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Having trouble flaring fuel vent line

bertschb

bertschb

Where's my engine????
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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?

IMG_0345.jpg


IMG_0340.jpg
 
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JonJay said:
That’s weird.
Is the die square to the tool?
Click to expand...
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?
Click to expand...
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).
Click to expand...

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.
Click to expand...

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.
Click to expand...
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.
Click to expand...
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."
Click to expand...
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).
 
Ps I also just bought and received the aircraft specialty kits, as I don’t trust my flaring and bending enough.
 
lipper03 said:
Ps I also just bought and received the aircraft specialty kits, as I don’t trust my flaring and bending enough.
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Oh, I got all the Aircraft Specialty stuff I could buy. But, they don't do fuel vent lines (I asked).
 
Beg, borrow, lie, cheat, or steal the Rolo flaring tool...about $150 from Spruce.
Your problems will be solved.

Those Rigids are a pain in the butt.
 
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!
 
bertschb said:
That's a great idea. The end of the tube looks square but I'll try that tomorrow.
Click to expand...
I square the end of the tube by inserting it through the tool's bar in reverse, then cutting with a fine hacksaw along the bar surface. It's hardened, so you won't damage it. Finish off with a fine file or emery, then debur inside and out before reversing the tube in the bar and doing the flare.
 
Thierry A said:
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!
Click to expand...
1- Yes, it's square (and carefully deburred and polished)
2- Yes, I'm using the locking bolt. It does shift the centerline of the tooling but it's designed to work that way.
gap.jpg
3- Cone is centered
cone.jpg
I haven't checked to see if the tall side of the flare is always on the same side. I've given up on the tool after 8 tries and ordered the Rolo-Flair instead.
 
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PhatRV said:
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
Click to expand...
Aren't AN fittings a 37 degree flare as opposed to a 45 degree automotive flare? Does the 45 degree deburring tool upset the 37 degree flare?
 
jliltd said:
Aren't AN fittings a 37 degree flare as opposed to a 45 degree automotive flare? Does the 45 degree deburring tool upset the 37 degree flare?
Click to expand...
No problem after 80 hours of test flying. The tubing is soft aluminum and it will conform to the AN surface.

If you have a flying airplane and you find leaks: use this type of AN seal so you don't have to redo the fitting,
www.aircraftspruce.com

Del Fitting Seals Aluminum | Aircraft Spruce ®

Del Fitting Seals Aluminum DEL fitting seals are designed to eliminate leakage due to scratches on the sealing surface, improper torquing, or poor finishes on tube ends, in high or low pressure applications. For use with ...
www.aircraftspruce.com www.aircraftspruce.com
 
My good friend and hangar mate used a 45 degree automotive flaring tool on his RV-8 project. He had a mentor who said it wouldn't make any difference since the aluminum was soft and conformal. After 3 years of trouble with his brake lines leaking he change out for new tubing with 37 degree flaring tool. No more leaks. This was on gun-barrel drilled Grove gear, so he was able to work on the ends rather than having a long tube to replace.
 
I'll open myself up to ridicule. Here's some things you probably already know.

The flaring cone is not concentric. Only a small portion of it contacts the workpiece as it turns.
The "clutch" is actually a spring that disengages the handle as a function of spring force/displacement.
The tool is designed to flare a variety of tubing thicknesses and materials.

IMO, the associated spring force for thin wall 3003 is too great. First few flares I tested were paper thin and the flare ODs were not even because the metal wasn't just be formed, it was being deformed -> uneven and very thin flare material thickness. In engineering terms, it was getting the s#!t squished out of it.

The flare shape is basically complete when the spring starts to displace the handle. I do 1/2 turns or so after said point for a total of 11/2 - 2 turns. Makes for a nice, even, burnished, relatively un-thinned (stronger) flare.

On another note, having mismatched flare angles between male/female faying surfaces is an accident waiting to happen. May pass a leak test but what was a distributed load (2D) is now more of a point load. Without said distribution, future crack development potential has risen exponentially. Additionally, if the joint/torque is used to make the parts conform, you've just cold worked the material at it's point of highest stress. Successful time at condition isn't relevant unless it is tested beyond the expected life of the system (aircraft). It's good until it (suddenly) isn't.

Build safe. Fly safe.
 
Everyone is focused on their favorite tool. Ridgid makes good tools. 2 things might be causing this.

The OP mentioned the tubing had been bent then straightened. That changes the wall thickness a tiny bit around the circumference. So the flaring tool is trying to flare different thicknesses.

Second, that tool is made for copper so the "clutch" is probably too tight. Try stopping before the clutch slips.
 
Freemasm said:
I'll open myself up to ridicule. Here's some things you probably already know.

The flaring cone is not concentric. Only a small portion of it contacts the workpiece as it turns.
The "clutch" is actually a spring that disengages the handle as a function of spring force/displacement.
The tool is designed to flare a variety of tubing thicknesses and materials.

IMO, the associated spring force for thin wall 3003 is too great. First few flares I tested were paper thin and the flare ODs were not even because the metal wasn't just be formed, it was being deformed -> uneven and very thin flare material thickness. In engineering terms, it was getting the s#!t squished out of it.

The flare shape is basically complete when the spring starts to displace the handle. I do 1/2 turns or so after said point for a total of 11/2 - 2 turns. Makes for a nice, even, burnished, relatively un-thinned (stronger) flare.

On another note, having mismatched flare angles between male/female faying surfaces is an accident waiting to happen. May pass a leak test but what was a distributed load (2D) is now more of a point load. Without said distribution, future crack development potential has risen exponentially. Additionally, if the joint/torque is used to make the parts conform, you've just cold worked the material at it's point of highest stress. Successful time at condition isn't relevant unless it is tested beyond the expected life of the system (aircraft). It's good until it (suddenly) isn't.

Build safe. Fly safe.
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great point you added....if the OD of your tube is ragged looking after flaring, the flare will break, just a matter of when. looking at a lot of flares over the years, many tend to be over flared, which stretches the bejeezus out of the tubing, work hardening to the point where a little vibration over time, will crack and you don't really find it till you smell fuel in the cabin.

I've gone away from aluminum tubing for vent lines into the cabin area, switching to hose and securing with adel's.

If this is the in-tank vent line, you're stuck with aluminum.

Steve
 
steveandmaysrocket said:
great point you added....if the OD of your tube is ragged looking after flaring, the flare will break, just a matter of when. looking at a lot of flares over the years, many tend to be over flared, which stretches the bejeezus out of the tubing, work hardening to the point where a little vibration over time, will crack and you don't really find it till you smell fuel in the cabin.

I've gone away from aluminum tubing for vent lines into the cabin area, switching to hose and securing with adel's.

If this is the in-tank vent line, you're stuck with aluminum.

Steve
Click to expand...
Yep, and that is the reason I went with a hydraulic double flare tool. More expensive but I have confidence in the flares and their longevity…also pretty hard to make a bad flare, and if you do it is pretty obvious.
 
rocketman1988 said:
Yep, and that is the reason I went with a hydraulic double flare tool. More expensive but I have confidence in the flares and their longevity…also pretty hard to make a bad flare, and if you do it is pretty obvious.
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I agree...definitely a better methodology.
 
jliltd said:
My good friend and hangar mate used a 45 degree automotive flaring tool on his RV-8 project. He had a mentor who said it wouldn't make any difference since the aluminum was soft and conformal. After 3 years of trouble with his brake lines leaking he change out for new tubing with 37 degree flaring tool. No more leaks. This was on gun-barrel drilled Grove gear, so he was able to work on the ends rather than having a long tube to replace.
Click to expand...
Ya gotta wonder...
 
Update:
I made four more flares to see if the longer side of the flare (see photo in post #1) is always at the same location in the tool even when changing the orientation of the tubing when inserting it into the tool. And it is (see photo below). Yes, it's a small sample size but 4 for 4 makes me think it's not a coincidence. I also experimented with tightening then backing off then tightening over and over as suggested and that didn't change the outcome. Neither did stopping the flare before the clutch engages. All 12 of the flares look like the picture in the first post.

flare.jpg
 
Freemasm said:
The flaring cone is not concentric. Only a small portion of it contacts the workpiece as it turns.
Click to expand...
This makes me wonder if the same side of the cone hits the same side of the tube flare with each rotation. IOW, if the "wider" sweep of the cone always hits the same area of the flare towards the end of the flaring operation, it seems this might disproportionately squeeze that side of the flare to the point where it's taller (and thinner) than the opposite side of the flare.

I don't know if that makes any sense but the die itself doesn't look malformed to this untrained eye.
 
bertschb said:
This makes me wonder if the same side of the cone hits the same side of the tube flare with each rotation. IOW, if the "wider" sweep of the cone always hits the same area of the flare towards the end of the flaring operation, it seems this might disproportionately squeeze that side of the flare to the point where it's taller (and thinner) than the opposite side of the flare.

I don't know if that makes any sense but the die itself doesn't look malformed to this untrained eye.
Click to expand...
Maybe try to rotate the tube as you form the flare?
 
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