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Fuel Line Flaring

When I’m flaring the ends of my fuel lines, I’m ending up with rough jagged edges…. Like chatter marks. Is this something that can be lightly sanded smooth, or is it a prep/technique problem? I’m standing the ends square, deburring inside and out, and using some oil on my rolo-flair. Anything I’m missing?
 
First attempt at attaching a photo. Let’s see if it works.
 

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What kind of flaring tool are you using? The cheap ones I have used have left streaks like that. I upgraded to a Ridgid tool with an off-center forming cone that rolls along the flare rather than the fixed kind that smear the metal.

Edit: If you're using a rolo-flair, I think they're supposed to rotate and create a smooth surface. It looks like yours may be stuck and smearing the metal? There shouldn't be those circular grooves on the flare face.
 
Grease!

Looks like the male die is rough or worn. Maybe it could be smoothed up a bit? Also, a little grease might help.
 
bad tool bad results

Wow I don't know who made the tool But it needs major repair or junking.
I've flared hundreds, maybe thousands of flares and with the cheapest tool I got better flares than that.
Me thinks you need another tool
Art
 
should be

In my opinion, the flare part that rests on the AN fitting should be smooth and shinny. This shown is not acceptable and probably wont seal. The outer edge sometimes has a rough appearance like in the picture. sometimes I will sand down the outer edge to prevent the flare from cracking in severe environments. JMHO
 
It’s a brand new tool. I cleaned up the cone and it produced this flare.
 

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Junk

It’s a brand new tool. I cleaned up the cone and it produced this flare.

The tool is junk. Borrow someone else's and try again.Here is a picture from google. Also, your flare may have the wrong angle. Aircraft is 37 degrees, and automotive and AC are 45 degrees. they are not compatible.
 

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Here is the result when I don’t use the back and forth method, and just turn it all the way once, then back out…. Much less scoring
 

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better

Here is the result when I don’t use the back and forth method, and just turn it all the way once, then back out…. Much less scoring

This looks better, but hard to see the details in the photo. the angle still looks wrong, but that could be an optical delusion.

EDIT: After closure look at photo, this still looks unacceptable to me. But it is hard to tell from photo. maybe a nearby tech counselor can have a look at it.
 
TJ---there is debris on the flaring cone and inside the tube. If the cone is removable from the tool, clean it to get the embedded aluminum off the cone, You can use some very fine sand paper, crocus cloth, or even a wire wheel on a grinder to clean it up. Check the inside of the end of the tube for cutting debris----yes even if you use a tubing cutter---.
The scratched on the flare show me that there is embeded debris on probably both the flare cone, and the end of the tube ID. As you go through the flaring process, if there is any debris, the cone is pressing it INTO the tube as it expands to make the flare. So as the cone turns, is dragging little pieces of debris around.

Always debur the ID of the tube, and square the end with a fine file. ( I put mine in the lathe and turn the end square and smooth. In the production shop, we have a squaring machine that does this). With a clean tube, and flaring cone, the finished product will look like the pic Jim posted.

Also----it looks like the tube is over flared---maybe my eyes. Retract the tube slightly (.035-.060) and see how it looks. The maximum OD of the flare should be no larger than the OD of the sleeve, and minimum OD would be no smaller than the sleeve margin. Ideally, the OD of the flare would be somewhere in the middle.

This is not hard, but it does take some practice to get right. Different flare tools require a slightly different tube extension before flaring. I have 3 different tools and they are all different. Same with the wall thickness of the tubes. Know what you're working with, look at known good examples, and with alittle practice you can make very acceptable flares. We we hear of builders having leak issues on rigid tubes, we go over these same things.

Tom
 
After thoroughly cleaning both the tool and the material, deburring, using either grease or oil, I still can’t produce a flare any better than I already have. Guess I’ll try another tool.
 
Since you’ figured out the photo posting, how about a picture of the flaring tool. The lines on the aluminum tube looks like it might be machining marks left on the flaring mandrel where the manufacturer didn’t put a good polished finish on it.
 
TJ---there is debris on the flaring cone and inside the tube. If the cone is removable from the tool, clean it to get the embedded aluminum off the cone, You can use some very fine sand paper, crocus cloth, or even a wire wheel on a grinder to clean it up. Check the inside of the end of the tube for cutting debris----yes even if you use a tubing cutter---.
The scratched on the flare show me that there is embeded debris on probably both the flare cone, and the end of the tube ID. As you go through the flaring process, if there is any debris, the cone is pressing it INTO the tube as it expands to make the flare. So as the cone turns, is dragging little pieces of debris around.

Always debur the ID of the tube, and square the end with a fine file. ( I put mine in the lathe and turn the end square and smooth. In the production shop, we have a squaring machine that does this). With a clean tube, and flaring cone, the finished product will look like the pic Jim posted.

Also----it looks like the tube is over flared---maybe my eyes. Retract the tube slightly (.035-.060) and see how it looks. The maximum OD of the flare should be no larger than the OD of the sleeve, and minimum OD would be no smaller than the sleeve margin. Ideally, the OD of the flare would be somewhere in the middle.

This is not hard, but it does take some practice to get right. Different flare tools require a slightly different tube extension before flaring. I have 3 different tools and they are all different. Same with the wall thickness of the tubes. Know what you're working with, look at known good examples, and with alittle practice you can make very acceptable flares. We we hear of builders having leak issues on rigid tubes, we go over these same things.

Tom
Agree with Tom looks like over flared. No need to run the tooling to a very tight point, just in enough to form the flare. Experiment you'll get it
 
Use a saw blade or abrasive cut off wheel to cut the tube and stop using, what I assume is a wheel type tubing cutter. I was getting the same rough edges using the same flaring tool. The tube was getting work hardened by the tubing cutter. It was even worse when I had to do some stainless. Switched to an abrasive disc and everything got much better.
 
You can use an abrasive wheel to cut the tube with no issues. You can still use a file file to finish the ends. In the 'old days', we had a flaring bar and would insert the tube so it was on the flat side, not the flared side. Pretty easy to square things and make a smooth end. Today in our prototype and production shops, we have a more modern approach with a saw, a ID/OD deburing machine. Thats after the tube has been cut to length, and squared.

In your case, the raised peaks on the flaring cone, that make is a rolled flare, appear to have some inbedded material on/in it. The flare rollers we have are stainless, ao its pretty easy to keep them clean. I have a Parker Roloflare, but really dont use it much. My Rigid RFT37 has been my go to flaring tool for years, and even though I have the big machine, I still use the small flare bar for quick and easy non production mockup stuff------and its portable.

The Vans kits are designed so generally available tools can be used to build these plans without expensive flaring tools, 3 axis CNC benders and other things. But while a hand flaring tools is perfectly fine, you have to learn to work with it to produce acceptable, and reliable results. Get some scrap tube and play with it. See what a great flare looks like, and then try and mimic it.
With the different wall thicknesses and materials we use, I have made some gauges to have the right amount of tube extension from the flare dies, so the OD of the flare is witing specs. On the Vans kits, you mostly be flaring 3/8, .035 wall 3003 tubing. Its fairly soft, and if you over flare it you can 'thin' the flare wall and have it develop a crack. Thats because you are compressing the tube between the flare cone, and the flare bar, and the tube will give.

Practice on some scrap. If you arent sure, have a local A&P, IA, EAA tech counselor, or knowledgeable other builder to look at it. It makes for a really bad day to assume the flares are good, do a test run after everything is installed, just to find unacceptable and leaking tubes. If you arent sure, stop and seek help!

Tom
 

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I think you are really over flaring it. Read the manual that came with the roloflair, you tighten the flare handle untill you feel slight resistance. You don't crank it down tight. As other mentioned, check the cone and make sure it is not rough or has aluminum stuck to it. You can remove it by punching out the roll pin, then clean up the cone with scotchbrite or a polish wheel.
 
check your angle?

Kind of like the guys before said, check your tool angle. It looks way more like a 45 from that angle than a 37.
Also make sure your tube end if filed and/or Scotchbrite wheeled very smooth before the flare process or you will get those "cracks".
Just my 2 C. Good luck.
 
The tool is brand new. Parker 37 degree, confirmed. I’ve cleaned the cone each time before flaring, and deburred inside and out. I’ve tried both grease and cutting fluid. I’ve cleaned up the cone with some very fine sandpaper to ensure nothing is embedded.
 
Warren posted a very good video. There have been hundreds if not thousands of RV's built with Rolo-Flair tools including mine. It is a quality tool. Pay special attention to the video around the 5:30 mark and make sure you are bumping the tubing up to that arm and not pushing it past it. If you do it will over flair the tubing. I suspect that is your issue. As the gentleman in the video says, do not crank down too hard on the tee handle. Inspect the flair with a magnifying glass for cracks and roughness. There have been aircraft lost due to poorly formed flairs. If you still have trouble, get a builder with experience in the operation of this particular tool to come show you how it should be operated.

My two cents.

Thanks,

Joe
 
Backside

Although we have all been talking about the sealing surface on the flare side, the back side is important too.
The backside is where the B-nut and sleeve make contact with the tubing. Some poor quality tools leave 2 ridges here from the dies. This is no good. The backside doesn't need to be perfect, but must allow the B-nut and sleeve to push on the flare most of the way around in order to get a good seal; especially on soft tubing. JMHO
 
Did a little more polishing on the cone, switched to a little bit heavier oil, played with it a little more, and produced this flare. Better than the others I think. The video was good but he wasn’t doing anything more or less than what I’m doing.
 

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Also be sure to square off your tubing and debur and clean up the end after you cut it, but before you flare. You are stretching the tubing, and any sharp edges could be a place to start a crack..
 
Details matter . . .

Did a little more polishing on the cone, switched to a little bit heavier oil, played with it a little more, and produced this flare. Better than the others I think. The video was good but he wasn’t doing anything more or less than what I’m doing.

Good job! I have some picts from 2015 going through a similar experiment and your last one looks excellent. Are you using 3003 tubing? As mentioned don't over flare it will thin the flared section edge and fail where the B nut contacts it, but this is a different thread.
 
My A&P instructor shared some really good tips. Take a small 1" square block of wood and with a drill press, put a 3/8" hole in the center. You can then slide in the end of the 3/8" tubing you are going to want to flare. Use the block holding the tubing to then sand the end of the tubing perfectly square and smooth. Just stick in the tubing, then rub the block and tubing over a smooth surface with sandpaper. This gets it perfectly squared off and the end nice and smooth. You can use a dime as a gauge for how much of the tubing end to leave above the surface of the flaring tool. Use oil and don't over flare the tubing. Screw it down until it is firm, but not tight.
 
I’ve been able to get some consistently good flares. A smoother cone and liberal amounts of oil have seemed to do the trick. Thanks everyone for the help. Takes a village to build a plane!
 
I’ve been able to get some consistently good flares. A smoother cone and liberal amounts of oil have seemed to do the trick. Thanks everyone for the help. Takes a village to build a plane!

Glad you solved it. I had exactly the same experience - one or two drops of oil on the cone, where it will contact the tube, is all it takes. There should not be a need to back up until the flare is complete.
 
I always burnish the flare with scotch brite after I am done, and clean up the edges as required with the scotch brite. Haven’t had a leak yet.
 
I test aircraft hydraulic system components for a living so I'm working with flared fittings operating from 3,000 psi to over 20,000 psi. The outside edge cracking is because one reason, the tubing is overflared for the finish the end had prior to flaring. The only time I see a piece of tubing overflared is if the nut no longer fits over it.

What I mean by the statement above is, if the end of the cut tubing is rough or damaged, after a point in the flaring the edges will start to crack. If these cracks aren't deep, you can run the edge on a grinder of belt sander to remove, but, it is usually better to cut it and reflare.

When I cut tubing for a flare, I sand or polish the end and deburr the ID. Make sure your flaring tool is properly lubed and there is no debris to mess up the surface finish.

In the end, you can use the copper seals for JIC fittings. I've found they work very well to seal damaged fitting ends or bad flares.
 
I had the occasion the other day to make some custom tubes, and thought I'd share this. I took a pic of this out of a NAVAIR textbook---no offense to our Air Force brothers, but its the book I have. The pic shows the min/max MIL SPEC of the flare as compared to the sleeve.
I guess I could grab some sleeves and give you the min, max, and average OD of the flares, but when using a hand flaring tool, even a .020 length change in where the tube is located in the flare bar/die, can make a difference.

Even different grades of tubing as well as well thicknesses all are variables to factor in. I can tell you that hand flaring .375x.065 wall 304 stainless is tough. But, fortunately, most of you will be flaring 3003O-.035 wall which is pretty soft.

Hope that helps.

Tom
 
There i was

I had the occasion the other day to make some custom tubes, and thought I'd share this. I took a pic of this out of a NAVAIR textbook---no offense to our Air Force brothers, but its the book I have. The pic shows the min/max MIL SPEC of the flare as compared to the sleeve.
I guess I could grab some sleeves and give you the min, max, and average OD of the flares, but when using a hand flaring tool, even a .020 length change in where the tube is located in the flare bar/die, can make a difference.

Even different grades of tubing as well as well thicknesses all are variables to factor in. I can tell you that hand flaring .375x.065 wall 304 stainless is tough. But, fortunately, most of you will be flaring 3003O-.035 wall which is pretty soft.

Hope that helps.

Tom
When building rocket test cells in my youth, I did lots of hand flaring of stainless. It is not hard, but one must have very good quality tools and change them often. And must never forget the b-nut and sleeve. This was yoga class before there was yoga classes.
 
Only downside of this tool is I don't it will fit in the plane when you have to so a flare inside the plane. This is where the line goes into the connector block which has the by pass to the return line (just under the throttle).
 
Robert----planning ahead will solve that problem for you. Flare one side, then pull the line out so you can get to the other end. OR----wait to rivet the floor panel until all that plunbing was finished.
Bulkhead fittings would have been great, but there isnt enought edge distance to make the hole and have everything align---as I recall.

Tom
 
If you’ve already installed your floor panel, removing the handle from the tool allows it to fit ok too - tight, but it works.
 
The tool is junk. Borrow someone else's and try again.Here is a picture from google. Also, your flare may have the wrong angle. Aircraft is 37 degrees, and automotive and AC are 45 degrees. they are not compatible.

SO.... What is currently considered the best flaring tool for a 12iS build?
 
What textbook?

I took a pic of this out of a NAVAIR textbook... shows the min/max MIL SPEC of the flare as compared to the sleeve.

Tom: if you don't mind... what's the NAVAIR text?

Always looking for good references to keep handy.

thanks,
 
Ron--I got these from a Marine helicopter technicaian. One was from Aviation Maintenance Publishers, # EA-AH-1. The other is from IAP ( might be the same publishers), # EA-ITP-GB. That one is a general textbook, the first one is on Hydralic systems.

Certainly there have been updates and many revisons that are more current than I have, but very good information in both.

I would think that the A&P/IA course textbooks would be good to.

Tom
 
Brown tool

SO.... What is currently considered the best flaring tool for a 12iS build?
For the soft aluminum tubing we have in the kits any good quality tool from Brown's Tool, Avery or Cleveland should be adequate.

The stainless is a different animal, and double flares even more so, but we do not use those sophisticated types on our planes.
 
not really

"...The stainless is a different animal, and double flares even more so..."

Speaking in reference to the double flare part of your statement, I used a hydraulic double flare tool for every flare in my -10. It has a learning curve but no more so than trying to use a single flare unit and not crack the flare.

Once you understand how the double flare tool works, the flares that it produces are consistent, repeatable, and do not leak...and you really don't worry about the flare cracking...

The downside? The tool acquisition cost...
 
Ron--I got these from a Marine helicopter technician. One was from Aviation Maintenance Publishers, # EA-AH-1. The other is from IAP ( might be the same publishers), # EA-ITP-GB. That one is a general textbook, the first one is on Hydraulic systems...
Tom

Tom: Thank you.

Would have replied sooner... had to knock out some chores
 
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