PaulvS said:
...I then smooth the end of the tube by inserting it through a hole (1/4" or 3/8") drilled perpendicular in a 2" block of wood and use the surface of the wood as a guide to sand the tip of the tubing square, using 320 grit sandpaper.
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That's a great idea. The end of the tube looks square but I'll try that tomorrow.
 
I spray LP2 lubricant on the tool and on the aluminum tube to help it go smoothly. I use the debuting tool to smooth out the fuel tubing before put it inside the tool. Don’t over flare. Common mistake which I did.

After the tube was flared, clean the edge with fine sand paper. The next step was taught to me my a master builder. Run a 45 deg rivet deburr tool inside the face of the flair. This will smooth out the inside face so it will mate with the AN fitting perfectly. Damn this small detail can make all the difference
 
bertschb said:
I use the Ridgid tubing cutter (not a hacksaw or bandsaw) to cut the tubing. It sure looks square to me and again, I've done 8 flares and they all look the same. As you've said, I'm not sure how I could get the tubing in the jaws crooked - eight times no less.
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usually, what works best for me is to make very small incremental changes to the beading with the tube going around 2-3 revolutions for each minor depth adjustment...

Not sure if that makes sense? basically lots and lots and lots of spinning, as you very slowly increase the dept of the bead. usually takes me like 50 revolutions and one other thing...grease!!! I use a liberal amount of a molybdenum grease that really helps...gotta get it all back off with acetone and Q tips later, but worth it for the improved outcome.

I spin the bead tool around the tube, keeping the tube stationary.

I also use a tubing cutter, but you do need to remove a tiny bit after trim prior to beading...say .010-.015" from the end, due to the cutter creating a slight internal flare into the I.D. of the tube. I usually put a small countersink to the I.D. of the tube as well. It's easiest to do this in a lathe, but a hand file and hand countersink work just fine too.

I hope that helps.

S.
 
steveandmaysrocket said:
usually, what works best for me is to make very small incremental changes to the beading with the tube going around 2-3 revolutions for each minor depth adjustment...

Not sure if that makes sense? basically lots and lots and lots of spinning, as you very slowly increase the dept of the bead. usually takes me like 50 revolutions and one other thing...grease!!! I use a liberal amount of a molybdenum grease that really helps...gotta get it all back off with acetone and Q tips later, but worth it for the improved outcome.

I spin the bead tool around the tube, keeping the tube stationary.

I also use a tubing cutter, but you do need to remove a tiny bit after trim prior to beading...say .010-.015" from the end, due to the cutter creating a slight internal flare into the I.D. of the tube. I usually put a small countersink to the I.D. of the tube as well. It's easiest to do this in a lathe, but a hand file and hand countersink work just fine too.

I hope that helps.

S.
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Yes, it makes sense. I actually spend quite a bit of time preparing the end of the tube prior to flaring. It hasn't helped but I'm doing it anyway :) Maybe I just need to whack the tube off with a hacksaw and throw it in the flare tool with no prep. I haven't tried that yet!

This is what I do to prepare the tube prior to flaring:

"Before I flare, I cut the tube with a Ridgid tube cutter. When using the cutter I gently advance the knob after every couple of rotations to minimize deforming the wall of the tubing while cutting. I then use a very small round file to gently debur the inside of the tube. After that I use a small flat file to smooth the end of the tube. Finally, I use a purple Scotchbrite pad to debur."
 
I have the same tool. Technique is very similar except I make sure the end is square and flat. Then it goes into the clamp with a bucking bar used to make sure the end is flush to the block. Next the flare tool gets a light coat of Boelube. Snug everything and start turning. Once the cone makes contact, I start counting 1/2 turns. Each half turn I go backwards a half before rotating forward a full turn. After three full turns, I check the flare. Usually perfect but occasionally it needs a tiny bit more. After a few test flares, i know how many turns to use for a particular size tubing.
I tried it till the clutch released but it was too thin and too big in diameter.
Hope that helps.
 
bertschb said:
Yes, it makes sense. I actually spend quite a bit of time preparing the end of the tube prior to flaring. It hasn't helped but I'm doing it anyway :) Maybe I just need to whack the tube off with a hacksaw and throw it in the flare tool with no prep. I haven't tried that yet!

This is what I do to prepare the tube prior to flaring:

"Before I flare, I cut the tube with a Ridgid tube cutter. When using the cutter I gently advance the knob after every couple of rotations to minimize deforming the wall of the tubing while cutting. I then use a very small round file to gently debur the inside of the tube. After that I use a small flat file to smooth the end of the tube. Finally, I use a purple Scotchbrite pad to debur."
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I just realized you are flaring, not beading...

the flaring tool secret is back and forth, back and forth, back and forth...almost no pressure....back and forth...1/2 turn, 1/4 turn...Larry said Boeing lube, I use the Molybdenum, but my buddy swears by silver anti-sieze paste. One thing I do...it warm the end up with my heat gun a little...as in 20 seconds maybe...and if I have a kid handy...(or my wife isn't mad at me that night...((it could happen...)) I'll keep a little heat gun heat on through the flaring operation.

it's a pain in the butt.

Good Luck. (back and forth) takes ten minutes to do a really good, non-leaky one...


S
 
I have the rigid tool, same issue, I’m actually sending it off for warranty repair. I bought a rolo from spruce to compare. I haven’t done any on it yet, but the rigid over flared every time. The clutch is too tight in my opinion.
 
wirejock said:
I tried it till the clutch released but it was too thin and too big in diameter.
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Thanks Larry. The instructions say to insert the tube flush for "normal" flares. If you want a wider flare, you insert the tube a little further so it sticks out a bit. If you want a smaller flare, you insert the tube so it isn't quite flush. I've tried multiple variations and it does affect the width of the flare. But, ALL of them look like the picture in my first post (one side is taller than the other).
 
Thanks for all the feedback guys! These fuel tanks SUCK!!! I've been totally paranoid about leaks the entire time I've been working on them. The fuel vent line seemed pretty straightforward until I started seeing these lousy flares and then reading about leaking fuel vent lines here on the forum. I'm trying so hard to do these tanks right but every step of the way is a challenge. Absolutely hate fuel tanks.

I hate throwing $150 down the drain for the Ridgid 377 but I just ordered the Rolo-Flair. I can NOT afford any leaks anywhere in these fuel tanks or I'm going to throw in the towel.
 
bertschb said:
Actually, it kind of is. Many reports here of leaking fuel vent lines that required removing the tanks to repair :-(
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If you have gotten as far as tanks, you will be fine. Late advice, is possibly better than none....but be EXCEEDINGLY clean...I used a slightly different product than the Pro Seal and it proved to serve well for 20 years of pretty solid aerobatics without a leak. You'll be fine if you stick to the game plan, coat EVERYTHING... and one small thing no-one seems to mention, but we do every day while fay sealing...wet the tip of your finger with isopropyl alcohol and LIGHTLY go over every seam that you can. The alcohol helps the Pro Seal cure...and you can get the material to lay in a bit better and flatter with this technique. Another pit fall to avoid, is more work...but let the PRC nearly cure, around bucked shop heads of rivets before you clean it off....this is way harder and usually ends up needing MEK here and there to final clean....but you get better sealing in the rivets this way.

I've done 9 sets of tanks in the last 30 years....you will be fine.

The Rolo Flaring tool is SO superior...worth its weight in gold...


Steve.
 
Lots of good info above...I have the Rolo flair so I'm not familiar with the Ridgid your using but looking at the picture here are a few thoughts.

1-Is the tubing square after cutting...I use a small machinist square to confirm after I have deburred and polished with a scotch brite
2-Are you using the locking bolt located on the side of the main body (silver). If so is it shifting the centerline of the tooling off to one side. looking at the part drawing again it looks like its necessary to lock the side bolt to clamp the tubing.
3-When you start a flare are you able to determine if the tooling cone is centered or is it contacting one side before the other.

Is the tall side of the flare always created from the sam position? For example is it from the side of the tool that has the clamping bolt? If it is you could use a shim on one side between the main body and the clamping bars of the tool to determine if you get different results.

Don't give up!
 
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